Apparatuses, methods and systems for intravascular ultrasound circumferential solid-state array dynamic beamforming and methods of use

Abstract

An intravascular ultrasound (IVUS) system having an IVUS catheter, an IVUS console, and a patient interface module are disclosed. A representative IVUS console is configured to generate commands and activation signals according to predetermined activation patterns. A representative IVUS catheter includes an elongated housing; a plurality of ultrasonic transducer elements arranged distally in a circumferential array; and a plurality of ultrasonic transducer controllers, with each ultrasonic transducer controller coupled to a corresponding subset of ultrasonic transducer elements, and each ultrasonic transducer controller configured, in response to one or more commands, to activate one or more ultrasonic transducer elements within a selected sub-aperture of the circumferential array to generate a focused ultrasonic beam, typically having a selected focal point and a selected scan line. In a representative embodiment, each ultrasonic transducer controller is further configured to store one or more portions of the predetermined activation patterns.

Description

APPARATUSES, METHODS AND SYSTEMS FOR INTRAVASCULAR ULTRASOUND CIRCUMFERENTIAL SOLID-STATE ARRAY DYNAMIC BEAMFORMING AND METHODS OF USECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a nonprovisional of and claims priority to and the benefit ofUnited States Provisional Patent Application No. 63 / 602,532, filed November 24, 2023, inventors Randall D. Hamlin et al., titled “Apparatus, Method and System for Intravascular Ultrasound Circumferential Solid-State Array Dynamic Beamforming”, and is a nonprovisional of and claims priority to and the benefit of United States Provisional Patent Application No. 63 / 668,044, filed July 5, 2024, inventors Randall D. Hamlin et al., titled “Apparatuses, Methods and Systems for Intravascular Ultrasound Circumferential Solid-State Array Dynamic Beamforming and Methods of Use”, which are commonly assigned herewith, incorporated herein by reference with the same full force and effect as if set forth in their entireties herein, and with priority claimed for all commonly disclosed subject matter.FIELD OF THE INVENTION

[0002] The present invention, in general, relates to intravascular ultrasound imaging, and more particularly, relates to apparatuses, methods and systems for intravascular ultrasound circumferential solid-state array dynamic beamforming and methods of using the apparatuses and systems in human or veterinary subjects.BACKGROUND OF THE INVENTION

[0003] Intravascular ultrasound (“IVUS”) imaging is widely used in interventional cardiology as a diagnostic tool for a diseased vessel within the human body, such as an artery, to determine the need for treatment, to guide the intervention, and / or to assess its effectiveness. These imaging catheters are used within the vascular system to transmit sound waves with the purpose of creating two-dimensional (2D) images from inside the vasculature. An IVUS catheter, which includes one or more ultrasonic transducers (also referred to equivalently herein as ultrasound transducers) which emit and receive ultrasonic energy, is inserted into the vessel of interest and guided to the region to be imaged. The ultrasonic waves are reflected, to varying degrees and at varying depths, by discontinuities in the tissue structure and density, blood cells, and other anatomical and physiological features. The reflected ultrasonic waves are, in turn, received by one or more of the ultrasonic transducers and converted into electrical signals which, in turn, are provided to an IVUS imaging system. The IVUS imaging system processesthe received signals to produce an image, such as a cross-sectional image of the vasculature in the region where the IVUS has been placed. These images are then used to determine the vessel anatomy, the existence or extent of disease such as clot or other obstruction formation, and to measure the dimensions of the vessel area and degree of stenosis, for example and without limitation.

[0004] Two different technical architectures have been implemented to generate intravascular ultrasound images. Both techniques create a 360-degree circumferential ultrasound image, but each has unique shortcomings. All of the current IVUS catheters solely provide a fixed geometric beam focus, based on their physical properties, that cannot be varied. In addition, none of the current IVUS catheters has the ability to dynamically focus the ultrasound beam.

[0005] For example, one architecture includes a mechanical, 360-degree rotational single ultrasonic transducer element or a multiple ultrasonic transducer element unit. The mechanical rotation of a single large element or group of elements relies solely on a fixed geometric focus to determine the focal zone of highest resolution, and cannot be dynamically changed.

[0006] Another architecture includes a solid-state array made up of multiple ultrasonic transducer (e.g., piezoelectric zirconate transducer (“PZT”)) elements arranged in a circumferential manner. These previous solid-state circumferential array architectures transmit ultrasound energy either using only one ultrasonic transducer element at a time or using only one collective group of ultrasonic transducer element at a time. The beam pattern (focus) transmitted by this single-element or single group of elements, like the rotational devices, is dictated by the mechanical geometry of the elements and cannot be dynamically controlled. The insonification beam pattern of a single small element is diffuse and has little focus. This results in comparatively low imaging resolution, with no capability to produce a higher resolution focal zone. This transmission by a single ultrasonic transducer element or single collective group of ultrasonic transducer elements also leads to comparatively weak insonification and a comparatively low signal-to-noise ratio, which in turn limits both resolution and penetration depth. This is illustrated in FIG. 1, which shows the radiated beam pattern for a single ultrasonic transducer element, illustrating that the ultrasonic energy is diffuse and comparatively poorly focused.

[0007] Additional difficulties associated with the current IVUS catheters pertains to their form factors and lack of flexibility. In some instances, the configurations, arrangements, and sizes of the electronics within the current IVUS catheters requires both an increased diameter of the catheter and further interferes with the flexibility of the catheters, inhibitingtheir use in comparatively smaller vasculatures or other comparatively narrow or smaller locations, and further preventing insertion of the catheter in comparatively twisting or bending locations.

[0008] Accordingly, a need remains for an IVUS catheter apparatus, method, and system which provides dynamic and user-selectable and / or user-programmable focusing of the ultrasonic beam. Such an IVUS catheter apparatus, method, and system should provide for lateral control of the transmitted ultrasonic energy and control of the intensity of the sonification pattern. Such an IVUS catheter apparatus also should have a comparatively small form factor with a comparatively reduced diameter, and sufficient flexibility for access to desired locations with the vasculature, such as insertion into and around sharp bends in vessels, among other features.SUMMARY OF THE INVENTION

[0009] The exemplary or representative embodiments of the present invention provide numerous advantages. Various representative embodiments provide an IVUS catheter apparatus (or more simply, an IVUS catheter), method and system for solid state intravascular ultrasound catheterization that enables not only use of modem ultrasound imaging techniques, but also enables high spatial and temporal resolution imaging with greater dynamic range and more flexible imaging modes. Representative embodiments provide dynamic and user- selectable (and / or user-programmable) focusing of the ultrasonic beam, including lateral control of the transmitted ultrasonic energy and control of the intensity of the sonification pattern, and also including user selection of the penetration depth (also referred to as the field of view, e.g. 2 cm, 3 cm, or 4 cm, for example and without limitation) and other user-selectable parameters, such as overall gain (e.g., overall image brightness), for example and without limitation. The representative embodiments of an IVUS catheter also have a comparatively small form factor with a comparatively reduced diameter, and further have sufficient flexibility for access to desired locations with the vasculature, such as insertion into and around sharp bends in vessels, among other features.

[0010] The representative embodiments further provide arbitrary transmit focusing, using selectable, active sub-apertures and selectable delay profiles. The representative embodiments include the capability to use multiple transmit foci to create a single composite scanline with a greater focus depth of field. In addition, real time receive sub-apertures provide for individual scanlines in a single transmit / receive event. This increases imaging frame rate compared to current synthetic aperture techniques and improves the signal-to-noise ratio (SNR) and improves the dynamic range for greater image penetration depth.

[0011] The representative embodiments further provide arbitrary scanline positioning, which further enables creating high density scanlines for improved lateral resolution and far- field resolution. This also serves to reduce the geometric impact of beam spreading in a very tightly-curved array. The representative embodiments further provide an IVUS system that enables both traditional geometric delay beamforming as well as synthetic reconstruction. The representative embodiments further provide the capability to electronically steer the ultrasonic transmit and receive sequence, to enable imaging modes such as phased array imaging or spatial compounding, for example and without limitation.

[0012] It should be noted that, as utilized herein, unless indicated to the contrary or as required by the context, the terms “ultrasonic” and “ultrasound” are generally utilized interchangeably and equivalently herein, and no limitation is intended or should be inferred from usage of “ultrasonic” rather than “ultrasound” and vice-versa. For example and without limitation, any reference to an ultrasonic transducer or ultrasonic transducer element should be understood to mean and include an ultrasound transducer or ultrasound transducer element, and vice-versa. Also for example and without limitation, any reference to an ultrasonic transducer controller should be understood to mean and include an ultrasound transducer controller, and vice-versa. Also for example and without limitation, any reference to an ultrasonic beam or wave should be understood to mean and include an ultrasound beam or wave, and vice-versa.

[0013] In a representative embodiment, an intravascular ultrasound catheter apparatus, may comprise: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart within the elongated housing, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

[0014] For such a representative embodiment, the plurality of ultrasonic transducer controllers may be distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements. In another representative embodiment, the plurality of ultrasonic transducer controllers may be distributed and spaced apart circumferentially within the elongated housing and arrangedspaced apart longitudinally from the circumferential array of the plurality of ultrasonic transducer elements.

[0015] In a representative embodiment, an intravascular ultrasound (IVUS) catheter apparatus may comprise: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

[0016] In a representative embodiment, an IVUS catheter may further comprise: a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with a catheter guidewire. In a representative embodiment, an IVUS catheter may further comprise: a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance.

[0017] In a representative IVUS catheter embodiment, the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate the focused ultrasonic beam having a user-selectable (and / or user-programmable) focal point, focal distance or focal length and a user-selectable or user-programmable scan line center. In a representative IVUS catheter embodiment, other imaging parameters are also user-selectable and / or user- programmable, such as user selection of the penetration depth (also referred to as the field of view) and other user-selectable parameters, such as overall gain (e.g., overall image brightness), for example and without limitation

[0018] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selectedsub-aperture of a plurality of sub-apertures of the ultrasonic transducer assembly. In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of subapertures of the ultrasonic transducer assembly, wherein each sub-aperture, of the plurality of sub-apertures, comprises a predetermined number of serially or sequentially adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements. In a representative IVUS catheter embodiment, for example and without limitation, each sub-aperture, of the plurality of sub-apertures, is offset from an adjacent sub-aperture, of the plurality of sub-apertures, by one ultrasonic transducer element of the plurality of ultrasonic transducer elements. In another representative IVUS catheter embodiment, also for example and without limitation, the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the selected sub-aperture, followed by activating one or more ultrasonic transducer elements of a next adjacent sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, to successively generate a series of focused ultrasonic beams around the entire circumferential array of the plurality of ultrasonic transducer elements.

[0019] In a representative IVUS catheter embodiment, each sub-aperture, of the plurality of sub-apertures, comprises a predetermined number of adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements. In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected subaperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0020] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns. In a representative IVUS catheter embodiment, each predetermined activation pattern, of the plurality of predetermined activation patterns, comprises: a selection of ultrasonic transducer elements for activation, from the corresponding subset of ultrasonic transducer elements. In a representative IVUS catheter embodiment, for example and without limitation, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprisesone or more memory circuits or registers, and wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to store the plurality of predetermined activation patterns in the one or more memory circuits or registers.

[0021] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, by switching an activation signal or voltage to the one or more ultrasonic transducer elements.

[0022] In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a plurality of switches, each switch of the plurality of switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more registers or memory circuits configured to store the plurality of predetermined activation patterns.

[0023] In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more registers or memory circuits configured to store the plurality of predetermined activation patterns. In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, further comprises: an activation pattern selection logic circuit configured to select the selected predetermined activation pattern from the one or more registers or memory circuits; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selected predetermined activation pattern. In a representative IVUS catheter embodiment, also for example and without limitation, each analog switch, of the plurality of analog switches, comprises a transmission gate configured, when in an on state, to conduct an activation signal or voltage to the selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements.

[0024] In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is configured to respond to a command to simultaneously or concurrently switch, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches correspondingto a selected predetermined activation pattern of the plurality of predetermined activation patterns.

[0025] A representative method of operating the intravascular ultrasound catheter apparatus is also disclosed, comprising: using a selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, receiving a selection of an activation pattern, of the plurality of predetermined activation patterns; using the selected ultrasonic transducer controller, receiving an on command; in response to the on command, using the selected ultrasonic transducer controller, simultaneously or concurrently switching, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selected activation pattern; and using the selected ultrasonic transducer controller, receiving one or more activation signals or voltages and transmitting the received one or more activation signals or voltages through the subset of analog switches to the selection of ultrasonic transducer elements of the selected activation pattern.

[0026] A representative method of operating the intravascular ultrasound catheter may further comprise: using the selected ultrasonic transducer controller, receiving an off command; and in response to the off command, using the selected ultrasonic transducer controller, simultaneously or concurrently switching, to an off and nonconducting state, the subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selected activation pattern.

[0027] In a representative embodiment, an IVUS catheter may further comprise: a catheter control connector arranged proximally within the elongated housing and coupled to the plurality of ultrasonic transducer controllers; a plurality of analog transmit and receive coaxial wires or lines coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; a plurality of supply voltage lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; and a plurality of digital logic lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers. In a representative IVUS catheter embodiment, also for example and without limitation, the plurality of ultrasonic transducer elements comprises at least forty to eighty ultrasonic transducer elements, the plurality of ultrasonic transducer controllers comprises at least four to six ultrasonic transducer controllers, the plurality of analog transmit and receive coaxial wires or lines comprises four or fewer analog transmit and receive coaxial wires or lines, the plurality of supply voltage lines or wires comprises four or fewer supply voltage lines or wires, and the plurality of digital logic lines or wires comprises four or fewer digital logic lines or wires.

[0028] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is coupled in series with the corresponding subset of ultrasonic transducer elements.

[0029] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is operable independently from each of the other ultrasonic transducer controllers of the plurality of ultrasonic transducer controllers.

[0030] In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is coupled in series with the corresponding subset of ultrasonic transducer elements; each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is coupled in parallel with all other ultrasonic transducer controllers, of the plurality of ultrasonic transducer controllers; and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is operable independently from each of the other ultrasonic transducer controllers of the plurality of ultrasonic transducer controllers.

[0031] In a representative IVUS catheter embodiment, each corresponding subset of the plurality of ultrasonic transducer elements comprises a plurality of serially or sequentially adjacent ultrasonic transducer elements.

[0032] In a representative embodiment, an intravascular ultrasound (IVUS) system may comprise: an IVUS console comprising: a processor configured to generate a plurality of activation signals and a plurality of addressable commands; a host communication interface coupled to the processor, the host communication interface configured to transmit the plurality of activation signals and the plurality of addressable commands; an image display coupled to the processor; and a first memory circuit coupled to the processor; a patient interface ultrasound module coupleable to the host communication interface; and an IVUS catheter removably coupleable to the patient interface ultrasound module, the IVUS catheter comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command of theplurality of addressable commands, to switch or conduct one or more activation signals, of the plurality of activation signals, to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

[0033] In a representative system embodiment, for example and without limitation, the plurality of ultrasonic transducer controllers are further configured to switch the one or more activation signals to the one or more ultrasonic transducer elements to generate the focused ultrasonic beam having a user-selectable (and / or user-programmable) focal point, focal distance or focal length and a user-selectable or user-programmable scan line center. In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to switch the one or more activation signals to the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures of the ultrasonic transducer assembly.

[0034] In a representative system embodiment, each sub-aperture, of the plurality of sub-apertures, is offset from an adjacent sub-aperture, of the plurality of sub-apertures, by one ultrasonic transducer element of the plurality of ultrasonic transducer elements. In a representative system embodiment, for example and without limitation, the plurality of ultrasonic transducer controllers are further configured to switch the one or more activation signals to one or more ultrasonic transducer elements of the selected sub-aperture, followed by switching the one or more activation signals to one or more ultrasonic transducer elements of a next sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, to successively generate a series of focused ultrasonic beams around the entire circumferential array of the plurality of ultrasonic transducer elements. In a representative system embodiment, each sub-aperture, of the plurality of sub-apertures, comprises a predetermined number of adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements.

[0035] In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected subaperture of a plurality of sub-apertures of the ultrasonic transducer assembly, wherein each subaperture, of the plurality of sub-apertures, comprises a predetermined number of serially or sequentially adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements. In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically switch or conduct the one or more activationsignals to the one or more ultrasonic transducer elements of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0036] In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to switch or conduct the one or more activation signals to the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns. In a representative system embodiment, each predetermined activation pattern, of the plurality of predetermined activation patterns, comprises: a selection of ultrasonic transducer elements for activation, from the plurality of ultrasonic transducer elements; an ordering of the selected ultrasonic transducer elements for activation; and a plurality of predetermined time delays for sequential activation of the ordered, selected ultrasonic transducer elements.

[0037] In a representative system embodiment, for example and without limitation, the processor is further configured to store the plurality of predetermined activation patterns in the first memory circuit. In a representative system embodiment, also for example and without limitation, the processor is configured to determine the plurality of predetermined activation patterns and to transmit the selection of ultrasonic transducer elements for activation, for each predetermined activation pattern of the plurality of predetermined activation patterns, via the patient interface ultrasound module, to one or more corresponding ultrasonic transducer controllers of the plurality of ultrasonic transducer controllers. In a representative system embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises one or more second memory circuits or registers, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to receive a selection of ultrasonic transducer elements for activation for each received predetermined activation pattern, of the plurality of predetermined activation patterns, and to store the selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns, in the one or more second memory circuits or registers.

[0038] In a representative system embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a plurality of switches, each switch of the plurality of switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store the selectionof ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns.

[0039] In a representative system embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store the selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns. In a representative system embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, further comprises: an activation pattern selection logic circuit configured to select the selection of ultrasonic transducer elements for activation from the one or more second memory circuits or registers; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selection of ultrasonic transducer elements for activation. In a representative system embodiment, also for example and without limitation, each analog switch, of the plurality of analog switches, comprises a transmission gate configured, when in an on state, to conduct an activation signal or voltage to the selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements.

[0040] In a representative system embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is configured to respond to an on command to simultaneously or concurrently switch, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selection of ultrasonic transducer elements for activation of the plurality of predetermined activation patterns.

[0041] A representative method of operating the intravascular ultrasound system is also disclosed, comprising: using the IVUS console, transmitting a memory pointer to a selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers; using the IVUS console, transmitting an on command to the selected ultrasonic transducer controller; using the selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, receiving the memory pointer and the on command; using the selected ultrasonic transducer controller, in response to the memory pointer, selecting from the one or more second memory circuits or registers a selection of ultrasonic transducer elements foractivation corresponding to the memory pointer; and using the selected ultrasonic transducer controller, in response to the on command, simultaneously or concurrently switching, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selection of ultrasonic transducer elements for activation.

[0042] The representative method of operating the intravascular ultrasound system may further comprise: using the IVUS console, transmitting a first activation signal or voltage to the selected ultrasonic transducer controller to simultaneously and symmetrically activate a first pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures; and following one or more predetermined time delays, using the IVUS console, transmitting a second or next activation signal or voltage to the selected ultrasonic transducer controller to simultaneously and symmetrically activate a second or next pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of a plurality of sub-apertures. The representative method of operating the intravascular ultrasound system may further comprise: following transmission of a last activation signal or voltage, using the IVUS console, receiving, through the subset of analog switches in the on and conducting state, one or more ultrasound signals from the corresponding subset of the plurality of ultrasonic transducer elements.

[0043] The representative method of operating the intravascular ultrasound system may further comprise: using the IVUS console, transmitting an off command to the selected ultrasonic transducer controller; and using the selected ultrasonic transducer controller, in response to the off command, simultaneously or concurrently switching, to an off and nonconducting state, the subset of analog switches.

[0044] Another representative method of operating the intravascular ultrasound system is also disclosed, comprising: in a first digital phase, using the selected ultrasonic transducer controller, switching one or more subsets of analog switches to an on and conducting state; in an analog phase when the one or more subsets of analog switches are in the on and conducting state, using the IVUS console, transmitting a plurality of activation signals to the selected ultrasonic transducer controller to sequentially activate one or more pairs of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures, and following transmission of the plurality of activation signals, using the IVUS console, receiving, through the subset of analog switches in the on and conducting state, one or more ultrasound signals from the corresponding subset of the plurality of ultrasonic transducer elements; and ina second digital phase following reception of the one or more ultrasound signals, using the selected ultrasonic transducer controller, switching the one or more subsets of analog switches to an off and nonconducting state.

[0045] A representative method of using the IVUS system in a human or veterinary subject is also disclosed, comprising: using the IVUS console, determining or selecting one or more activation patterns for one or more ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, having one or more selected focal points and scan lines; using the IVUS console, loading the one or more activation or energizing patterns into the IVUS catheter; inserting and positioning the IVUS catheter at a first selected or desired vasculature location in the subject; using the IVUS console, activating the one or more ultrasonic transducer elements according to the selected activation pattern; using the IVUS console, receiving signals via the IVUS catheter from reflected ultrasound waves; and when no additional images are to be obtained, removing the IVUS catheter from the subject.

[0046] The representative method of using the IVUS system may further comprise: when additional images are to be obtained, pulling the IVUS catheter to a second or next selected or desired vasculature location in the subject; using the IVUS console, activating the one or more ultrasonic transducer elements according to the selected activation pattern; and using the IVUS console, receiving signals via the IVUS catheter from reflected ultrasound waves.

[0047] In a representative system embodiment, also for example and without limitation, the IVUS console is further configured to sequentially transmit, according to one or more predetermined time delays, a plurality of activation signals to the selected ultrasonic transducer controller to sequentially activate one or more pairs of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0048] In a representative embodiment, an intravascular ultrasound (IVUS) system may comprise: an IVUS console comprising: a processor configured to generate a plurality of activation signals or voltages, a plurality of addressable commands, and a plurality of predetermined activation patterns; a host communication interface coupled to the processor, the host communication interface configured to transmit the plurality of activation signals, the plurality of addressable commands, and the plurality of predetermined activation patterns; an image display coupled to the processor; and a first memory circuit coupled to the processor, the first memory circuit configured to store a plurality of predetermined activation patterns;a patient interface ultrasound module coupleable to the host communication interface; and an IVUS catheter removably coupleable to the patient interface ultrasound module, the IVUS catheter comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with a catheter guidewire, the tubular inner wall having a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command of the plurality of addressable commands, to switch or conduct one or more activation signals or voltages, of the plurality of activation signals or voltages, to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements, according to a selected, received predetermined activation pattern of the plurality of predetermined activation patterns, to generate a focused ultrasonic beam, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store a selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns.

[0049] In a representative embodiment, an intravascular ultrasound (IVUS) catheter, apparatus insertable into a human or veterinary subject along a catheter guidewire, may comprise: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with the catheter guidewire, the tubular inner wall having a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command, to switch or conduct one or more activation signals to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns, to generate a focused ultrasonic beam, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; one or more second memory circuits or registers configured to store a selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns; an activation pattern selection logic circuit configured to select the selection of ultrasonic transducer elements for activation from the one or more second memory circuits or registers; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selection of ultrasonic transducer elements for activation.

[0050] In a representative embodiment, an intravascular ultrasound (IVUS) catheter apparatus may comprise: an elongated housing having a first, distal end and a second, proximalend; a plurality of ultrasonic transducer elements arranged distally in a circumferential array around the elongated housing; and a plurality of ultrasonic transducer controllers distributed within the elongated housing, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

[0051] In a representative IVUS catheter embodiment, the plurality of ultrasonic transducer controllers are coupled in parallel to each other and in series with the plurality of ultrasonic transducer elements.

[0052] In a representative IVUS catheter embodiment, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures of the ultrasonic transducer assembly. In a representative IVUS catheter embodiment, the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the selected sub-aperture, followed by activating one or more ultrasonic transducer elements of a next adjacent sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, to successively generate a series of ultrasonic beams around the entire circumferential array.

[0053] In a representative IVUS catheter embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly. In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a first pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly, followed by simultaneously and symmetrically activating, according to one or more predetermined time delays, a second or next pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonictransducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0054] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to sequentially activate a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly. In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to sequentially activate, according to one or more predetermined time delays, a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of subapertures of the ultrasonic transducer assembly, to generate a focused ultrasonic beam having a predetermined focal point. In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to sequentially activate, according to one or more predetermined time delays, a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected subaperture of the plurality of sub-apertures of the ultrasonic transducer assembly, to generate a focused ultrasonic beam having a predetermined scan line center.

[0055] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns. In a representative embodiment, each predetermined activation pattern, of the plurality of predetermined activation patterns, comprises: a selection of ultrasonic transducer elements for activation, from the plurality of ultrasonic transducer element; an ordering of the selected ultrasonic transducer elements for activation; and a plurality of predetermined time delays for sequential activation of the ordered, selected ultrasonic transducer elements.

[0056] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to store one or more portions of the plurality of predetermined activation patterns in one or more memory circuits or registers.

[0057] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a plurality of switches, each switch of the plurality of switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more registers or memory circuits configured to store one or more portions of the plurality of predetermined activation patterns.

[0058] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches; and one or more registers or memory circuits configured to store one or more portions of the plurality of predetermined activation patterns.

[0059] In another representative IVUS catheter embodiment, also for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, further comprises: an activation pattern selection logic circuit configured to select the selected predetermined activation pattern from the one or more registers or memory circuits; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selected predetermined activation pattern.

[0060] In a representative embodiment, an intravascular ultrasound (IVUS) catheter apparatus may comprise: an elongated housing having a first, distal end and a second, proximal end; a catheter control connector arranged proximally within the elongated housing; a plurality of ultrasonic transducer elements arranged distally in a circumferential array around the elongated housing, the plurality of ultrasonic transducer elements comprising a plurality of subsets of ultrasonic transducer elements; and a plurality of ultrasonic transducer controllers coupled to the catheter control connector, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements of the plurality of subsets of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements according to a predetermined activation pattern, for a selected sub-aperture of the ultrasonic transducer assembly, to generate a focused ultrasonic beam having a selected focal point and a selected scan line.

[0061] In a representative embodiment, an intravascular ultrasound (IVUS) system may comprise: an IVUS console comprising: a processor configured to generate a plurality of activation signals and a plurality of addressable commands; a host communication interfacecoupled to the processor, the host communication interface configured to transmit the plurality of activation signals and the plurality of addressable commands; an image display coupled to the processor; and a first memory circuit coupled to the processor; a patient interface ultrasound module coupleable to the host communication interface; and an IVUS catheter coupleable to the patient interface ultrasound module, the IVUS catheter comprising: an elongated housing having a first, distal end and a second, proximal end; a plurality of ultrasonic transducer elements arranged distally in a circumferential array around the elongated housing; and a plurality of ultrasonic transducer controllers distributed within the elongated housing, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of adjacent ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

[0062] In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected subaperture of a plurality of sub-apertures of the ultrasonic transducer assembly, wherein each subaperture, of the plurality of sub-apertures, comprises a predetermined number of adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements and is offset from an adjacent sub-aperture, of the plurality of sub-apertures, by one ultrasonic transducer element of the plurality of ultrasonic transducer elements.

[0063] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the selected sub-aperture, followed by activating one or more ultrasonic transducer elements of a next adjacent sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, to successively generate a series of ultrasonic beams around the entire circumferential array.

[0064] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a plurality of ultrasonic transducerelements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0065] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a first pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly, followed by simultaneously and symmetrically activating, according to one or more predetermined time delays, a second or next pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected subaperture of the plurality of sub-apertures of the ultrasonic transducer assembly

[0066] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to sequentially activate a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected subaperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

[0067] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to sequentially activate, according to one or more predetermined time delays, a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly, to generate a focused ultrasonic beam having a predetermined focal point and a predetermined scan line center.

[0068] In a representative system embodiment, for example and without limitation, in response to one or more addressable commands of the plurality of addressable commands, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns.

[0069] In a representative system embodiment, for example and without limitation, the processor is configured to determine the plurality of predetermined activation patterns and to transmit one or more portions of the plurality of predetermined activation patterns, via thepatient interface ultrasound module, to the plurality of ultrasonic transducer controllers. In a representative system embodiment, for example and without limitation, the processor is further configured to store the plurality of predetermined activation patterns in the first memory circuit. In a representative system embodiment, for example and without limitation, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to store the one or more portions of the plurality of predetermined activation patterns in one or more second memory circuits or registers.

[0070] Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The objects, features and advantages of the present invention will be more readily appreciated upon reference to the following disclosure when considered in conjunction with the accompanying drawings, wherein like reference numerals are used to identify identical components in the various views, and wherein reference numerals with alphabetic characters are utilized to identify additional types, instantiations or variations of a selected component embodiment in the various views, in which:

[0072] Figure (or “FIG.”) 1 is a representative ultrasound image illustrating an ultrasonic beam generated by a prior art IVUS catheter.

[0073] Figure (or “FIG.”) 2 is schematic diagram illustrating representative diverging element-centered scan lines generated by a prior art IVUS catheter.

[0074] Figure (or “FIG.”) 3 is a representative ultrasound image illustrating a focused ultrasonic beam generated by representative embodiments of an IVUS catheter in accordance with the disclosure herein.

[0075] Figure (or “FIG.”) 4 is an electrical block diagram illustrating a representative embodiment of an IVUS system in accordance with the disclosure herein.

[0076] Figure (or “FIG.”) 5 is an electrical block diagram illustrating a representative embodiment of an IVUS (host) console in accordance with the disclosure herein.

[0077] Figure (or “FIG.”) 6 is an electrical block diagram illustrating a representative embodiment of a patient interface ultrasound module (“PIUM”) in accordance with the disclosure herein.

[0078] Figure (or “FIG.”) 7 is a first electrical block diagram illustrating a representative embodiment of an IVUS catheter in accordance with the disclosure herein.

[0079] Figure (or “FIG.”) 8 is a second, more detailed electrical block diagram illustrating a representative embodiment of an IVUS catheter in accordance with the disclosure herein.

[0080] Figure (or “FIG.”) 9, divided into FIG. 9A and FIG. 9B and collectively referred to as FIG. 9, is an isometric view illustrating a representative first embodiment of an IVUS catheter in accordance with the disclosure herein.

[0081] Figure (or “FIG.”) 10 is an isometric cut-away view illustrating a representative catheter control connector of a representative first or second embodiment of an IVUS catheter in accordance with the disclosure herein.

[0082] Figure (or “FIG.”) 11 is a partial isometric view illustrating a representative inner tubular wall with a plurality of radiopaque markers of the representative first embodiment of the IVUS catheter in accordance with the disclosure herein.

[0083] Figure (or “FIG.”) 12 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) illustrating a representative circumferential ultrasonic transducer array of the representative first embodiment of the IVUS catheter in accordance with the disclosure herein.

[0084] Figure (or “FIG.”) 13 is a cross-sectional view (through the B - B’ plane ofFIG. 9A) illustrating a representative circumferential array of a plurality of ultrasonic transducer controllers of an ultrasonic transducer assembly of the representative first embodiment of the IVUS catheter in accordance with the disclosure herein.

[0084] Figure (or “FIG.”) 14 is a cross-sectional view (through the C - C’ plane and D- D’ plane of FIG. 9A) illustrating representative radiopaque markers arranged on the circumference of the inner tubular wall of the representative first embodiment of the IVUS catheter in accordance with the disclosure herein.

[0086] Figure (or “FIG.”) 15 is an isometric view illustrating a representative second embodiment of an IVUS catheter in accordance with the disclosure herein.

[0087] Figure (or “FIG.”) 16 is a cross-sectional view (through the E - E’ plane ofFIG. 15) illustrating a representative circumferential ultrasonic transducer array of the representative second embodiment of the IVUS catheter in accordance with the disclosure herein.

[0088] Figure (or “FIG.”) 17 is an isometric view illustrating a representative ultrasonic transducer assembly circuit board and circuit board layout of the representative first or second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0089] Figure (or “FIG.”) 18 is a partial cut-away and cross-sectional view (through the B - B’ plane of FIG. 15) and electrical block diagram illustrating a representative ultrasonic transducer assembly with representative and distributed ultrasonic transducer controllers of therepresentative second embodiment of the IVUS catheter in accordance with the disclosure herein.

[0090] Figure (or “FIG.”) 19 is an electrical block diagram illustrating a representative embodiment of an ultrasonic transducer controller of the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0091] Figure (or “FIG.”) 20 is an electrical block diagram illustrating a representative embodiment of a crosspoint switch matrix for the representative embodiment of the ultrasonic transducer controller of the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0092] Figures (or “FIGs.”) 21A and 21B (collectively referred to as “FIG. 21”) is a flow chart illustrating a representative method embodiment for controlling the switching and energizing of the representative circumferential ultrasonic transducer array for dynamic beamforming and ultrasound signal reception from the representative circumferential ultrasonic transducer array with intravascular imaging using the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0093] Figure (or “FIG.”) 22 is a partial cross-sectional view (through the A - A’ plane of FIG. 9A) and is a partial cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential ultrasonic transducer array and dynamically variable sub-aperture selection of the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0094] Figure (or “FIG.”) 23 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array of ultrasonic transducer elements and a partially exploded view illustrating focal delays with a scan line center and focal point for a selected non-element centered sub-aperture for the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0095] Figure (or “FIG.”) 24 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array of ultrasonic transducer elements and a partially exploded view illustrating focal delays with a scan line center and focal point for a selected element centered sub-aperture for the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0096] Figure (or “FIG.”) 25 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array of ultrasonic transducer elements and a partially explodedview illustrating a focus delay calculation for a dynamically selectable focal point for the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0097] Figure (or “FIG.”) 26 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array of ultrasonic transducer elements and a partially exploded view illustrating a plurality of dynamically selectable focal points for the representative first and second embodiments of the IVUS catheter in accordance with the disclosure herein.

[0098] Figure (or “FIG.”) 27 is a flow chart illustrating a method of dynamic beamforming with intravascular imaging using the representative first or second embodiments of the IVUS catheter in accordance with the disclosure herein.DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

[0099] While the present invention is susceptible of embodiment in many different forms, there are shown in the drawings and will be described herein in detail specific exemplary embodiments thereof, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. In this respect, before explaining at least one embodiment consistent with the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of components set forth above and below, illustrated in the drawings, or as described in the examples. Methods and apparatuses consistent with the present invention are capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract included below, are for the purposes of description and should not be regarded as limiting.

[0100] FIG. 1 is an ultrasound image illustrating an ultrasonic beam 20 generated by a prior art IVUS catheter, which is diffuse and comparatively poorly focused. As mentioned above, the insonification beam pattern of a single small ultrasonic transducer element is diffuse and has little focus. This results in comparatively low imaging resolution, with no capability to produce a higher resolution focal zone.

[0101] FIG. 2 is schematic diagram illustrating diverging element-centered scan lines generated by a prior art IVUS catheter having multiple ultrasonic transducer (e.g., PZT) elements 250 arranged in a circumferential manner. Existing solid state IVUS systems utilize single ultrasonic transducer element transmit at a time and have no capability for electronic focusing, and as a result, the existing solid state IVUS systems can only generate diverging“scanlines” 80 centered on the physical ultrasonic transducer elements 275, as illustrated. With a circumferential array of ultrasonic transducer elements, given the curvature 25 of the catheter, the scanlines 80 diverge from one another (35), which constrains the scanline density and therefore the spatial resolution of the resulting image.

[0102] FIG. 3 is a representative ultrasound image illustrating a focused ultrasonic beam 30 generated by representative embodiments of an IVUS catheter 200, 200A in accordance with the disclosure herein. As discussed in greater detail below, the representative embodiments of an IVUS catheter 200, 200A have an array 245 of a plurality of ultrasonic transducer elements 250 arranged in a circumferential manner, i.e., spaced-apart circumferentially along or about the IVUS catheter 200, 200A, such as illustrated in FIGs. 9A, 12, 15 and 16 (or, stated another way, the ultrasonic transducer elements 250 are spaced apart from each other along a circle (or arc) formed at a predetermined or otherwise fixed radial (75) distance from the longitudinal center or axis 85 of the IVUS catheter 200, 200A).

[0103] It should be noted that, in accordance with typical usage in the IVUS imaging field, while each individual ultrasonic transducer element 250 is a transducer which emits ultrasonic (or ultrasound) waves and receives reflected ultrasonic (or ultrasound) waves, they are typically referred to as “elements” 250, while the entire totality of ultrasonic transducer elements 250 is typically referred to as the overall “transducer”. Accordingly, as utilized herein, an ultrasound (or ultrasonic) transducer element 250 or element 250 refers to the single, individual ultrasound (or ultrasonic) transducer element (e.g., a piezoelectric zirconate transducer (PZT) element), while the collective group of ultrasonic transducer elements 250 is referred to herein as an array 245 of ultrasonic transducer elements 250 (i.e., an ultrasonic transducer array 245). Also in accordance with typical usage in the optical and imaging fields, for a compound device such as an IVUS catheter 200, 200A having a plurality of individually selectable ultrasonic transducer elements 250, as discussed in greater detail below, selected subsets of the plurality of the ultrasonic transducer elements 250 are referred to as “subapertures” 275; however, these selected subsets of the plurality of the ultrasonic transducer elements 250 may be referred to equivalently as “apertures”, and any and all such variations are considered equivalent and within the scope of the disclosure.

[0104] As mentioned above, it should be noted that, as utilized herein, unless specifically indicated to the contrary or as required by the context, the terms “ultrasonic” and “ultrasound” are generally utilized interchangeably and equivalently herein, and no limitation is intended or should be inferred from usage of “ultrasonic” rather than “ultrasound” and vice- versa. For example and without limitation, any reference to an ultrasonic transducer or ultrasonic transducer element 250 should be understood to mean and include an ultrasoundtransducer or ultrasound transducer element 250, and vice-versa. Also for example and without limitation, any reference to an ultrasonic transducer controller 265 should be understood to mean and include an ultrasound transducer controller 265, and vice-versa. Also for example and without limitation, any reference to an ultrasonic beam 20, 30 or wave should be understood to mean and include an ultrasound beam 30, 30 or wave, and vice-versa.Accordingly, as utilized herein, an ultrasonic transducer element 250 also may be referred to equivalently and variously as an ultrasonic transducer element 250 or as an ultrasound transducer element 250, and any reference to an ultrasonic transducer controller 265 should be understood to mean and include an ultrasound transducer controller 265 and vice-versa, for example and without limitation.

[0105] Specifically, in the various representative embodiments, not all of the ultrasonic transducer elements 250 of the IVUS catheter 200, 200A are energized and transmitting at the same time. Instead, a subset of the plurality of the ultrasonic transducer elements 250 are energized, in groups referred to as sub-apertures (or, equivalently, apertures) 275 (illustrated and discussed below with reference to FIGs. 12, 16 and 22 - 26), either with each ultrasonic transducer element 250 of any selected sub-aperture 275 individually and separately energized in a selected sequence with a selected delay ( .e., the energizing of the ultrasonic transducer element 250 having an offset time from the energizing of other ultrasonic transducer elements 250 of the selected sub-aperture 275, or with symmetrical pairs of ultrasonic transducer elements 250 of any selected sub-aperture 275 collectively and simultaneously energized in a selected sequence with a selected delay ( .e., the energizing of the pair of ultrasonic transducer elements 250 having an offset time from the energizing of other ultrasonic transducer elements 250 of the selected sub-aperture 275). This energizing sequence of the ultrasonic transducer elements 250 of the selected sub-aperture 275 with selected delays creates geometric delays in the energizing of the ultrasonic transducer elements 250 and resulting ultrasound transmission, thereby generating a corresponding ultrasonic wavefront pattern resulting in a dynamically focused ultrasonic beam 30. As discussed in greater detail below, FIG. 3 illustrates the effect of using such a sub-aperture 275 of the ultrasonic transducer elements 250 with appropriate geometric delays, in this illustration, to focus the ultrasonic beam 30 at 10 mm, for example and without limitation. As illustrated, the energy is much more controlled laterally and the intensity of sonification pattern is far greater than the single element case illustrated in FIG. 1. Those having skill in the art will recognize that a wide variety of schemes, selections, orderings, and timings of energizing of the ultrasonic transducer elements 250 are available, and any and all such variations are considered equivalent and within the scope of the disclosure. Those having skill in the art also will recognize that awide variety of the amounts or numbers of the ultrasonic transducer elements 250 being energized are also available, and any and all such variations are also considered equivalent and within the scope of the disclosure. Those having skill in the art also will recognize that a wide variety of the amounts or numbers of the ultrasonic transducer elements 250 included in a catheter 200, 200A are also available, and any and all such variations are also considered equivalent and within the scope of the disclosure.

[0106] The IVUS imaging system 100, 100A, with multi -element active sub-apertures275 and dynamic focus delay beamforming, can be used to position ultrasonic scanlines at any point along the active sub-aperture 275, dynamically and arbitrarily. As an example, scanlines may be positioned on ultrasonic transducer elements 250 of the selected sub-aperture 275 elements or in between ultrasonic transducer elements 250 of the selected sub-aperture 275, as illustrated and discussed below with reference to FIGs. 23 and 24. The representative embodiments of the IVUS catheter 200, 200A and IVUS system 100, 100A thereby increase the acquired scanline density, resulting in better spatial resolution. This increase is particularly helpful further away from the ultrasonic transducer elements 250, counteracting the divergence of the prior art scanlines (which diverge due to tightly curved geometry of the catheter, such as illustrated in FIG. 2).

[0107] FIG. 4 is an electrical block diagram illustrating a representative embodiment of an IVUS system 100, 100A in accordance with the disclosure herein. FIG. 5 is an electrical block diagram illustrating a representative embodiment of an IVUS (host) console 150 (equivalently referred to herein more simply as an “IVUS console” 150) in accordance with the disclosure herein. FIG. 6 is an electrical block diagram illustrating a representative embodiment of a patient interface ultrasound module (“PIUM”) 105 in accordance with the disclosure herein. FIG. 7 is a first electrical block diagram illustrating a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 8 is a second, more detailed electrical block diagram illustrating a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein.

[0108] FIG. 9, divided into FIG. 9A and FIG. 9B, is an isometric view illustrating a representative first embodiment of an IVUS catheter 200 in accordance with the disclosure herein. FIG. 10 is an isometric cut-away view illustrating a representative catheter control connector 210A and connector body (or plug) 455 for the representative first and second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 11 is a partial isometric view illustrating a portion of a representative inner tubular wall 380 with a plurality of radiopaque markers 375 (e.g., markers) of the first embodiment of the IVUS catheter 200 in accordance with the disclosure herein. FIG. 12 is a cross-sectional view(through the A - A’ plane of FIG. 9A) illustrating a representative circumferential ultrasonic transducer array 245 of an ultrasonic transducer assembly 205 of the representative first embodiment of the IVUS catheter 200 in accordance with the disclosure herein. FIG. 13 is a cross-sectional view (through the B - B’ plane of FIG. 9A) illustrating a representative circumferential array of a plurality of ultrasonic transducer controllers 265 of an ultrasonic transducer assembly 205 of the representative first embodiment of the IVUS catheter 200 in accordance with the disclosure herein. FIG. 14 is a cross-sectional view (through the C - C’ plane and D - D’ plane of FIG. 9A) illustrating representative radiopaque markers 375 arranged on the circumference of the inner tubular wall 380 of the representative first embodiment of the IVUS catheter 200 in accordance with the disclosure herein.

[0109] FIG. 15 is an isometric view illustrating a representative second embodiment of an IVUS catheter 200A in accordance with the disclosure herein. FIG. 16 is a cross- sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential ultrasonic transducer array 245 of an ultrasonic transducer assembly 205 of the representative second embodiment of the IVUS catheter 200A in accordance with the disclosure herein. FIG. 17 is an isometric view illustrating a representative ultrasonic transducer assembly circuit board 460 and circuit board layout of the representative first or second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 18 is a partial cut-away and cross-sectional view (through the B - B’ plane of FIG. 15) and electrical block diagram illustrating a representative ultrasonic transducer assembly 205A with representative and distributed ultrasonic transducer controllers 265 of the representative second embodiment of the IVUS catheter 200A in accordance with the disclosure herein.

[0110] FIG. 19 is an electrical block diagram illustrating a representative embodiment of an ultrasonic transducer controller 265 of the representative first and second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 20 is an electrical block diagram illustrating a representative embodiment of a crosspoint switch matrix 325 for the representative embodiment of the ultrasonic transducer controller 265 of the representative first and second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 21 is a flow chart illustrating a representative method 500 embodiment for controlling the switching and energizing of the representative circumferential ultrasonic transducer array 245 for dynamic beamforming and ultrasound signal reception from the representative circumferential ultrasonic transducer array 245 with intravascular imaging using the representative first and second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 22 is a partial cross-sectional view (through the A - A’ plane of FIG. 9A) and is a partial cross-sectional view (through the E - E’ plane of FIG. 15)illustrating a representative circumferential ultrasonic transducer array 245 and dynamically variable sub-aperture selection of the representative first and second embodiments of the IVUS catheter 200, 200A in accordance with the disclosure herein.

[0111] Referring to FIG. 4, a representative embodiment of an IVUS system 100 comprises an IVUS catheter 200, a patient interface ultrasound module (“PIUM”) 105, and an IVUS console 150 (e.g., a host console or a host device). The IVUS catheter 200 is electrically coupleable or connected to the PIUM 105 via conductive pins, lines, wires or bus 180 (such as via conductive pins 180A of a catheter control connector 210A), and in turn, the PIUM 105 is electrically coupleable or connected to the IVUS console 150 via lines, wires or bus 182. A representative embodiment of an IVUS system 100A comprises an IVUS catheter 200A, which is electrically coupleable or connected to a patient interface ultrasound module (“PIUM”) 105 via conductive pins, lines, wires or bus 180 (such as via conductive pins 180A of a catheter control connector 210A), which in turn is electrically coupleable or connected to an IVUS console 150 (e.g., a host console or a host device) via lines, wires or bus 182.

[0112] Referring to FIG. 5, a representative embodiment of an IVUS console 150(IVUS (host) console 150) comprises a user interface 140, a host communication interface 135, a processor 145, and an image output display 155. In a representative embodiment, the IVUS console 150 also typically includes a memory circuit 185, such as to store received data for ultrasound image formation and to store various activation patterns (for loading into the IVUS catheter 200, 200A, as described in greater detail below), which are coupled for selected communication via lines, wires or bus 184, for example and without limitation. The processor 145 generates the data or signaling for the ultrasonic transmit beamforming (using a transmit (Tx) beamforming processing module 143, for example and without limitation), transmitted through the host communication interface 135 to the PIUM 105 and ultimately to the IVUS catheter 200, 200A. The processor 145 may also perform image processing (using an image output processing module 141, for example and without limitation), generating the data or signaling for the ultrasound image to be displayed on the image output display 155, such as for viewing in real time by medical personnel, using received ultrasonic data transmitted from the IVUS catheter 200, 200A through the PIUM 105 and host communication interface 135. Medical personnel also interact with the IVUS console 150 via the user interface 140, which may be implemented as a keyboard, touchscreen, and / or mouse / trackball (not separately illustrated), for example and without limitation, such as for input and selection of data (such as an energizing sequence) for the transmit beamforming and image selection for output on the image output display 155, also for example and without limitation.

[0113] Referring to FIG. 6, a representative embodiment of a patient interface ultrasound module (“PIUM”) 105 comprises, for example and without limitation: a PIUM communication interface 130 (for communication with the IVUS console 150 via the host communication interface 135), a controller 125, a signal (image) processor 120, a power supply 115, and a PIUM connector 110 (for communication (via pins, cable, wires or bus 180, 180A) with the IVUS catheter 200, 200A, typically via a mating or corresponding catheter control connector 210, 210A illustrated in FIGs. 7 and 10), which are coupled for selected communication via lines, wires or bus 186. In a representative embodiment, the PIUM 105 also typically includes a memory circuit 190, such as to store received data for ultrasound image formation and possibly also to store various activation patterns (for loading into the IVUS catheter 200, 200A, as described in greater detail below), for example and without limitation. The controller 125 may typically include an ultrasound transmit pulser circuit 160 to generate activation signals or otherwise provide, transmit or relay other data (such as command signals and / or activation patterns) to the IVUS catheter 200, 200A (including relaying or otherwise providing the data, commands and activation signaling generated and provided by the IVUS console 150), and an “analog front end” comprising an ultrasound signal receiver 165 to receive and amplify signals generated by the IVUS catheter 200, 200A from received ultrasound reflections, a filter such as a bandpass filter 168 to provide bandpass filtering to the received signal, and an analog -to-digital converter (“ADC”) 170, to convert the received analog ultrasound signal to digital ultrasound signal data for signal processing by the signal (image) processor 120 and / or the processor 145, which also may be coupled for selected communication via lines, wires or bus 188, in addition to or in lieu of using lines, wires or bus 186. The bandpass filter 168 may be an analog filter (when arranged to provide bandpass filtering of the received analog signal, as illustrated) or a digital filter (when arranged to provide digital bandpass filtering of the digitized received signal, not separately illustrated).The power supply 115 provides appropriate DC power, ground, and any desired or selected bias voltage to the IVUS catheter 200, 200A, also via the PIUM connector 110 and catheter control connector 210, coupled or couplable via cable, wires or bus 180).

[0114] Referring to FIGs. 7 - 18, a representative embodiment of an IVUS catheter200, 200A comprises a catheter housing 240, 240A, an ultrasonic transducer assembly 205 (comprising an array 245 of a plurality of ultrasonic transducer elements 250 (generally arranged or coupled near a distal end 207 of the IVUS catheter 200, 200A) and a plurality of ultrasonic transducer controllers 265 (also arranged within the catheter housing 240, 240A), and a catheter control connector 210, 210A (generally arranged or coupled at or near a proximal end 209 of the IVUS catheter 200, 200A), for example and without limitation. Thecatheter housing 240, 240A (shown in cross-section in FIGs. 12 - 14 and 16), in representative embodiments, is a flexible, generally elongate (along or defining a longitudinal dimension 85) and tubular or otherwise cylindrically-shaped housing 240, 240A, for example and without limitation, and may have a form factor and be fabricated as known in the art. The catheter control connector 210, 210A is coupled to or integrally formed with the catheter housing 240, 240A, and provides for electrical coupling to the PIUM connector 110 of the PIUM 105 via cable, wires or bus 180, such as via conductive pins 180A. Additional components may also be included in an IVUS catheter 200, 200A, such as features or structures for slidably coupling with a catheter guidewire 360, not separately illustrated in FIGs. 15 and 16, for example and without limitation.

[0115] The IVUS catheter 200 and the IVUS catheter 200A have several structural differences. First, the IVUS catheter 200 includes a tubular inner wall (or extrusion) 380, with the tubular inner wall 380 being spaced apart radially from the catheter housing 240, toward and generally extending along the central or center longitudinal axis 85. A first, outer lumen 385 is formed between the catheter housing 240 and the tubular inner wall 380. The tubular inner wall (or extrusion) 380 has a second, inner lumen 390. As illustrated in FIGs. 9A and 9B, a guidewire 360 is insertable into the second, inner lumen 390, and the IVUS catheter 200 is thereby slidable along the guidewire 360, such as for following a guidewire inserted into a vein or artery of a subject.

[0116] Second, as illustrated in FIG. 14, the various signaling, power, and ground wires or cables 220A are arranged within the first, outer lumen 385 of the IVUS catheter 200, for providing signaling, power, and ground to the ultrasonic transducer controllers 265 to selectively energize and receive ultrasound signals from the plurality of the ultrasonic transducer elements 250. In the IVUS catheter 200A, as illustrated in FIG. 16, the signaling, power, and ground wires or cables 220A are arranged and extend longitudinally within a single, central lumen 462 (which also extends longitudinally along the length of the IVUS catheter 200A). For both the IVUS catheter 200 and IVUS catheter 200A, the various signaling, power, and ground wires or cables 220A terminate in the catheter control connector 210, 210A, for coupling to the PIUM 105.

[0117] Third, as illustrated in FIG. 9B, the IVUS catheter 200 includes a handle or grip 365 arranged toward the proximal end 209 of the IVUS catheter 200, for aiding user manipulation of the IVUS catheter 200. As illustrated, the guide wire 360 also passes through a hollow guidewire track 395 of the handle or grip 365, while the various signaling, power, and ground wires or cables 220A are separately arranged within the cable 370 extending from the handle or grip 365 for coupling to the PIUM 105 (via conductive pins 180A). Apart from thesethree structural differences, the IVUS catheter 200 and the IVUS catheter 200A function identically to each other and otherwise include the same components having the same structures and functions, and unless the context so requires or the context clearly indicates to the contrary, any reference to an IVUS catheter 200 will be understood to mean and include the IVUS catheter 200A, and vice-versa.

[0118] Referring to FIGs. 9A, 12, 13, and 17, in a representative embodiment, for either or both of the first and second IVUS catheter 200, 200A embodiments, the plurality of ultrasonic transducer elements 250 generally are arranged adjacent to the ultrasonic transducer controllers 265, and the ultrasonic transducer controllers 265 are coupled to the plurality of ultrasonic transducer elements 250 (as described in greater detail below) and to the signaling, power, and ground wires or cables 220A using a flexible circuit board 460. The plurality of ultrasonic transducer elements 250 are coupled to electrically conductive pads 225A, which are electrically coupled (in groups or subsets) to corresponding ultrasonic transducer controllers 265. The signaling, power, and ground wires or cables 220A are coupled to corresponding electrically conductive pads 470, which are electrically coupled (through impedance matching components 212 (such as resistors 214 and capacitors 216)) to the ultrasonic transducer controllers 265. The electrically conductive pads 470 may be folded back (in the direction indicated by arrow 472), and the flexible circuit board 460 may be rolled into a tubular or cylindrical form (in the circular direction indicated by arrow 474), for inclusion within or coupling to the housing 240, 240A of the IVUS catheter 200, 200A, with the plurality of ultrasonic transducer elements 250 remaining sufficiently exposed on the exterior of the housing 240, 240A for comparatively or relatively unimpeded ultrasound transmission and reception. As a different option, also within the scope of the disclosure, rather than being directly adjacent the plurality of ultrasonic transducer elements 250, the ultrasonic transducer controllers 265 instead may be distributed spaced apart longitudinally within the housing 240A of the IVUS catheter 200A, as illustrated in FIG. 18, for example and without limitation.

[0119] As an option, in a representative embodiment, radiopaque markers, such as radiopaque markers 375, 375A illustrated as having a circular band shape or configuration, for example and without limitation, may be included on or within the IVUS catheter 200, 200A. Evenly spaced radiopaque markers, such as radiopaque markers 375, 375A having a circular band shape or configuration, arranged toward the distal end of an IVUS catheter 200, 200A provide a measurement scale for physicians to measure the local anatomy. These markings allow physicians or other medical personnel to characterize the area for treatment and make informed decisions during their procedure (for example, deciding what size (e.g., length) stent to place in a vessel). As illustrated in FIG. 11, a plurality of radiopaque markers 375 have beenapplied to the outer surface 379 of the tubular inner wall 380. Each of the radiopaque markers 375 extends circumferentially around the tubular inner wall 380 and extends longitudinally along the tubular inner wall 380 by a predetermined and consistent width 378. Each radiopaque marker 375 is also spaced apart from an adjacent radiopaque marker 375 by a predetermined distance 376. For the IVUS catheter 200A, optional radiopaque markers 375 A may be provided on the exterior surface of the housing 240A, as illustrated in FIG. 15. In a representative embodiment, for example and without limitation, each of the radiopaque markers 375, 375A has a circular band shape or configuration, has a thickness or 0.0762 mm (3 / 1000 of an inch) (in the radial dimension), has a width of 2 mm (in the longitudinal dimension), and is spaced apart from any adjacent radiopaque marker 375, 375A by 10 mm (also in the longitudinal dimension).

[0120] These radiopaque markers 375, 375A can indicate to the user the relative location of the IVUS catheter 200, 200A, aid in actuation of the IVUS catheter 200, 200A, or identify certain parts of the IVUS catheter 200, 200A. Individual radiopaque markers 375, 375A can also be printed (e.g., through pad printing) to help visualize certain parts under fluoroscopy. Varying the pattern of the markers (such as bands), or printing other markings such as numbers, can also contribute to a device’s design. Additional embodiments may also include printing or application on different locations and using different mediums. While radiopaque markers 375, 375A can be printed on an inner layer of a IVUS catheter 200, since they will show up under fluoroscopy, non-radiopaque markings can be printed on the outer surface to be visible without imaging technology. Pad printing can also be implemented on non-tubing related materials, such as flat plastic components, to add designs or markings.

[0121] As an example, the plurality of radiopaque markers 375, 375A may be applied to the tubular inner wall 380 or to the exterior surface of the housing 240, 240A, such as through pad printing of a radiopaque ink. In this process, a pad picks up radiopaque ink from a cliche and presses onto the tubular inner wall 380 or the catheter housing 240A tubing to transfer the artwork. The pad then moves laterally, allowing the tubing to roll so ink transfers evenly around the tubing, forming the circular band shape or configuration. Multiple passes may be performed on one tube to increase the thickness of the prints to provide optimal visibility under fluoroscopy, for example and without limitation. Once the desired thickness is achieved, the part is cured to ensure full adhesion of the ink. The output results in consistent, radiopaque markers 375, 375A that are robust enough to withstand further manufacturing processes and also show up brightly under fluoroscopy. Those having skill in the art will recognize that while the radiopaque markers 375, 375 A are illustrated as having a circular band shape or configuration (and may also be referred to as radiopaque markers bands 375, 375 A,the radiopaque markers 375, 375A may have a wide variety of shapes, patterns, configurations, and spacings, in addition to the illustrated spaced-apart circular bands, such as radial or longitudinal stripes, zig-zags, checkerboards, ovals, ellipses, waves, etc., and any and all such variations are considered equivalent and within the scope of the disclosure. Those having skill in the art will also recognize that, in addition to pad printing, the radiopaque markers 375, 375A may be fabricated, applied or otherwise added to the tubular inner wall 380 or to the exterior surface of the housing 240, 240A in a wide variety of ways, such as using decals or other appliques, painting, coating, dipping, spraying, etc., and any and all such variations are considered equivalent and within the scope of the disclosure.

[0122] A representative embodiment of the ultrasonic transducer assembly 205 comprises a plurality of ultrasonic transducer elements 250 arranged (typically spaced apart from each other or abutting each other) as a circumferential array 245 and coupled to a plurality of ultrasonic transducer controllers 265, as discussed in greater detail below. The plurality of ultrasonic transducer elements 250 are arranged as a circumferential array 245, with each ultrasonic transducer element 250 arranged at a predetermined or fixed radial distance 75 (rather than arranged longitudinally), around or about the catheter housing 240, 240A, as illustrated in FIGs. 9, 12, 15 and 16. Not separately illustrated, the ultrasonic transducer assembly 205 may also include other supporting structure and electrical couplings, as may be needed, such as to space apart the ultrasonic transducer elements 250 in the circumferential array 245 and / or further support and secure them to the catheter housing 240, 240A, for example and without limitation. As mentioned above, the ultrasound (or ultrasonic) transducer elements 250 also may be are referred to equivalently herein as ultrasound (or ultrasonic) transducers 250. The ultrasound (or ultrasonic) transducer elements 250 may be any type or kind of ultrasound (or ultrasonic) transducer elements, including piezoelectric zirconate transducer elements (PZTs), capacitive micromachined ultrasonic transducer elements (CMUTs), and / or piezoelectric micromachined ultrasonic transducer elements, for example and without limitation, and any and all such variations are considered equivalent and within the scope of the disclosure.

[0123] In a representative embodiment, each ultrasonic transducer controller 265 of the plurality of ultrasonic transducer controllers 265 is implemented as an integrated circuit (“IC”) and is coupled (typically via impedance matching components 212) through corresponding communication lines, wires or bus 220 to the catheter control connector 210, 210A to receive electrical signaling (such as activation or energizing signaling), commands, data (including activation patterns having selections of ultrasonic transducer elements 250), power, and ground from the PIUM 105, for energizing the ultrasonic transducer elements 250of the ultrasonic transducer assembly 205, for transmitting the ultrasonic signals received from the ultrasonic transducer elements 250 of the ultrasonic transducer assembly 205 to the PIUM 105, and for switching or providing power to and signaling from the circumferential array 245 of ultrasonic transducer elements 250. The plurality of ultrasonic transducer controllers 265 are arranged and coupled in parallel with each other, between the catheter control connector 210 and the ultrasonic transducer elements 250. In various representative embodiments, impedance matching components 212 (such as resistors 214 and capacitors 216) may also be included as an option, with the impedance matching components 212 typically electrically coupled between the ultrasonic transducer controllers 265 and the catheter control connector 210, 210A, such as illustrated in FIGs. 7 and 17.

[0124] Viewing or considering the entire plurality of ultrasonic transducer elements250 to be a “set” of ultrasonic transducer elements 250, as discussed in greater detail below, in representative embodiments, the plurality of ultrasonic transducer elements 250 are grouped into subsets 285, physically, electrically, and conceptually. In a representative embodiment, the plurality of ultrasonic transducer elements 250 which are arranged in the circumferential array 245 are further grouped physically and electrically into a plurality of subsets 285 of ultrasonic transducer elements 250, illustrated in FIGs. 8, 12, 16, and 18 as ultrasonic transducer element subset 285i, ultrasonic transducer element subset 2852, ultrasonic transducer element subset 285s. and so on, through ultrasonic transducer element subset 285N. In a representative embodiment, each ultrasonic transducer controller 265, of the plurality of ultrasonic transducer controllers 265, is coupled through corresponding transmit and receive lines, wires or bus 225 to a selected or corresponding subset 285 of the ultrasonic transducer elements 250 of the ultrasonic transducer assembly 205, to selectively and individually address each ultrasonic transducer element 250, or selectively address each pair of ultrasonic transducer elements 250, of the ultrasonic transducer elements 250 of the selected or corresponding subset 285, for example and without limitation, to generate ultrasound transmission and reception of reflected ultrasound signals for image acquisition.

[0125] Each of these ultrasonic transducer element subsets 285 is physically(mechanically and electrically ) coupled (via corresponding separate busses, wires or lines 225i, 2252, 225;. etc., through 225N) to a separate ultrasonic transducer controller 265, illustrated as ultrasonic transducer controller 2651, ultrasonic transducer controller 2652, and so on, through ultrasonic transducer controller 265N. As such, the control and switching of the ultrasonic transducer elements 250 are both electrically and physically (spatially) distributed, using a plurality of individual, separate ultrasonic transducer controllers 265 arranged within the catheter housing 240, 240A, rather than using a single, large integrated circuit having acorresponding large form factor or IC footprint for control and switching. As a result, ultrasonic transducer controller 2651 provides the control and switching of each of the ultrasonic transducer elements 250 of ultrasonic transducer element subset 285 i, ultrasonic transducer controller 2652 provides the control and switching of each of the ultrasonic transducer elements 250 of ultrasonic transducer element subset 2852, and so on, through ultrasonic transducer controller 265N providing the control and switching of each of the ultrasonic transducer elements 250 of ultrasonic transducer element subset 285N, such that the plurality of distributed ultrasonic transducer controllers 265 thereby provide the control and switching of all of the ultrasonic transducer elements 250 of the entire circumferential array 245 of ultrasonic transducer elements 250 (e.g., as shown in FIG. 8 and in FIG. 18).

[0126] This electrical and physical (spatial) distribution of the control and switching of the ultrasonic transducer elements 250, by using a plurality of separate and spaced-apart ultrasonic transducer controllers 265, having comparatively smaller IC sizes (form factors or IC footprints), enables the IVUS catheter 200, 200A to have both a considerably smaller form factor overall and significantly more physical flexibility than prior art IVUS catheters. For example and without limitation, in a representative embodiment, each of the ultrasonic transducer controllers 265 may be configured to have a comparatively long and narrow form factor, and may be distributed and arranged spaced apart radially from each other within the catheter housing 240, 240A (as illustrated in FIG. 13 (and as illustrated in FIG. 17, once the flexible circuit board 460 has been rolled into a cylindrical form)) and / or also optionally longitudinally from each other within the catheter housing 240, 240A (as illustrated as an option in FIG. 18), further enabling the IVUS catheter 200, 200A to have a considerably smaller overall form factor.

[0127] In addition, the plurality of ultrasonic transducer elements 250 are also grouped into a second, conceptual type of subset or set, with these subsets of the plurality of ultrasonic transducer elements 250 referred to herein as “sub-apertures” 275. As mentioned above, all of the ultrasonic transducer elements 250 of the IVUS catheter 200, 200A are not energized and transmitting at the same time, in contrast with the prior art. Instead, an individual ultrasonic transducer element 250 or a pair of ultrasonic transducer elements 250 within the selected subset of the plurality of the ultrasonic transducer elements 250 are energized, within the groups or subsets of ultrasonic transducer elements 250 referred to as sub-apertures 275, as illustrated in FIGs. 12, 16 and 22, either: (1) with each ultrasonic transducer element 250 of any selected sub-aperture 275 individually and separately energized in a selected sequence with a selected delay (z.e., an offset time from the energizing of other ultrasonic transducer elements 250 of the selected sub-aperture 275); or (2) with symmetrical pairs of ultrasonic transducerelements 250 of any selected sub-aperture 275 collectively and simultaneously energized in a selected sequence with a selected delay (i.e., an offset time from the energizing of other ultrasonic transducer elements 250 of the selected sub-aperture 275), for example and without limitation. Generally or typically, other than either the individual ultrasonic transducer element 250 or the symmetrical pair of ultrasonic transducer elements 250 of any selected sub-aperture 275 being energized, all of the other ultrasonic transducer elements 250 of the circumferential array 245 are not energized and remain in an off state or status. This energizing sequence of the ultrasonic transducer elements 250 of the selected sub-aperture 275 with selected energizing delays, creates what may be referred to as corresponding geometric delays in the energizing of the ultrasonic transducer elements 250 of the circumferential array 245 and resulting ultrasound transmission, thereby generating a corresponding ultrasonic wavefront pattern having a selected geometry, such as resulting in a dynamically focused ultrasonic beam 30, as illustrated in FIG. 3.

[0128] In a representative embodiment, the sub-apertures 275 are selected dynamically, for energizing the particular ultrasonic transducer elements 250 within that selected sub-aperture 275. In a representative embodiment, for example and without limitation, sub-apertures 275 may be selected sequentially or in any other order, such as sequentially selecting adjacent ultrasonic transducer elements 250 around the circumferential array 245 to be within any selected sub-aperture 275. For example, a selected first sub-aperture 2751 may include ultrasonic transducer element 250i through ultrasonic transducer element 250s, a selected second sub-aperture 2752 may include ultrasonic transducer element 2502 through ultrasonic transducer element 250 ,. a selected third sub-aperture 275; may include ultrasonic transducer element 2502 through ultrasonic transducer element 25Oio, and so on, as illustrated in FIGs. 12 and 16, and may also be varied by fewer than one ultrasonic transducer element 250 at a time, e.g., in half-element increments, for example and without limitation. By varying which sub-aperture 275 is selected at any given time, a focused ultrasound beam may be generated at any location and any focal point around the IVUS catheter 200, 200A. For example and without limitation, by selecting sub-apertures 275 sequentially around the circumferential array 245, corresponding focused ultrasound beams are generated sequentially around the IVUS catheter 200, 200A, covering 360 degrees. Depending upon the number of ultrasonic transducer elements 250 utilized, the angular resolution may be as small as several degrees, also for example and without limitation. FIG. 22 is a graphical depiction of sub-aperture 275 beamforming showing an example of an 8-element sub-aperture 2751 with a next sub-aperture 2752 advancing a full ultrasonic transducer element 250 (single line density). In practice the sub-aperture 275 can advance in more fine increments for higher line density imaging.

[0129] Within any selected sub-aperture 275, the ultrasonic transducer elements 250 may be energized for transmission (and for receiving reflected ultrasound energy) in any selected activation order or pattern. In a representative embodiment, the activation patterns are predetermined or preset activation patterns. For a selected first sub-aperture 275i, also for example and without limitation, a selected activation (or energizing) pattern may include activating (or energizing) ultrasonic transducer element 250i simultaneously with activating (or energizing) ultrasonic transducer element 2508, followed by (with a first predetermined delay) activating (or energizing) ultrasonic transducer element 2502simultaneously with activating (or energizing) ultrasonic transducer element 2507, followed by (with a second predetermined delay) activating (or energizing) ultrasonic transducer element 2503simultaneously with activating (or energizing) ultrasonic transducer element 250g, followed by (with a third predetermined delay) activating (or energizing) ultrasonic transducer element 2504simultaneously with activating (or energizing) ultrasonic transducer element 2505. For a selected second sub-aperture 2752, such as illustrated in FIG. 22, also for example and without limitation, a selected activation (or energizing) pattern may include activating (or energizing) ultrasonic transducer element 2502simultaneously with activating (or energizing) ultrasonic transducer element 250 ,. followed by (with a first predetermined delay) activating (or energizing) ultrasonic transducer element 2503simultaneously with activating (or energizing) ultrasonic transducer element 2508, followed by (with a second predetermined delay) activating (or energizing) ultrasonic transducer element 2504simultaneously with activating (or energizing) ultrasonic transducer element 2507, followed by (with a third predetermined delay) activating (or energizing) ultrasonic transducer element 25 O5 simultaneously with activating (or energizing) ultrasonic transducer element 250g.

[0130] Those having skill in the art will recognize that selection or creation of any given activation pattern will provide a resulting ultrasound beam geometry and scan lines, which may be varied or selected according to any clinical, interventional, imaging, or image processing need, for example and without limitation. In addition, a wide variety of activation patterns are within the scope of the disclosure, including acquiring scan lines in a more distributed way around the circumferential array 245 of ultrasonic transducer elements 250, e.g., sequentially selecting ultrasonic transducer element 250i, ultrasonic transducer element 25016, ultrasonic transducer element 250332, ultrasonic transducer element 25043, ultrasonic transducer element 2502, ultrasonic transducer element 250I7, ultrasonic transducer element 25033, ultrasonic transducer element 25046, and so on, such as to reduce a “stitching artifact”, also for example and without limitation. Any and all such energizing sequences and activation patterns are withing the scope of the disclosure, in addition to those specific examples.

[0131] In a representative embodiment, each predetermined activation pattern, of a plurality of predetermined activation patterns, comprises: (1) a selection of ultrasonic transducer elements 250 for activation, from the plurality of ultrasonic transducer elements 250;(2) an ordering of the selected ultrasonic transducer elements 250 for activation, such as described above; and (3) a plurality of predetermined time delays for sequential activation of the ordered, selected ultrasonic transducer elements 250, such as the first, second, and third time delays described above. As discussed in greater detail below, in a first representative embodiment, a first portion of the predetermined activation patterns, namely, the selection of ultrasonic transducer elements 250 for activation, from the plurality of ultrasonic transducer elements 250) ((1) above), are stored in the activation pattern registers (memory) 305 of each of the ultrasonic transducer controllers 265, with the remaining second and third portions ((2) and(3), the ordering and time delays for sequential activation) are stored in the memory circuit 185 of the IVUS (host) console 150 and / or the memory circuit 190 of the PIUM 105, equivalently. It should be noted that these selections of ultrasonic transducer elements 250 for activation may be different for each ultrasonic transducer controller 265, and also may differ depending upon the sub-aperture 275 selection and any overlap of the sub-aperture 275 selection across the ultrasonic transducer elements 250 controlled and activated by different ultrasonic transducer controllers 265.

[0132] In a second, alternative representative embodiment within the scope of the disclosure, the entirety of each predetermined activation pattern ((1) the selection of ultrasonic transducer elements 250 for activation, from the plurality of ultrasonic transducer elements 250, and (2) and (3), the ordering and time delays for sequential activation) are stored in the activation pattern registers (memory) 305 of each of the ultrasonic transducer controllers 265, with the selection, ordering, and time delays for energizing of the ultrasonic transducer elements 250 largely controlled directly by the ultrasonic transducer controllers 265. Those having skill in the art will recognize that there are a wide variety of ways and locations to store one or more portions of the activations patterns, and any and all such variations are also considered equivalent and within the scope of the disclosure.

[0133] A first way to control the activation (or energizing) of the ultrasonic transducer elements 250 would be to have direct wiring to each ultrasonic transducer element 250 with wires running along the length of the IVUS catheter 200, 200A, terminating in an appropriate catheter control connector 210, 210A. The connector is then connected to the PIUM 105 and IVUS console 150. The IVUS console 150 controls the transmit and receive event sequence to advance the sub-aperture 275 around the circumference of the IVUS catheter 200, 200A. The IVUS console 150 may also calculate the transmit and receive beam delays. This allows formultiple -focus imaging as well as arbitrary scanline placement. An image is then created with the individual scanlines. A second and considerably more efficient way to control the activation (or energizing) of the ultrasonic transducer elements 250 is described in greater detail below with reference to FIGs. 12, 16, and 19 - 26.

[0134] It should be noted that as any given sub-aperture 275 is selected around the circumferential array 245, the ultrasonic transducer elements 250 which are to be energized may be from different ultrasonic transducer element subsets 285 and further may be coupled to different ultrasonic transducer controllers 265. Continuing with the example above for the selected second sub-aperture 2752, also for example and without limitation, the ultrasonic transducer element 2502may be part of ultrasonic transducer element subset 2851 coupled to ultrasonic transducer controller 2651 while ultrasonic transducer element 250.. may be part of ultrasonic transducer element subset 2852and coupled to ultrasonic transducer controller 2652, for example and without limitation. In a representative embodiment, also for example and without limitation, depending upon the number of ultrasonic transducer elements 250 being selected for a given sub-aperture 275, ultrasonic transducer elements 250 being energized may be from one or two different (but typically adjacent) ultrasonic transducer element subsets 285, depending upon the selected activation pattern.

[0135] Referring to FIGs. 19 and 20, a representative embodiment of an ultrasonic transducer controller 265 comprises a controller communication interface circuit 300, one or more activation pattern registers (or memory) 305, an activation pattern selection logic circuit 310, a switch decoder circuit 315, one or more voltage translator circuit(s) 320, and a crosspoint switch matrix circuit 325. Not separately illustrated, the ultrasonic transducer controller 265 may also include a power-on-reset circuit and a clock or clocking circuit, for example and without limitation, along with other optional components discussed below, depending upon the selected embodiment. In a representative embodiment, the crosspoint switch matrix circuit 325 comprises an array of analog switches 355, typically implemented as high voltage transmission gates (having a PMOS device in parallel with an NMOS device, not separately illustrated), with each analog switch 355 coupled to a first input / output pad 335 (illustrated as first input / output pads 3351 through 3354) and a second input / output pad 330, with each second input / output pad 330 coupled (via a line 225 and corresponding conductive pad 225 A) to a single ultrasonic transducer element 250. The first input / output pads 335 receive (from the PIUM 105 or the IVUS console 150 via the PIUM 105), via wires, lines or bus 340 (as part of lines, wires or bus 220 or 222), an input voltage (e.g., typically either -9V or +9V, for example and without limitation) for energizing selected ultrasonic transducer elements 250, and output or otherwise provide a received signal (received from an ultrasonic transducerelement 250 from a reflected ultrasound wave) to the PIUM 105 and / or the IVUS console 150 via the PIUM 105 for received ultrasound signal processing. Each of the second input / output pads 330 transmit, via lines, wires or bus 225, the selected, switched input voltage (e.g., typically either -9V or +9V, for example and without limitation) to energize a single ultrasonic transducer element 250, and provide a received signal (received from an ultrasonic transducer element 250 from a reflected ultrasound wave) through a selected analog switch 355 to a first input / output pad 335 for output to the PIUM 105 and / or the IVUS console 150 via the PIUM 105 for received ultrasound signal processing.

[0136] In addition, depending upon the selected embodiment, an ultrasonic transducer controller 265 may also include an activation signal generator and additional control logic gates (not separately illustrated). This would be utilized for embodiments in which the ultrasonic transducer controllers 265 store the entire activation patterns ((1), (2), and (3) discussed above), and each of the ultrasonic transducer controllers 265 will generate an activation signal, which it will switch or transmit to the selected ultrasonic transducer elements 250 for activation with the appropriate ordering and time delays.

[0137] The controller communication interface 300 receives signaling data (via lines, wires or bus 345 (as part of lines, wires or bus 220, 222)), such as pointers and commands, from the PIUM 105 and / or from the IVUS console 150 via the PIUM 105. In a representative embodiment, the controller communication interface 300 is configured, adapted or otherwise structured to implement a Serial Peripheral Interface (“SPI”) protocol, for example and without limitation. Also in a representative embodiment, the controller communication interface 300 receives portions of a plurality of predetermined or preset activation (or energizing) patterns (as mentioned above), which are stored in the activation pattern registers (or memory) 305, and which may be called or read sequentially or in any other selected order using an SPI command, also for example and without limitation. As discussed above, the predetermined or preset activation (or energizing) patterns stored in the activation pattern registers (or memory) 305 provide for the selection of the individual ultrasonic transducer elements 250 or pairs of individual ultrasonic transducer elements 250 for activation (or energizing) for transmission of ultrasound signals and for reception of return ultrasound signals, for example and without limitation.

[0138] For activating (or energizing) the ultrasonic transducer elements 250, an activation (or energizing) pattern is selected from the activation pattern registers (or memory) 305, using activation pattern selection logic circuit 310, which may be implemented using various logic gates, state machines, and / or multiplexers, for example and without limitation, and is provided to the switch decoder circuit 315. Which ultrasonic transducer controller 265 isselected, and which activation (or energizing) pattern is selected from the activation pattern registers (or memory) 305 of the selected ultrasonic transducer controller 265, is generally determined by: (1) an address of the ultrasonic transducer controller 265, and (2) a register or memory pointer, both transmitted from or otherwise provided by the PIUM 105 and / or from the IVUS console 150 via the PIUM 105. The switch decoder circuit 315, which may be implemented using various logic gates and state machines, also for example and without limitation, is configured or adapted to determine, from the selected activation (or energizing) pattern, which analog switches 355 are to be turned on (and conducting), to implement the selected activation (or energizing) pattern. The switch 355 selection from the switch decoder circuit 315 is then provided to the voltage translator circuit 320, which converts the (typically lower voltage signal from the switch decoder circuit 315) to a higher voltage level to operate and turn on the selected analog switches 355 of the crosspoint switch matrix circuit 325 (e.g., implemented as transmission gates which may require comparatively higher voltage levels to operate), and thereby activate (or energize) the corresponding ultrasonic transducer elements 250.

[0139] As mentioned above, a plurality of ultrasonic transducer controllers 265 are utilized and distributed within the IVUS catheter 200, 200A. Each ultrasonic transducer controller 265 is individually addressable, such as by using a plurality of addressing lines (via lines, wires or bus 345 (as part of lines, wires or bus 220, 222)) with address selection or signaling provided from the PIUM 105 and / or from the IVUS console 150 via the PIUM 105. In a representative embodiment, for example and without limitation, each ultrasonic transducer controller 265 includes three address pins (not separately illustrated), each of which is tied to either a predetermined voltage level (VDD, e.g., 1.8 V) or ground (VSS), providing up to eight unique addresses. Using this addressing to each ultrasonic transducer controller 265, any subaperture 275 may be selected, and any activation (or energizing) pattern may be selected for that selected sub-aperture 275 for the ultrasonic transducer elements 250 coupled to the selected ultrasonic transducer controller 265.

[0140] In a representative embodiment, the communication lines, wires or bus 220 may be shielded, such as implemented as one or more coaxial cables. With six ultrasonic transducer controllers 265 utilized and distributed in parallel within the IVUS catheter 200, 200A in a representative embodiment, for example and without limitation, a total of between twelve to twenty communication lines or wires 220 are utilized, such as four or fewer (or four or more) communication lines or wires 220 being utilized for supply voltages (e.g., digital power, digital ground, high voltages (e.g., +9 V and -9 V), a drain line connected to cable shielding), four or fewer (or four or more) shielded communication lines or wires 220 utilizedfor analog transmit and receive inputs, and four or fewer (or four or more) communication lines or wires 220 utilized for digital logic for SPI communication, such as for commands and pointers.

[0141] As indicated above, in a representative embodiment, the activation (or energizing) of the ultrasonic transducer elements 250 is controlled utilizing the plurality of ultrasonic transducer controllers 265 arranged (generally spaced apart and toward the distal end 207) within the IVUS catheter 200, 200A. The plurality of ultrasonic transducer controllers 265 with the crosspoint switch matrix circuits 325 allow for the dynamic assignment of active sub-apertures 275 and can be pre-programed or controlled in real time by a connected IVUS console 150 and / or the PIUM 105. The stored and selected activation (or energizing) patterns (stored in the activation pattern registers (or memory) 305 and in the memory circuit 185 of the IVUS console 150 and / or the memory circuit 190 of the PIUM 105) controls the transmit and receive event sequence to advance the sub-aperture 275 around the circumference of the array 245 of ultrasonic transducer elements 250 of the IVUS catheter 200, 200A. The stored and selected activation (or energizing) patterns (stored in the activation pattern registers (or memory) 305 and in the memory circuit 185 of the IVUS console 150 and / or the memory circuit 190 of the PIUM 105) also includes the transmit beam delays, which also allows for multiple -focus imaging as well as arbitrary scanline placement, and an image is also then created with the individual scanlines. These ultrasonic transducer controllers 265 with the crosspoint switch matrix circuits 325 allow the same sub-aperture 275 flexibility described above, but with a significant reduction in the number of control wires running the length of IVUS catheter 200, 200A.

[0142] The ultrasound signals from the ultrasonic transducer elements 250 are beamformed using geometric focus delay calculations and individual scanlines are produced from each transmit / receive sequence. In a representative embodiment, the received scanlines are pre-processed in the PIUM 105 and then sent to IVUS console 150 for complete signal and image processing. This includes bandpass filtering, demodulation, log compression and scan conversion, for example and without limitation.

[0143] To provide a comparatively low-cost, manufacturable and high performance disposable IVUS catheter 200, 200A, a plurality of ultrasonic transducer controllers 265 with the crosspoint switch matrices 325 are utilized to allow flexible control of a large number of ultrasonic transducer elements 250 but requiring a comparatively minimum number of wires running the length of the IVUS catheter 200, 200A. In this application, the IVUS catheter 200, 200A imaging components (the circumferential array 245 of ultrasonic transducer elements 250) should be round and have a comparatively small diameter (e.g., 4 - 12 Fr (1.33 - 4 mm)(with 1 Fr = 0.33 mm diameter or, equivalently, 3 Fr = 1 mm diameter or 1 Fr = 3 x (diameter in mm)). To achieve this comparatively small size, a plurality of ultrasonic transducer controllers 265 with the crosspoint switch matrices 325 are utilized, each of which is comparatively narrow and small, and which are ganged together as illustrated to coordinate with each other and control the ultrasonic transducer elements 250, instead of using a single large and rigid IC that controls all of the ultrasonic transducer elements 250. As mentioned above, each individual ultrasonic transducer controller 265 is connected to a subset (or set) 285 of the total number of ultrasonic transducer elements 250, and each ultrasonic transducer controller 265 can be controlled via a digital communication protocol (e.g., SPI). This inventive, distributed design allows the number of wires used to be significantly decreased from wire pairs equal to the number of ultrasound elements (wired approach), and instead requiring only the digital communications lines, the power supply lines and ultrasound signal lines equal to the largest active sub-aperture 275 used, such as described above. Alternatively, if symmetric sub-apertures 275 can be used, the number of ultrasound signal lines can be half of the largest sub-aperture 275 and signals to and from the ultrasonic transducer elements 250 can be directed from a single line to the symmetric pairs of ultrasonic transducer elements 250.

[0144] FIG. 21 illustrates a representative method 500 for controlling the switching and energizing of the representative circumferential ultrasonic transducer array 245 for dynamic beamforming and ultrasound signal reception from the representative circumferential ultrasonic transducer array 245, and also provides a useful summary. Referring to FIG. 21, for this representative embodiment, the method 500 begins, start step 505, with the portions of the activation patterns comprising the selections of ultrasonic transducer elements 250 for activation, from the plurality of ultrasonic transducer elements 250, for a plurality of corresponding, selected sub-apertures 275, having been pre-loaded and stored in the activation pattern registers (or memory) 305 of the various ultrasonic transducer controllers 265. In other embodiments, as mentioned above, the relevant, complete activation patterns may be stored in the activation pattern registers (or memory) 305 of the various ultrasonic transducer controllers 265. For this representative embodiment, the IVUS console 150 (and / or PIUM 105) generates the activation or energizing signals and further controls the activation timing and energizing time delays for the selected activation pattern of corresponding ultrasonic transducer elements 250 for a selected sub-aperture 275. The IVUS console 150 (and / or PIUM 105) selects a first (or next) activation pattern (e.g., from memory circuit 185 of the IVUS console 150 or from the memory circuit 190 of the PIUM 105), step 510, and transmits corresponding digital information or other data to the selected one or more ultrasonic transducer controllers 265, step 515, typically transmitting the address(es) of the selected one or more ultrasonic transducercontrollers 265 and a pointer (or memory pointer) to the address or location in the activation pattern registers (or memory) 305 storing the relevant portion of the selected activation pattern, e.g., the selections of ultrasonic transducer elements 250 for activation for the first or next selected sub-aperture 275.

[0145] Following receipt of the corresponding command from the IVUS console 150(and / or PIUM 105), the selected, addressed ultrasonic transducer controller(s) 265 (using the controller communication interface 300, the activation pattern selection logic circuit 310, the switch decoder circuit 315, and the voltage translator circuit 320) then turns on all of the analog switches 355 (of the crosspoint switch matrix 325) which correspond to the selections of ultrasonic transducer elements 250 for activation for the first or next selected sub-aperture 275 of the selected activation pattern, step 520, i.e., places all of the analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the first or next selected sub-aperture 275 in an on or conducting state, such that each selected analog switch 355 will pass energizing pulses (received on a selected first input / output pad 335) to the corresponding ultrasonic transducer elements 250 (via a connected second input / output pad 330) and will subsequently pass any ultrasonic signals received from the corresponding ultrasonic transducer elements 250 back to the IVUS console 150 (and / or PIUM 105). The IVUS console 150 (via the PIUM 105) and / or the PIUM 105 then transmits a first energizing pulse or pulses (via lines or wires 220, 222 and pads 335) to the first selected ultrasonic transducer elements 250, typically to a selected first pair of ultrasonic transducer elements 250 (or to a first individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275, step 525. More particularly, in step 525, the IVUS console 150 (via the PIUM 105) and / or the PIUM 105 transmits a first energizing pulse or pulses (via lines or wires 220, 222) to a selected first input / output pad 335, such as to first input / output pad 3351, which has been connected via selected analog switches 355 (which have already been placed in an on and conducting state, corresponding to the activation pattern) to selected second input / output pads 330 which are correspondingly coupled to the first selected ultrasonic transducer elements 250, typically a selected first pair of ultrasonic transducer elements 250 (or to an individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275, such as coupled to ultrasonic transducer element 2500and ultrasonic transducer element 250?. for example and without limitation.

[0146] Following a first or next predetermined time delay, the IVUS console 150 (via the PIUM 105), and / or the PIUM 105 then transmits a second or next energizing pulse or pulses (via lines or wires 220, 222 and pads 335) to the second or next selected ultrasonic transducer elements 250, typically to the second or next selected pair of ultrasonic transducer elements 250(or to an individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275, step 530. More particularly, in step 530, the IVUS console 150 (via the PIUM 105) and / or the PIUM 105 transmits a second or next energizing pulse or pulses (via lines or wires 220, 222) to a selected first input / output pad 335, such as to first input / output pad 3352, which has been connected via selected analog switches 355 (which have already been placed in an on and conducting state, corresponding to the activation pattern) to selected second input / output pads 330 which are correspondingly coupled to the second or next selected ultrasonic transducer elements 250, such as to the second or next selected pair of ultrasonic transducer elements 250 (or to an individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275, such as coupled to ultrasonic transducer element 250i and ultrasonic transducer element 250e, for example and without limitation.

[0147] When there are additional ultrasonic transducer elements 250 to be energized or activated for the selected sub-aperture 275, step 535, the method iterates, returning to step 530, such that following a second or next predetermined time delay, the IVUS console 150 (via the PIUM 105) and / or the PIUM 105 then transmits next energizing pulses (via lines or wires 220, 222 and pads 335) to the next selected ultrasonic transducer elements 250, such as to the selected next pair of ultrasonic transducer elements 250 (or to an individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275. More particularly, in additional iterations of step 530, following a second or next predetermined time delay, the IVUS console 150 (via the PIUM 105) and / or the PIUM 105 transmits a next energizing pulse or pulses (via lines or wires 220, 222) to a selected first input / output pad 335, such as to first input / output pad 335s. which has been connected via selected analog switches 355 (which have already been placed in an on and conducting state, corresponding to the activation pattern) to selected second input / output pads 330 which are correspondingly coupled to the next selected ultrasonic transducer elements 250, such as to the next selected pair of ultrasonic transducer elements 250 (or to an individual ultrasonic transducer element 250) of the first or next selected sub-aperture 275, such as coupled to ultrasonic transducer element 2502and ultrasonic transducer element 2505, for example and without limitation. Also in additional iterations of step 530, following a third or next predetermined time delay, the IVUS console 150 (via the PIUM 105) and / or the PIUM 105 transmits a next energizing pulse or pulses (via lines or wires 220, 222) to a selected first input / output pad 335, such as to first input / output pad 3354, which has been connected via selected analog switches 355 (which have already been placed in an on and conducting state, corresponding to the activation pattern) to selected second input / output pads 330 which are correspondingly coupled to the next selected ultrasonic transducer elements 250, such as to the next selected pair of ultrasonic transducer elements 250 (or to an individualultrasonic transducer element 250) of the first or next selected sub-aperture 275, such as coupled to ultrasonic transducer element 250; and ultrasonic transducer element 2504, for example and without limitation. Such an energizing sequence and ordering with corresponding time delays would generate a focused ultrasonic beam 30, having a scan line center and focal point such as illustrated in an discussed below with reference to FIG. 23.

[0148] When there are no additional ultrasonic transducer elements 250 to be energized or activated for the selected sub-aperture 275 in step 535, the corresponding ultrasonic transducer controller(s) 265 continue to maintain all of the switches of the selected sub-aperture 275 in an on state while any ultrasonic (ultrasound) signals are being received by the corresponding ultrasonic transducer elements 250 of the selected sub-aperture 275 and are being transmitted back to the IVUS console 150 (via the PIUM 105) and / or the PIUM 105, step 540.

[0149] Following reception of the ultrasonic signals, the IVUS console 150 (via thePIUM 105) and / or the PIUM 105 will then generate and transmit one or more corresponding commands to the selected ultrasonic transducer controller(s) 265, for turning off either all of or one or more of the analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the first or next selected sub-aperture 275, step 545. In a first selected embodiment, the command generated by the IVUS console 150 (via the PIUM 105) and / or the PIUM will turn off all of the analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the first or next selected sub-aperture 275. In a second selected embodiment, the command generated by the IVUS console 150 (via the PIUM 105) and / or the PIUM will turn off only some of the analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the first or next selected sub-aperture 275 and will maintain in an on state those analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the next selected sub-aperture 275, for example and without limitation.

[0150] Following receipt of the corresponding command from the IVUS console 150(and / or PIUM 105) in step 545, some or all of the analog switches 355 corresponding to the selected ultrasonic transducer elements 250 of the first or next selected sub-aperture 275 are then turned off (into an off, nonconducting state) by the ultrasonic transducer controller(s) 265 (using the controller communication interface 300, the activation pattern selection logic circuit 310, the switch decoder circuit 315, and the voltage translator circuit 320), step 550. When there are any ultrasonic transducer elements 250 of any additional sub-apertures 275 remaining to be energized, step 555, the method iterates, returning to step 510 to select the next activation pattern for energizing of the ultrasonic transducer elements 250. When there are no ultrasonictransducer elements 250 of any additional sub-apertures 275 remaining to be energized, step 555, the method may end, return step 560.

[0151] For this representative embodiment, the method of energizing the corresponding ultrasonic transducer elements 250 and receiving reflected ultrasound signals from the corresponding ultrasonic transducer elements 250 may be considered to have separate digital and analog phases. The digital phases consist of the selection and switching on or off of the analog switches 355 (steps 510, 515, 520, 545, and 550) which are coupled to the selected ultrasonic transducer elements 250 via corresponding second input / output pads 330. The separate analog phase consists of the transmission of the energizing pulses to the corresponding ultrasonic transducer elements 250 of the selected sub-aperture 275, with the selected time delays, via selected first input / output pads 335 and the selected, on and conducting analog switches 355, and the reception of the reflected ultrasonic (or ultrasound) signals by the corresponding ultrasonic transducer elements 250 and transmission of the received ultrasonic signals back to the IVUS console 150 (via the PIUM 105) and / or to the PIUM 105 (steps 525, 530, 535, and 540). In the analog phase, while the energizing pulses are being transmitted to the corresponding ultrasonic transducer elements 250 of the selected sub-aperture 275 and while ultrasound signals are being received by the corresponding ultrasonic transducer elements 250 of the selected sub-aperture 275, no digital switching is occurring. As a result, the ultrasonic transducer controller(s) 265 is quiescent during the analog phase, and therefore does not generate any digital noise which might potentially interfere with either the transmitted energizing pulses or the received ultrasound signals, providing a significantly greater signal-to- noise ratio than prior art devices.

[0152] As mentioned above, in a second, alternative representative embodiment within the scope of the disclosure, as mentioned above, the entirety of each of the predetermined activation patterns ((1) a selection of ultrasonic transducer elements 250 for activation, from the plurality of ultrasonic transducer elements 250; (2) an ordering of the selected ultrasonic transducer elements 250 for activation; and (3) a plurality of predetermined time delays for sequential activation of the ordered, selected ultrasonic transducer elements 250, such as the first, second, and third time delays described above) are stored in the activation pattern registers (memory) 305 of each of the ultrasonic transducer controllers 265, with the selection, ordering, and time delays for energizing of the ultrasonic transducer elements 250 largely controlled directly by the ultrasonic transducer controllers 265, typically in synchronization with the IVUS console 150 (via the PIUM 105) and / or the PIUM. For example and without limitation, the IVUS console 150 (via the PIUM 105) and / or the PIUM may generate one or more commands to begin the ultrasound transmission along with a series of energizing pulses, which are thenrouted through the switching of the analog switches 355 of the crosspoint switch matrix 325 to the selected ultrasonic transducer elements 250 of any given or selected sub-aperture 275 and according to the appropriate ordering and appropriate time delays by and under the control of the corresponding ultrasonic transducer controller 265.

[0153] In another alternative representative embodiment within the scope of the disclosure, as mentioned above, an ultrasonic transducer controller 265 may also include an activation signal generator and additional control logic gates. In addition to the ultrasonic transducer controllers 265 storing the entire activation patterns ((1), (2), and (3) discussed above), each of the ultrasonic transducer controllers 265 also will generate an activation signal, which it will switch (using analog switches 355) or transmit to the selected ultrasonic transducer elements 250 for activation with the appropriate ordering and time delays. In another alternative representative embodiment within the scope of the disclosure, control of the energizing of the ultrasonic transducer elements 250 may be divided in other ways between the ultrasonic transducer controllers 265, on the one hand, and the IVUS console 150 (via the PIUM 105) and / or the PIUM 105, on the other hand. Any and all such variations are considered equivalent and within the scope of the disclosure.

[0154] FIG. 23 is a cross-sectional view (through the A - A’ plane of FIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array 245 of ultrasonic transducer elements 250 and a partially exploded view illustrating focal delays with a scan line center 405 and focal point 410 for a selected nonelement 250 centered sub-aperture 275A for a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein. FIG. 24 is a cross-sectional view (through the A - A’ plane of FIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG.15) illustrating a representative circumferential array 245 of ultrasonic transducer elements 250 and a partially exploded view illustrating focal delays with a scan line center 415 and focal point 420 for a selected element-centered sub-aperture 275B for a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein. As mentioned above, the representative embodiments include the ability to dynamically control individual ultrasonic transducer elements 250 of the circumferential array 245 to create a focused ultrasound wave. The focal points 410, 420 can be dynamically altered to maximize image resolution across a larger depth of field and at arbitrary scanline spacing.

[0155] On transmit, a sub-aperture 275 set of ultrasonic transducer elements 250 are pulsed with pre -calculated geometric focal delays, which allows control of the point of maximum focus, with example sub-apertures 275 illustrated in FIGs. 23 and 24. As illustrated in FIG. 23, the sub-aperture 275 is centered between ultrasonic transducer elements 250 in asub-aperture 275 having an even number of elements. As illustrated in FIG. 24, the subaperture 275 is centered on an ultrasonic transducer element 250 in a sub-aperture 275 having an odd number of elements.

[0156] FIG. 25 is a cross-sectional view (through the A - A’ plane of FIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array 245 of ultrasonic transducer elements 250 and a partially exploded view illustrating a focus delay calculation for a dynamically selectable focal point for a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein. Referring to FIG. 25, any selected ultrasonic transducer element 250 of the circumferential array 245 may be considered to have a position (r, 0), where “r” is the radial distance from the longitudinal axis 85 of the IVUS catheter 200, 200A and “0” is the angle from the scan line center 405 (or 415), as illustrated. Typically, “r” will be the same for each ultrasonic transducer element 250 and the angle 0 will vary within each sub-aperture 275 for any given scan line center 405, 415. In addition, there will be a predetermined or dynamically adjustable focal distance 445, also determined or measured from the longitudinal axis 85 of the IVUS catheter 200, 200A. Using the element 250 position (r, 0), right triangles 425, 435 may be defined, with right triangle 425 having sides dl, d2, and with a hypotenuse of length “r”, and right triangle 435 having sides d2, d3, and with a hypotenuse of length “p”, also referred to as the element focal delay distance, as illustrated. The focus delay calculation is as follows:1. The position of an ultrasound element i on the IVUS catheter 200, 200A is given by (r, 0).2. The calculation of the lengths dl and d2 are: dl = r * cos 6,' and dl = r * sin 6.3. The focal point 410 is given by coordinates (0, Focal Distance 445).4. The distance d3 is then given as d3 = Focal Distance - dl .5. The distance “p” from an ultrasound element 250 i to the focal point 410 is then: Distance “p” = d32+ d22, and is calculated for each element 250 in the active subaperture 275.6. The focus delay for each element 250 i is calculated as:„ , max(Distance)' "p"-Distance"p"(i . . .Delay( i) = - Speedo Sound - ’w™t lc max(Distance) p referring to the distance “p” from the outermost ultrasound element 250 of the active sub-aperture 275 to the focal point 410.This results in the transmit delays being zero on the outer-most elements 250 (i.e., thoseelements furthest from the scan line center 405, 415) and maximum in the center of the active sub-aperture 275 (i.e., a maximum delay for those elements closest to the scan line center 405, 415), such as described in the various examples discussed above.

[0157] Figure (or “FIG.”) 26 is a cross-sectional view (through the A - A’ plane ofFIG. 9A) and is a cross-sectional view (through the E - E’ plane of FIG. 15) illustrating a representative circumferential array 245 of ultrasonic transducer elements 250 and a partially exploded view illustrating a plurality of dynamically selectable focal points 430, 440 for a representative embodiment of an IVUS catheter 200, 200A in accordance with the disclosure herein. A particular scanline has optimal resolution in the region around the transmit focal point 430, 440. Because the system 100, 100A with the IVUS catheter 200, 200A, respectively, can focus the transmit event at an arbitrary distance, the “depth of field” is improved using multiple transmit / receive events. Each of these events will have a different transmit focal point 430, 440, with two transmit focal points 430, 440 illustrated in FIG. 26. The scanline will be constructed after the two successive transmit / receive events are complete, with focal point 430 transmit / receive used for the first portion of the constructed scanline 450, and with focal point 440 used for the second portion of the constructed scanline 450. The two acquisitions may be blended and transitioned in a region between the two focal points 430, 440.

[0158] FIG. 27 is a flow chart illustrating a method of dynamic beamforming with intravascular imaging using an IVUS catheter 200, 200A in accordance with the disclosure herein, and provides a useful summary. Typical use cases for this imaging system 100, 100A and capability of the IVUS catheter 200, 200A are to record multiple, successive frames as the IVUS catheter 200, 200A is “pulled back” through the vascular anatomy. These “pullbacks” generally start at some distal anatomical landmark, such as the hepatic veins in the inferior vena cava and progress proximally down through and past the area of interest. During pullback, all of the frames are recorded for later quantification and review.

[0159] Referring to FIG. 27, the method 600 begins, start step 605, with using theIVUS console 150 to determine or select one or more activation or energizing patterns for ultrasonic transducer elements 250 having selected focal point(s) and scan line(s) for use in a human or veterinary subject, such as selecting the one or more activation patterns from the memory circuit 185, and loading the one or more activation or energizing pattem(s) into an IVUS catheter 200, 200A, step 610. In a representative embodiment, a sub-aperture 275 of circumferential array 245 of ultrasonic transducer elements 250 is selected, step 615. In another representative embodiment, the sub-aperture selection is part of the activation or energizing pattern determined or selected in step 610. Medical personnel then insert and position the IVUS catheter 200, 200A at a first selected or desired vasculature location in asubject, step 620. The ultrasonic transducer elements 250 are then activated (energized) according to the selected activation or energizing pattern, step 625, and signals from reflected ultrasound waves are received by the IVUS catheter 200, 200A and transmitted for signal processing to the IVUS console 150 (typically via the PIUM 105), step 630. When additional images are to be obtained, step 635, the IVUS catheter 200, 200A is pulled to a second or next selected or desired vasculature location, step 640, and the method iterates, returning to step 625. When no further additional images are to be obtained in step 635, the IVUS catheter 200, 200A is removed from the subject, step 645, and the method may end, return step 650.

[0160] Individual IVUS catheter 200, 200A images and IVUS catheter 200, 200A pullbacks are used in multiple ways. They are used to look at vessel size and shape as well as vascular wall thickness and composition. Images are also used to look for pathology such as the presence of thrombus or some sort of physical compression from external sources. Images within one vessel are used to confirm position within the anatomy by looking at the surrounding, associated vessels. An example would be to see an associated artery adjacent to the vein to confirm that the IVUS catheter 200, 200A is in the correct vein and not a collateral vein, for example and without limitation.

[0161] As mentioned above, various representative embodiments provide apparatuses, methods and systems specifically designed for the IVUS catheter 200, 200A, such as apparatuses, methods and systems for solid state intravascular ultrasound catheterization that enables not only use of modem ultrasound imaging techniques, but also enables high spatial and temporal resolution imaging with greater dynamic range and more flexible imaging modes. Representative embodiments provide dynamic and user-selectable (and / or user-programmable) focusing of the ultrasonic beam, including lateral control of the transmitted ultrasonic energy and control of the intensity of the sonification pattern. The representative embodiments of an IVUS catheter 200, 200A also have a comparatively small form factor with a comparatively reduced diameter, and further have sufficient flexibility for access to desired locations with the vasculature, such as insertion into and around sharp bends in vessels, among other features.

[0162] The representative embodiments further provide arbitrary transmit focusing, using selectable, active sub-apertures and selectable delay profiles. The representative embodiments include the capability to use multiple transmit foci to create a single composite scanline with a greater focus depth of field. In addition, real time receive sub-apertures provide for individual scanlines in a single transmit / receive event, increasing the imaging frame rate, providing improved signal-to-noise ratios (SNR) and improved dynamic ranges for greater image penetration depth.

[0163] The representative embodiments further provide arbitrary scanline positioning, which further enables creating high density scanlines for improved lateral resolution and far- field resolution. This also serves to reduce the geometric impact of beam spreading in a very tightly-curved array. The representative embodiments further provide an IVUS system 100, 100A that enables both geometric delay beamforming as well as synthetic reconstruction. The representative embodiments further provide the capability to electronically steer the ultrasonic transmit / receive sequence, to enable imaging modes such as phased array imaging or spatial compounding, for example and without limitation.

[0164] As mentioned above, the representative embodiments of the IVUS catheter200, 200A may have any size (height, width, depth), shape, or form factor suitable for use with intravenous insertion in a human or veterinary subject, and all such variations are considered equivalent and within the scope of the disclosure. In addition, the representative embodiments illustrate different combinations of features and elements, with any and all mixing and matching of any of the various features and elements and any and all combinations of any of the various features and elements are within the scope hereof.

[0165] The IVUS catheter 200, 200A and other components may be fabricated in a wide variety of ways, including integrally formed (e.g., injection molded, 3D printed) or assembled from separate components (e.g., using any suitable fasteners or adhesives, not separately illustrated), and all such variations are considered equivalent and within the scope of the disclosure. The IVUS catheter 200, 200A and other components may be implemented using any suitable material, and may be opaque or transparent, with suitable materials including any rigid (or semi-flexible) polymer or plastic, such as polyvinylchloride (PVC), polystyrene, polyacrylate, polytetrafluoroethylene (PTFE or Teflon), nylon, polycarbonates, polyesters, carbon fiber, glass, silicone, silicone rubber, a metal, an alloy, etc., for example and without limitation, and all such variations are considered equivalent and within the scope of the disclosure. The IVUS catheter 200, 200A also may have one or more coatings (not separately illustrated), such as an antibiotic or antimicrobial coating, a hydrophilic coating, for example and without limitation.

[0166] Representative examples of suitable polymers include, but are not limited to, fluorinated polymers or copolymers such as poly(vinylidene fluoride), poly( vinylidene fluoride-co-hexafluoropropene), poly(tetrafluoroethylene), and expanded polytetrafluoroethylene); poly (sulfone); poly(N-vinyl pyrrolidone); poly( aminocarbonates); poly(iminocarbonates); poly(anhydride-co-imides), poly(hydroxyvalerate); poly(U-lactic acid); poly(U-lactide); poly(caprolactones); poly(lactide-co-glycolide ); poly (hydroxybutyrates ); poly(hydroxybutyrate-co-valerate); poly(dioxanones); poly(orthoesters); poly(anhydrides);poly(glycolic acid); poly (glycolide); poly(D,L-lactic acid); poly(D,L-lactide); poly(glycolic acid-cotrimethylene carbonate); poly(phosphoesters); poly(phosphoester urethane); poly(trimethylene carbonate); poly (iminocarbonate); poly(ethylene); and any derivatives, analogs, homologues, congeners, salts, copolymers and combinations thereof.

[0167] The polymers may also include, but are not limited to, poly(propylene) co- poly(ether-esters) such as, for example, poly(dioxanone) and polyethylene oxide) / poly(lactic acid); poly(anhydrides), poly(alkylene oxalates); poly(phosphazenes); poly(urethanes); silicones; silicone rubber; poly(esters); poly (olefins); copolymers of poly(isobutylene); copolymers of ethylene-alphaolefin; vinyl halide polymers and copolymers such as poly(vinyl chloride); poly(vinyl ethers) such as, for example, poly(vinyl methyl ether); poly(vinylidene halides) such as, for example, poly(vinylidene chloride); poly (acrylonitrile); poly(vinyl ketones); poly(vinyl aromatics) such as poly (styrene); poly(vinyl esters) such as poly(vinyl acetate); copolymers of vinyl monomers and olefins such as poly(ethylene-co-vinyl alcohol) (EVAL), copolymers of acrylonitrile -styrene, ABS resins, and copolymers of ethylene-vinyl acetate; and any derivatives, analogs, homologues, congeners, salts, copolymers and combinations thereof.

[0168] The polymers may further include, but are not limited to, poly(amides) such asNylon 66 and poly(caprolactam); alkyd resins; polycarbonate s); poly(oxymethylenes); poly(imides); poly(ester amides); poly(ethers) including poly(alkylene glycols) such as, for example, polyethylene glycol) and polypropylene glycol); epoxy resins; polyurethanes; rayon; rayon-triacetate; biomolecules such as, for example, fibrin, fibrinogen, starch, poly(amino acids); peptides, proteins, gelatin, chondroitin sulfate, dermatan sulfate (a copolymer of D- glucuronic acid or L-iduronic acid and N-acetyl-D-galactosamine), collagen, hyaluronic acid, and glycosaminoglycans; other polysaccharides such as, for example, poly(N- acetylglucosamine), chitin, chitosan, cellulose, cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellophane, cellulose nitrate, cellulose propionate, cellulose ethers, and carboxymethylcellulose; and any derivatives, analogs, homologues, congeners, salts, copolymers and combinations thereof.

[0169] As used herein, a processor 145, a signal processor 120, and a controller 125 may be implemented using any type of digital or analog electronic or other circuitry which is arranged, configured, designed, programmed or otherwise adapted to perform any portion of the signal processing, image generation, and beamforming (including delay calculations) described herein. As the term processor and / or controller is used herein, a processor 145, a signal processor 120, and / or a controller 125 may include use of a single integrated circuit ("IC"), or may include use of a plurality of integrated circuits or other electronic componentsconnected, arranged or grouped together, such as processors, controllers, microprocessors, digital signal processors ("DSPs"), parallel processors, multiple core processors, custom ICs, application specific integrated circuits ("ASICs"), field programmable gate arrays ("FPGAs"), adaptive computing ICs, discrete electronic components, and any associated memory (such as RAM, DRAM and ROM), and other ICs and components, whether analog or digital. As a consequence, as used herein, the term processor should be understood to equivalently mean and include a single IC, or arrangement of custom ICs, ASICs, processors, microprocessors, controllers, FPGAs, adaptive computing ICs, or some other grouping of integrated circuits or discrete electronic components which perform the functions discussed above and further discussed below, and may further include any associated memory, such as microprocessor memory or additional RAM, DRAM, SDRAM, SRAM, MRAM, ROM, FLASH, EPROM or E2PROM. A processor 145, a signal processor 120, and / or a controller 125, with any associated memory, may be arranged, adapted or configured (via programming, FPGA interconnection, or hard-wiring) to perform any portion of the signal processing, image generation, and beamforming of the present disclosure, as described herein. For example, the methodology may be programmed and stored, in a processor 145, a signal processor 120, and / or a controller 125 with its associated memory (and / or memory 185, 190, respectively) and other equivalent components, as a set of program instructions or other code (or equivalent configuration or other program) for subsequent execution when the processor 145, signal processor 120, and / or controller 125 is operative (i.e., powered on and functioning). Equivalently, when the processor 145, signal processor 120, and / or controller 125 may implemented in whole or part as FPGAs, custom ICs and / or ASICs, the FPGAs, custom ICs or ASICs also may be designed, configured and / or hard-wired to implement any portion of the personalization of search results and search result rankings of the present disclosure. For example, the processor 145, signal processor 120, and / or controller 125 may be implemented as an arrangement of analog and / or digital circuits, controllers, microprocessors, DSPs and / or ASICs, collectively referred to as a “processor”, or “controller” which are respectively hardwired, arranged, programmed, designed, adapted or configured to implement signal processing, image generation, and beamforming of the present disclosure, including possibly in conjunction with a memory 185, 190.

[0170] A memory 185, 190 and / or activation pattern registers 305 may be embodied as any type of data storage device, such as RAM, FLASH, DRAM, SDRAM, SRAM, MRAM, FeRAM, ROM, EPROM or E2PROM, and is utilized for data storage, and also may be utilized to store any data, activation patterns, program instructions or configurations which may be utilized by a processor 145, a signal processor 120, a controller 125, and / or activation patternselection logic 310. More specifically, the memory 185, 190 and / or activation pattern registers 305 may be embodied in any number of forms, including within any nontransitory, machine- readable data storage medium, memory device or other storage or communication device for storage or communication of information, currently known or which becomes available in the future, including, but not limited to, a memory integrated circuit (“IC”), or memory portion of an integrated circuit (such as the resident memory within a processor 145, signal processor 120, and / or controller 125), whether volatile or non-volatile, whether removable or non-removable, including without limitation RAM, FLASH, DRAM, SDRAM, SRAM, MRAM, FeRAM, ROM, EPROM or E2PROM, or any other form of memory or data storage device, as the case may be (depending upon various form factors, for example), such as a magnetic hard drive, an optical drive, a magnetic disk or tape drive, a hard disk drive, other machine-readable storage or memory media such as a floppy disk, a CDROM, a CD-RW, digital versatile disk (DVD) or other optical memory, or any other type of memory, storage medium, or data storage apparatus or circuit, which is known or which becomes known, depending upon the selected embodiment. The memory 185, 190 and / or activation pattern registers 305 may store data in any way or configuration, including as various look up tables, parameters, coefficients, databases, other information and data, programs or instructions (of the software of the present invention), and other types of tables such as database tables or any other form of data repository.

[0171] The communication and user interface (I / O) circuits 130, 135, 140, 300 may be implemented as known or may become known in the art, and may include impedance matching capability, voltage rectification circuitry, voltage translation for a low voltage processor to interface with a higher voltage control bus for example, various switching mechanisms (e.g., transistors) to turn various lines or connectors on or off in response to signaling from a processor 145, signal processor 120, and / or controller 125, other control logic circuitry, and / or physical coupling mechanisms. In addition, the communication and user interface (I / O) circuits 130, 135, 140, 300 are also configured to receive and / or transmit signals, such as through hardwiring or RF signaling, for example, to receive and transmit information in real-time, also for example. The communication and user interface (I / O) circuits 130, 135, 140, 300 are utilized for appropriate connection to a relevant channel, network or bus; for example, the communication and user interface (I / O) circuits 130, 135, 140, 300 may provide impedance matching, drivers and other functions for a wireline interface, may provide demodulation and analog to digital conversion for a wireless interface, and may provide a physical interface for the memory 185, 190 and / or activation pattern registers 305 with other devices. In general, the communication and user interface (I / O) circuits 130, 135, 140, 300 are used to receive andtransmit data, depending upon the selected embodiment, including activation patterns, control messages, and other pertinent information.

[0172] As indicated above, the processor 145, signal processor 120, controller 125, and / or activation pattern selection logic 310 is or are hard-wired, configured or programmed, using software and data structures of the invention, for example, to perform any portion of the signal processing, image generation, and beamforming, of the present disclosure. As a consequence, portions of the system and method of the present disclosure may be embodied as software which provides such programming or other instructions, such as a set of instructions and / or metadata embodied within a nontransitory computer-readable medium, discussed above. In addition, metadata may also be utilized to define the various data structures of a look up table or a database. Such software may be in the form of source or object code, by way of example and without limitation. Source code further may be compiled into some form of instructions or object code (including assembly language instructions or configuration information). The software, source code or metadata of the present invention may be embodied as any type of code, such as C, C++, C#, Javascript, Adobe Flash, Silverlight, SystemC, LISA, XML, Java, Brew, SQL and its variations (e.g., SQL 99 or proprietary versions of SQL), DB2, Oracle, or any other type of programming language which performs the functionality discussed herein, including various hardware definition or hardware modeling languages (e.g., Verilog, VHDL, RTL) and resulting database files (e.g., GDSII). As a consequence, “software”, “program”, “computer program”, or a “module”, “program module”, “software module”, as used equivalently herein, means and refers to any programming language, of any kind, with any syntax or signatures, which provides or can be interpreted to provide the associated functionality or methodology specified (when instantiated or loaded into a processor or computer and executed, including the processor 145, signal processor 120, controller 125, and / or activation pattern selection logic 310, for example). In addition, any of such program or software modules may be combined or divided in any way. For example, a larger module combining first and second functions is considered equivalent to a first module which performs the first function and a separate second module which performs the second function.

[0173] The present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. In this respect, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of components set forth above and below, illustrated in the drawings, or as described in the examples. Systems, methods and apparatuses consistent with the present invention are capable of other embodiments and of being practiced and carried out in various ways.

[0174] Although the invention has been described with respect to specific embodiments thereof, these embodiments are merely illustrative and not restrictive of the invention. In the description herein, numerous specific details are provided, such as examples of electronic components, electronic and structural connections, materials, and structural variations, to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, components, materials, parts, etc. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention. In addition, the various Figures are not drawn to scale and should not be regarded as limiting.

[0175] Reference throughout this specification to “one embodiment”, “an embodiment”, or a specific “embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments, and further, are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner and in any suitable combination with one or more other embodiments, including the use of selected features without corresponding use of other features. In addition, many modifications may be made to adapt a particular application, situation or material to the essential scope and spirit of the present invention. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered part of the spirit and scope of the present invention.

[0176] It will also be appreciated that one or more of the elements depicted in theFigures can also be implemented in a more separate or integrated manner, or even removed or rendered inoperable in certain cases, as may be useful in accordance with a particular application. Integrally formed combinations of components are also within the scope of the invention, particularly for embodiments in which a separation or combination of discrete components is unclear or indiscernible. In addition, use of the term “coupled” herein, including in its various forms such as “coupling” or “couplable”, means and includes any direct or indirect electrical or structural coupling, connection or attachment, or adaptation or capability for such a direct or indirect electrical or structural coupling, connection or attachment, including integrally formed components and components which are coupled via or through another component.

[0177] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated. In addition, every intervening sub-range within range is contemplated, in any combination, and is within the scope of the disclosure. For example, for the range of 5 - 10, the sub-ranges 5 - 6, 5 - 7, 5 - 8, 5 - 9, 6 - 7, 6 - 8, 6 - 9, 6 - 10, 7 - 8, 7 - 9, 7 - 10, 8 - 9, 8 - 10, and 9 - 10 are contemplated and within the scope of the disclosed range.

[0178] Furthermore, any signal arrows in the drawings / Figures should be considered only exemplary, and not limiting, unless otherwise specifically noted. Combinations of components of steps will also be considered within the scope of the present invention, particularly where the ability to separate or combine is unclear or foreseeable. The disjunctive term “or”, as used herein and throughout the claims that follow, is generally intended to mean “and / or”, having both conjunctive and disjunctive meanings (and is not confined to an “exclusive or” meaning), unless otherwise indicated. As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Also as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[0179] The foregoing description of illustrated embodiments of the present invention, including what is described in the summary or in the abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. From the foregoing, it will be observed that numerous variations, modifications and substitutions are intended and may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific methods and apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.

Claims

CLAIMS:

1. An intravascular ultrasound catheter apparatus, comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart within the elongated housing, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured to activate one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

2. The intravascular ultrasound catheter apparatus of claim 1, wherein the plurality of ultrasonic transducer controllers are distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements.

3. The intravascular ultrasound catheter apparatus of claim 1, further comprising: a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with a catheter guidewire.

4. The intravascular ultrasound catheter apparatus of claim 3, further comprising: a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance.

5. The intravascular ultrasound catheter apparatus of claim 1, wherein the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate the focused ultrasonic beam having a user-selectable or user-programmable focalpoint, focal distance or focal length and a user-selectable or user-programmable scan line center.

6. The intravascular ultrasound catheter apparatus of claim 1, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures of the ultrasonic transducer assembly, wherein each sub-aperture, of the plurality of sub-apertures, comprises a predetermined number of serially or sequentially adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements.

7. The intravascular ultrasound catheter apparatus of claim 6, wherein each subaperture, of the plurality of sub-apertures, is offset from an adjacent sub-aperture, of the plurality of sub-apertures, by one ultrasonic transducer element of the plurality of ultrasonic transducer elements.

8. The intravascular ultrasound catheter apparatus of claim 6, wherein the plurality of ultrasonic transducer controllers are further configured to activate the one or more ultrasonic transducer elements of the selected sub-aperture, followed by activating one or more ultrasonic transducer elements of a next adjacent sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, to successively generate a series of focused ultrasonic beams around the entire circumferential array of the plurality of ultrasonic transducer elements.

9. The intravascular ultrasound catheter apparatus of claim 6, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically activate a plurality of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

10. The intravascular ultrasound catheter apparatus of claim 1, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns.

11. The intravascular ultrasound catheter apparatus of claim 10, wherein each predetermined activation pattern, of the plurality of predetermined activation patterns, comprises: a selection of ultrasonic transducer elements for activation, from the corresponding subset of ultrasonic transducer elements.

12. The intravascular ultrasound catheter apparatus of claim 10, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises one or more memory circuits or registers, and wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to store the plurality of predetermined activation patterns in the one or more memory circuits or registers.

13. The intravascular ultrasound catheter apparatus of any of the preceding claims 1 - 12, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, by switching an activation signal or voltage to the one or more ultrasonic transducer elements.

14. The intravascular ultrasound catheter apparatus of claim 10, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a plurality of switches, each switch of the plurality of switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more registers or memory circuits configured to store the plurality of predetermined activation patterns.

15. The intravascular ultrasound catheter apparatus of claim 10, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more registers or memory circuits configured to store the plurality of predetermined activation patterns.

16. The intravascular ultrasound catheter apparatus of claim 15, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, further comprises: an activation pattern selection logic circuit configured to select the selected predetermined activation pattern from the one or more registers or memory circuits; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selected predetermined activation pattern.

17. The intravascular ultrasound catheter apparatus of claim 15, wherein each analog switch, of the plurality of analog switches, comprises a transmission gate configured, when in an on state, to conduct an activation signal or voltage to the selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements.

18. The intravascular ultrasound catheter apparatus of claim 15, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is configured to respond to a command to simultaneously or concurrently switch, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to a selected predetermined activation pattern of the plurality of predetermined activation patterns.

19. A method of operating the intravascular ultrasound catheter apparatus of claim 15, comprising: using a selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, receiving a selection of an activation pattern, of the plurality of predetermined activation patterns; using the selected ultrasonic transducer controller, receiving an on command; in response to the on command, using the selected ultrasonic transducer controller, simultaneously or concurrently switching, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selected activation pattern; and using the selected ultrasonic transducer controller, receiving one or more activation signals or voltages and transmitting the received one or more activation signals or voltages through the subset of analog switches to the selection of ultrasonic transducer elements of the selected activation pattern.

20. The method of claim 19, further comprising: using the selected ultrasonic transducer controller, receiving an off command; and in response to the off command, using the selected ultrasonic transducer controller, simultaneously or concurrently switching, to an off and nonconducting state, the subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selected activation pattern.

21. The intravascular ultrasound catheter apparatus of claim 1, further comprising: a catheter control connector arranged proximally within the elongated housing and coupled to the plurality of ultrasonic transducer controllers; a plurality of analog transmit and receive coaxial wires or lines coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; a plurality of supply voltage lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; and a plurality of digital logic lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers.

22. The intravascular ultrasound catheter apparatus of claim 21, wherein the plurality of ultrasonic transducer elements comprises at least forty to eighty ultrasonic transducer elements, the plurality of ultrasonic transducer controllers comprises at least four to six ultrasonic transducer controllers, the plurality of analog transmit and receive coaxial wires or lines comprises four or fewer analog transmit and receive coaxial wires or lines, the plurality of supply voltage lines or wires comprises four or fewer supply voltage lines or wires, and the plurality of digital logic lines or wires comprises four or fewer digital logic lines or wires.

23. The intravascular ultrasound catheter apparatus of claim 1, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is coupled in series with the corresponding subset of ultrasonic transducer elements; each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is coupled in parallel with all other ultrasonic transducer controllers, of the plurality of ultrasonic transducer controllers; and wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is operable independently from each of the other ultrasonic transducer controllers of the plurality of ultrasonic transducer controllers.

24. The intravascular ultrasound catheter apparatus of claim 1, wherein each corresponding subset of the plurality of ultrasonic transducer elements comprises a plurality of serially or sequentially adjacent ultrasonic transducer elements.

25. An intravascular ultrasound (“IVUS”) system, comprising: an IVUS console comprising: a processor configured to generate a plurality of activation signals and a plurality of addressable commands; a host communication interface coupled to the processor, the host communication interface configured to transmit the plurality of activation signals and the plurality of addressable commands; an image display coupled to the processor; and a first memory circuit coupled to the processor; a patient interface ultrasound module coupleable to the host communication interface; and an IVUS catheter removably coupleable to the patient interface ultrasound module, the IVUS catheter comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command of the plurality of addressable commands, to switch or conduct one or more activation signals, of the plurality of activation signals, to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements to generate a focused ultrasonic beam.

26. The intravascular ultrasound system of claim 25, wherein the IVUS catheter further comprises:a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with a catheter guidewire.

27. The intravascular ultrasound system of claim 26, wherein the IVUS catheter further comprises: a plurality of pad-printed radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each pad-printed radiopaque marker, of the plurality of pad- printed radiopaque markers, having a predetermined size, and each pad-printed radiopaque marker, of the plurality of pad-printed radiopaque markers, spaced apart longitudinally from an adjacent pad-printed radiopaque marker, of the plurality of pad-printed radiopaque markers, by a predetermined distance.

28. The intravascular ultrasound system of claim 25, wherein the plurality of ultrasonic transducer controllers are further configured to switch the one or more activation signals to the one or more ultrasonic transducer elements to generate the focused ultrasonic beam having a user-selectable or user-programmable focal point, focal distance or focal length and a user-selectable or user-programmable scan line center.

29. The intravascular ultrasound system of claim 25, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to switch the one or more activation signals to the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures of the ultrasonic transducer assembly.

30. The intravascular ultrasound system of claim 29, wherein each sub-aperture, of the plurality of sub-apertures, is offset from an adjacent sub-aperture, of the plurality of subapertures, by one ultrasonic transducer element of the plurality of ultrasonic transducer elements.

31. The intravascular ultrasound system of claim 29, wherein the plurality of ultrasonic transducer controllers are further configured to switch the one or more activation signals to one or more ultrasonic transducer elements of the selected sub-aperture, followed by switching the one or more activation signals to one or more ultrasonic transducer elements of a next sub-aperture, sequentially for all sub-apertures of the plurality of sub-apertures, tosuccessively generate a series of focused ultrasonic beams around the entire circumferential array of the plurality of ultrasonic transducer elements.

32. The intravascular ultrasound system of claim 29, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to activate the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of subapertures of the ultrasonic transducer assembly, wherein each sub-aperture, of the plurality of sub-apertures, comprises a predetermined number of serially or sequentially adjacent ultrasonic transducer elements of the plurality of ultrasonic transducer elements.

33. The intravascular ultrasound system of claim 25, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to simultaneously and symmetrically switch or conduct the one or more activation signals to the one or more ultrasonic transducer elements of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

34. The intravascular ultrasound system of claim 25, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to switch or conduct the one or more activation signals to the one or more ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns.

35. The intravascular ultrasound system of claim 34, wherein each predetermined activation pattern, of the plurality of predetermined activation patterns, comprises: a selection of ultrasonic transducer elements for activation, from the plurality of ultrasonic transducer elements; an ordering of the selected ultrasonic transducer elements for activation; and a plurality of predetermined time delays for sequential activation of the ordered, selected ultrasonic transducer elements.

36. The intravascular ultrasound system of claim 35, wherein the processor is further configured to store the plurality of predetermined activation patterns in the first memory circuit.

37. The intravascular ultrasound system of claim 35, wherein the processor is configured to determine the plurality of predetermined activation patterns and to transmit the selection of ultrasonic transducer elements for activation, for each predetermined activation pattern of the plurality of predetermined activation patterns, via the patient interface ultrasound module, to one or more corresponding ultrasonic transducer controllers of the plurality of ultrasonic transducer controllers.

38. The intravascular ultrasound system of claim 37, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises one or more second memory circuits or registers, and wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is further configured to receive a selection of ultrasonic transducer elements for activation for each received predetermined activation pattern, of the plurality of predetermined activation patterns, and to store the selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns, in the one or more second memory circuits or registers.

39. The intravascular ultrasound system of claim 35, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a plurality of switches, each switch of the plurality of switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store the selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns.

40. The intravascular ultrasound system of claim 35, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selectedultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store the selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns.

41. The intravascular ultrasound system of claim 40, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, further comprises: an activation pattern selection logic circuit configured to select the selection of ultrasonic transducer elements for activation from the one or more second memory circuits or registers; and a switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selection of ultrasonic transducer elements for activation.

42. The intravascular ultrasound system of claim 40, wherein each analog switch, of the plurality of analog switches, comprises a transmission gate configured, when in an on state, to conduct an activation signal or voltage to the selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements.

43. The intravascular ultrasound system of claim 40, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, is configured to respond to an on command to simultaneously or concurrently switch, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selection of ultrasonic transducer elements for activation of the plurality of predetermined activation patterns.

44. A method of operating the intravascular ultrasound system of claim 40, comprising: using the IVUS console, transmitting a memory pointer to a selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers; using the IVUS console, transmitting an on command to the selected ultrasonic transducer controller; using the selected ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, receiving the memory pointer and the on command;using the selected ultrasonic transducer controller, in response to the memory pointer, selecting from the one or more second memory circuits or registers a selection of ultrasonic transducer elements for activation corresponding to the memory pointer; and using the selected ultrasonic transducer controller, in response to the on command, simultaneously or concurrently switching, to an on and conducting state, a subset of analog switches of the plurality of analog switches, the subset of analog switches corresponding to the selection of ultrasonic transducer elements for activation.

45. The method of claim 44, further comprising: using the IVUS console, transmitting a first activation signal or voltage to the selected ultrasonic transducer controller to simultaneously and symmetrically activate a first pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures; and following one or more predetermined time delays, using the IVUS console, transmitting a second or next activation signal or voltage to the selected ultrasonic transducer controller to simultaneously and symmetrically activate a second or next pair of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of a plurality of sub-apertures.

46. The method of claim 45, further comprising: following transmission of a last activation signal or voltage, using the IVUS console, receiving, through the subset of analog switches in the on and conducting state, one or more ultrasound signals from the corresponding subset of the plurality of ultrasonic transducer elements.

47. The method of claim 46, further comprising: using the IVUS console, transmitting an off command to the selected ultrasonic transducer controller; and using the selected ultrasonic transducer controller, in response to the off command, simultaneously or concurrently switching, to an off and nonconducting state, the subset of analog switches.

48. A method of operating the intravascular ultrasound system of claim 40, comprising:in a first digital phase, using the selected ultrasonic transducer controller, switching one or more subsets of analog switches to an on and conducting state; in an analog phase when the one or more subsets of analog switches are in the on and conducting state, using the IVUS console, transmitting a plurality of activation signals to the selected ultrasonic transducer controller to sequentially activate one or more pairs of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within a selected sub-aperture of a plurality of sub-apertures, and following transmission of the plurality of activation signals, using the IVUS console, receiving, through the subset of analog switches in the on and conducting state, one or more ultrasound signals from the corresponding subset of the plurality of ultrasonic transducer elements; and in a second digital phase following reception of the one or more ultrasound signals, using the selected ultrasonic transducer controller, switching the one or more subsets of analog switches to an off and nonconducting state.

49. A method of using the system of claim 25 in a human or veterinary subject, comprising: using the IVUS console, determining or selecting one or more activation patterns for one or more ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, having one or more selected focal points and scan lines; using the IVUS console, loading the one or more activation or energizing patterns into the IVUS catheter; inserting and positioning the IVUS catheter at a first selected or desired vasculature location in the subject; using the IVUS console, activating the one or more ultrasonic transducer elements according to the selected activation pattern; using the IVUS console, receiving signals via the IVUS catheter from reflected ultrasound waves; and when no additional images are to be obtained, removing the IVUS catheter from the subject.

50. The method of using the system of claim 49, further comprising: when additional images are to be obtained, pulling the IVUS catheter to a second or next selected or desired vasculature location in the subject; using the IVUS console, activating the one or more ultrasonic transducer elements according to the selected activation pattern; andusing the IVUS console, receiving signals via the IVUS catheter from reflected ultrasound waves.

51. The intravascular ultrasound system of claim 25, wherein the IVUS console is further configured to sequentially transmit, according to one or more predetermined time delays, a plurality of activation signals to the selected ultrasonic transducer controller to sequentially activate one or more pairs of ultrasonic transducer elements, of the corresponding subset of the plurality of ultrasonic transducer elements, within the selected sub-aperture of the plurality of sub-apertures of the ultrasonic transducer assembly.

52. The intravascular ultrasound system of claim 25, wherein the IVUS catheter further comprises: a catheter control connector arranged proximally within the elongated housing and coupled to the plurality of ultrasonic transducer controllers; a plurality of analog transmit and receive coaxial wires or lines coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; a plurality of supply voltage lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers; and a plurality of digital logic lines or wires coupled between the catheter control connector and the plurality of ultrasonic transducer controllers.

53. An intravascular ultrasound (“IVUS”) system, comprising: an IVUS console comprising: a processor configured to generate a plurality of activation signals or voltages, a plurality of addressable commands, and a plurality of predetermined activation patterns; a host communication interface coupled to the processor, the host communication interface configured to transmit the plurality of activation signals, the plurality of addressable commands, and the plurality of predetermined activation patterns; an image display coupled to the processor; and a first memory circuit coupled to the processor, the first memory circuit configured to store a plurality of predetermined activation patterns;a patient interface ultrasound module coupleable to the host communication interface; and an IVUS catheter removably coupleable to the patient interface ultrasound module, the IVUS catheter comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with a catheter guidewire, the tubular inner wall having a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command of the plurality of addressable commands, to switch or conduct one or more activation signals or voltages, of the plurality of activation signals or voltages, to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements, according to a selected, received predetermined activation pattern of the plurality of predetermined activation patterns, to generate a focused ultrasonic beam, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; and one or more second memory circuits or registers configured to store a selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns.

54. An intravascular ultrasound catheter apparatus insertable into a human or veterinary subject along a catheter guidewire, comprising: an elongated housing having a first, distal end and a second, proximal end, the elongated housing having a first, outer lumen; a tubular inner wall arranged within the first, outer lumen, the tubular inner wall having a second, inner lumen configured to slidably engage with the catheter guidewire, the tubular inner wall having a plurality of radiopaque markers arranged and coupled to an outer surface of the tubular inner wall, each radiopaque marker, of the plurality of radiopaque markers, having a predetermined size, and each radiopaque marker, of the plurality of radiopaque markers, spaced apart longitudinally from an adjacent radiopaque marker, of the plurality of radiopaque markers, by a predetermined distance; a circumferential array of a plurality of ultrasonic transducer elements arranged distally around the elongated housing; and a plurality of ultrasonic transducer controllers distributed and spaced apart circumferentially within the elongated housing and adjacent the circumferential array of the plurality of ultrasonic transducer elements, each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, coupled to a corresponding subset of ultrasonic transducer elements, of the plurality of ultrasonic transducer elements, and each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, configured, in response to receiving an on command, to switch or conduct one or more activation signals to one or more ultrasonic transducer elements of the corresponding subset of ultrasonic transducer elements, according to a selected predetermined activation pattern of a plurality of predetermined activation patterns, to generate a focused ultrasonic beam, wherein each ultrasonic transducer controller, of the plurality of ultrasonic transducer controllers, comprises: a crosspoint switch matrix circuit coupled to the corresponding subset of the plurality of ultrasonic transducer elements, the crosspoint switch matrix comprising a plurality of analog switches, each analog switch of the plurality of analog switches coupled to a selected ultrasonic transducer element of the corresponding subset of ultrasonic transducer elements; one or more second memory circuits or registers configured to store a selection of ultrasonic transducer elements for activation, for each received predetermined activation pattern of the plurality of predetermined activation patterns; an activation pattern selection logic circuit configured to select the selection of ultrasonic transducer elements for activation from the one or more second memory circuits or registers; anda switch decoder circuit configured to select one or more analog switches of the plurality of analog switches in response to the selection of ultrasonic transducer elements for activation.

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