Diagnostic and therapeutic ultrasound catheter with single transducer

Abstract

A medical device (1030) is described. The medical device (1030) includes a catheter (1036) body having a lumen (406) with a distal end (1004) and a proximal end. A transducer (1034) disposed at or near the distal end (1004) of the catheter (1036) body, and the transducer (1034) is adapted to emit and receive ultrasound waves to treat tissue and / or measure blood velocity and / or image tissue with the same transducer (1034).

Description

DIAGNOSTIC AND THERAPEUTIC ULTRASOUND CATHETERWITH SINGLE TRANSDUCERBACKGROUND

[0001] Ultrasound has been used clinically to measure flow velocity to diagnose various conditions such as coronary microvascular disease. It is also useful to provide relevant diagnostic information to clinicians treating disease in the peripheral vasculature. In the peripheral vasculature there are opportunities for diagnostic information to add value throughout the clinical procedure. For example, flow measurements may be helpful in diagnosing clinical significance of a lesion prior to treatment, or whether adequate flow has been restored following treatment. Flow measurements may also benefit the clinician between treatment modalities, for example in venous interventions following thrombectomy and high pressure venoplasty to determine whether there is adequate inflow to support placement of an iliac stent.

[0002] In addition to measuring flow velocity, ultrasound has been used clinically or in research applications to in therapeutic applications via thermal or cavitation treatment. For example, in renal denervation procedures, ultrasound can be used to heat and ablate the nerves surrounding the renal artery.

[0003] Using known devices, it is often necessary to exchange elements used in the procedure, including the ultrasound transducer. As such, the clinician must withdraw the catheter used for an ultrasound-based treatment, for example, and replace the ultrasound transducer with another ultrasound transducer used to measure fluid flow. As will be appreciated, having to exchange elements to carry out different procedures is, among other drawbacks, inefficient and can result in delays in completing the treatment.

[0004] What is needed, therefore, is a medical device that enables therapeutic procedures and measurement of blood flow that overcomes at least the noted drawbacks of the known approaches described above.SUMMARY

[0005] In accordance with a representative embodiment, a medical device is disclosed. The medical device comprises: a catheter body comprising a lumen comprising a distal end and aproximal end; and a transducer disposed at or near the distal end of the catheter body. The transducer is adapted to emit ultrasound waves to treat tissue and / or emit and receive ultrasound waves measure blood velocity and / or image tissue with the same transducer.

[0006] In accordance with another representative embodiment, a method of carrying out a medical procedure is disclosed. The method comprises: providing a catheter body comprising a lumen comprising a distal end and a proximal end; providing a transducer disposed at or near the distal end of the catheter body; and emitting ultrasound waves to treat tissue and / or emit and receive ultrasound waves measure blood velocity and / or image tissue with the same transducer.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The example embodiments are best understood from the following detailed description when read with the accompanying drawing figures. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. Wherever applicable and practical, like reference numerals refer to like elements.

[0008] Fig. 1 A is a perspective view of a catheter lab comprising a medical system comprising a medical device in accordance with a representative embodiment.

[0009] Fig. IB is a simplified block diagram of a medical system comprising a medical device in accordance with a representative embodiment.

[0010] Fig. 2A is a perspective view of a catheter lab comprising a medical system comprising a medical device in accordance with a representative embodiment.

[0011] Fig. 2B is a simplified block diagram of a medical system comprising a medical device in accordance with a representative embodiment.

[0012] Fig. 3 is a simplified block diagram of front-end and back-end electronics used in A-line imaging in a medical system in accordance with a representative embodiment

[0013] Fig. 4A is a conceptual view of a medical device deployed for treatment of a patient in accordance with a representative embodiment.

[0014] Fig. 4B is a close-up view of the portions of the medical device of Fig. 4A in accordance with a representative embodiment.

[0015] Fig. 4C is a perspective view in partial cross-section a transducer of a medical device in accordance with another representative embodiment.

[0016] Fig. 5A is a perspective view in partial cross-section of a transducer of a medical device in accordance showing excitation of transducer elements in accordance with a representative embodiment.

[0017] Fig. 5B is a graph of acoustic pressure versus frequency of a transducer in accordance with a representative embodiment.

[0018] Fig. 6A shows an acoustic pressure (Pa) profile of a medical device without a guide wire disposed in a catheter in accordance with another representative embodiment.

[0019] Fig. 6B shows a temperature profile (°C) of the medical device of Fig. 5A in accordance with a representative embodiment.

[0020] Fig. 7A shows an acoustic profile (Pa) versus angle and distance of a transducer of a medical device in accordance with a representative embodiment.

[0021] Fig. 7B shows A-line image generation of a transducer of a medical device in accordance with a representative embodiment.

[0022] Fig. 8A is a perspective view in partial cross-section of three concentric ring transducers of a medical device showing excitation of the three ring transducer elements in accordance with a representative embodiment.

[0023] Fig. 8B is a graph of acoustic pressure versus frequency of the medical device of Fig. 9 A in accordance with a representative embodiment.

[0024] Fig. 9A is a perspective view in partial cross-section of a transducer of a medical device in accordance with another representative embodiment.

[0025] Fig. 9B shows an acoustic pressure (Pa) versus frequency of a transducer in accordance with a representative embodiment profile of a medical device comprising the transducer of Fig. 9A.

[0026] Fig. 10 is a cross-sectional view of a medical device comprising a ring transducer and an acoustically transparent element disposed at a distal end of the transducer in accordance with a representative embodiment.DETAILED DESCRIPTION

[0027] In the following detailed description, for the purposes of explanation and not limitation, representative embodiments disclosing specific details are set forth in order to provide athorough understanding of embodiments according to the present teachings. However, other embodiments consistent with the present disclosure that depart from specific details disclosed herein remain within the scope of the appended claims. Descriptions of known systems, devices, materials, methods of operation and methods of manufacture may be omitted so as to avoid obscuring the description of the representative embodiments. Nonetheless, systems, devices, materials and methods that are within the purview of one of ordinary skill in the art are within the scope of the present teachings and may be used in accordance with the representative embodiments. It is to be understood that the terminology used herein is for purposes of describing particular embodiments only and is not intended to be limiting. Definitions and explanations for terms herein are in addition to the technical and scientific meanings of the terms as commonly understood and accepted in the technical field of the present teachings.

[0028] It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the inventive concept.

[0029] As used in the specification and appended claims, the singular forms of terms ‘a’, ‘an’ and ‘the’ are intended to include both singular and plural forms, unless the context clearly dictates otherwise. Additionally, the terms “comprises,” and / or “comprising,” and / or similar terms when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] Unless otherwise noted, when an element or component is said to be “connected to”, “coupled to”, or “adjacent to” another element or component, it will be understood that the element or component can be directly connected or coupled to the other element or component, or intervening elements or components may be present. That is, these and similar terms encompass cases where one or more intermediate elements or components may be employed to connect two elements or components. However, when an element or component is said to be “directly connected” or “immediately adjacent” to another element or component, this encompasses only cases where the two elements or components are connected or disposedimmediately adjacent to each other without any intermediate or intervening elements or components.

[0031] As described herein in connection with various representative embodiments, the present teachings relate to a medical device and its method of use that enables the same ring transducer to be used for both therapeutic and diagnostic procedures to be carried out. In accordance with a representative embodiment, a medical device is adapted to measure blood velocity rates to provide diagnostic information to the clinician, both in venous and arterial peripheral vascular procedures while also incorporating a therapeutic solution to treat the disease that is identified. The medical device comprises a catheter having a ring transducer at its distal end that can be used for both ultrasound-based treatment (e.g., tissue ablation or cavitation to treat lesion and cross total occlusion (CTO, 1ST), or mild hyperthermia for collagen softening, or cauterization for vessel closure) and measure blood flow velocity (blood velocity). In addition, the same transducer may be used to provide imaging (e.g., A-line imaging). This imaging can be done before a treatment is begun to facilitate the treatment, as well as during the treatment and / or blood velocity measurement thereby providing direct feedback on therapy effectiveness and blood flow. As will be appreciated by one of ordinary skill in the art, the medical device of the various representative embodiments reduces the number of catheter exchanges required in known medical devices in order to use a different transducer for thermal treatment, blood velocity measurement, and / or imaging. Reducing the number of catheter exchanges in turn streamlines the procedure and allows the clinician to provide therapy in response to the diagnostic results. As such, the medical device of the various representative embodiments enables a therapeutic procedure (e.g., ablation, cavitation, hyperthermia, cauterization) and diagnostic procedure (measurement of blood flow velocity, or imaging, or both) with the same ring transducer disposed at or near the distal end of a catheter. Moreover, and as described more fully below, when a guidewire is disposed in the catheter, a comparatively wide ultrasound beam suitable for Doppler flow sensing is generated using the transducer of the medical device. Alternatively, the catheter can be deployed without a guide wire extending from the distal end. In this case, the same transducer used to create the comparatively wide ultrasound beam is adapted to focus the ultrasound waves and generate a comparatively high intensity spot in-front of the transducer to perform, for example, a thermal procedure such as ablation, or cauterization or cavitation. As such, through the use of the same transducer and with the comparatively simpleaction of introducing or removing a guidewire in the catheter deployed in a subject, different medical procedures with different objectives can be realized without the need to exchange catheters and transducers.

[0032] Among other clear improvements to the technical field of medical treatment and diagnostics, the medical device of the various representative embodiments enables the streamlining of the medical procedures and allow the clinician to provide therapy in response to the diagnostic results such as blood flow measured and images gathered by the device. As will be appreciated, not only does the use of the same transducer in the medical device of representative embodiment for various procedures both reduces both labor and component costs, but also the medical devices of the present teachings improve workflow of the treatment, imaging and blood velocity measurements. By contrast, other known medical devices will require the use of multiple medical devices for the various procedures, and the need to exchange catheters for each procedure.

[0033] Fig. 1A is a perspective view of a catheter lab 100 comprising a medical system 102 comprising a medical device (not shown in Fig. 1 A) in accordance with a representative embodiment.

[0034] The catheter lab 100 comprises a C-arm 101 or similar structure commonly used in a catheter lab to carry out various medical procedures. A patient 103 is shown on a table 105 with a display 109 disposed as shown.

[0035] The medical device is connected via a connector 106 to a patient interface module (PIM) 108, which in turn is connected to a console 110 of the medical system 102. The console 110 is local to the controller 116. In certain representative embodiments, the console 110 comprises a graphic user interface (GUI) and is connected to the controller 116 via a local wired interface such as an Ethernet cable or via a local wireless interface such as a Wi-Fi connection. As described more fully below, the console 110 may comprise a display, and through the GUI enables a user (e.g., a clinician / user) to provide inputs via the console 110 to the medical device 130. Moreover, the console 110 be interfaced with other user input devices by which users can input instructions, including mouses, keyboards, thumbwheels and so on. The display 112 of the console 110 may be a monitor such as a computer monitor, a display on a mobile device (e.g., part of the user input 214 described below), an augmented reality display, a television, an electronic whiteboard, or another screen configured to display electronic imagery. The console110 may also include one or more input interface(s) such as those noted above that may connect to other elements or components, as well as an interactive touch screen configured to display prompts to users and collect touch input from users. These interfaces may also be icons (not shown) on a display (not shown in Fig. 1A) via the GUI.

[0036] The PIM 108 is configured to send signal to and receive signals from the console 110 during deployment of the medical device and attendant procedures performed thereby. The console also comprises a display 112, which may comprise, for example, a GUI.

[0037] Fig. IB is a simplified block diagram the medical system 102 comprising a medical device 130 disposed in a vessel 132 in accordance with a representative embodiment. As described more fully below, the medical device comprises a transducer 134 disposed at or near a distal end of a catheter 136. Specifically, and as described more fully below in connection, in accordance with various representative embodiments, the transducer 134 comprises a ring transducer disposed at the distal end of the catheter 136, with the ring transducer having an inner radius that is substantially the same dimension as an inner radius of the catheter 136 and an outer radius having substantially the same dimension as an outer radius of the catheter 136. Alternatively, the transducer 134 comprises a ring transducer near the distal end of the catheter with ring transducer having an inner radius substantially the same dimension as the outer radius of the catheter 136.

[0038] As shown, the console 110 is connected to the display 112, which may also comprise a display. Just by way of illustration, the display 112 may comprise a graphic user interface (GUI) that enables the clinician or other operator to control the function of the medical device 130, carry out the desired medical procedures and gather data and images from the medical device 130 as described more fully herein. Alternatively, the display 112 may be one of a number of common devices used to provide inputs to the various components of the console 110 to carry out the various procedures. The console 110 may comprise a keyboard, a mouse and a separate display, for example, to enable the clinician or other operator to control the function of the medical device 130, carry out the desired medical procedures and gather data and images from the medical device 130.

[0039] The console 110 comprises a user input 114. The user input 114 allows the clinician to select the mode of operation of the medical device 130, and to select parameters to carry out various medical procedures using the medical device 130. Notably, the user input 114 may be aphysical button / switch or a software-based GUI. In accordance with a representative embodiment, the user input 114 allows the user to initiate medical procedures and select various parameters to carry out the medical procedures. As described more fully below, the user input 114 enables the clinician to carry out various actions during the medical procedure, including switching between a diagnostic mode such as blood flow sensing and blood velocity measurement and imaging, and a therapeutic mode such as tissue ablation. Moreover, various parameter may be input to carry out these modes of operation via the user input (e.g., user input 114 described below). As such, the user input 114 allows the user to select between a diagnostic mode and a therapeutic mode. The user input 114 also enables the user to select to measure blood flow (blood velocity) or to capture images, wherein in a therapeutic mode, the user input would allow the user to select an ultrasound-based therapy procedure such as ablation, cavitation, hyperthermia or cauterization. The ability to switch from one mode to another affords a significant improvement to the field of medical diagnosis and treatment. For example, the user input 114 allows the user to capture images with the medical device via the transducer. These images may then be provided to the display 112 and used by the clinician to carry out a therapeutic procedure, such as ablating a lesion in the vessel 132 using the same transducer in the medical device 130. After completing the ablation step, the clinician may again switch to measuring the blood flow (velocity) to determine whether the ablation was successful in improving the blood flow. Again, via the user input 114, the user switches the function of the transducer 134 from a therapeutic mode to a diagnostic mode to measure the blood flow.

[0040] The parameters selected by the clinician via the user input 114 are based on the selected procedure and provide a wide variety of options to the user when selecting therapeutic treatment or diagnostic measurement / imaging. For example, if the clinician elects to carry out a tissue ablation procedure, the parameters selected may include the desired acoustic power and therefore the needed electric power, the frequency of the ultrasound waves needed for the ablation step, continuous ultrasound wave or pulsed ultrasound wave ,the desired pulse repetition frequency and duty cycle, which, among other benefits described below, may be useful to prevent overheating of the transducer. Additionally, the parameters may be selected for a particular diagnostic procedure. For example, Doppler imaging may be desired. In this case, the gating of the signal may be selected, so the bursts of ultrasound energy have a desired pulse repetition frequency, duration and frequency. Moreover, in case of A-line imaging, while single-pulseemission may be useful in certain to provide higher resolution images, whereas double-pulse imaging is preferred for penetration mode. As such, the selection of these and other various parameters not only allow the selection of the mode of operation (therapeutic or diagnostic), but also allows the particular characteristics of the selected procedure to be set.

[0041] The selected mode and parameters provided at the user input are provided to a controller 116, which comprises a processor (not shown as part of the controller 116), and a memory (not shown as part of the controller 116), which stores computer-executable instructions (code). In accordance with representative embodiments described more fully below, these instructions, when executed by the processor carry out various functions of representative embodiments described herein. As such, the memory may store a set of software instructions that can be executed to cause the medical system 102 to perform some or all aspects of certain methods or computer-based functions.

[0042] The controller 116 may be implemented by a computer that includes more elements than the controller of Fig. IB. Notably, in accordance with a representative embodiment, the controller may be remote to the medical system 102, and is adapted to control various aspects of the medical system 102 remotely via connections including both wired and wireless connections and protocols. In this sense, the controller 116, at least in part, is a specialty or particular computer useful in controlling the medical system 102.

[0043] The controller 116 may operate as a standalone device or may be connected, for example, using a network to other computer systems or peripheral devices. In representative embodiments, the medical system 102 performs logical processing based on digital signals received via an analog-to-digital converter. The controller 116 can also be implemented as or incorporated into various devices, such as a workstation that includes a controller, a stationary computer, a mobile computer, a personal computer (PC), a laptop computer, a tablet computer, or any other machine capable of executing a set of software instructions (sequential or otherwise) that specify actions to be taken by that machine. The controller 116 can be incorporated as or in a device that in turn is in an integrated system that includes additional devices. In an embodiment, the controller 116 can be implemented in a device that also provides video or data communication. Moreover, the controller 116 may be connected to components of the system via a local wired interface such as an Ethernet cable or via a local wireless interface such as a Wi-Fi connection.

[0044] The processor may be considered a representative example of a processor of thecontroller 116 and executes instructions to implement some or all aspects of methods and processes described herein. The processor is tangible and non-transitory. As used herein, the term “non-transitory” is to be interpreted not as an eternal characteristic of a state, but as a characteristic of a state that will last for a period. The term “non-transitory” specifically disavows fleeting characteristics such as characteristics of a carrier wave or signal or other forms that exist only transitorily in any place at any time. The processor is an article of manufacture and / or a machine component. The processor is configured to execute software instructions to perform functions as described in the various embodiments herein. The processor may be a general-purpose processor or may be part of an application specific integrated circuit (ASIC). The processor may also be a microprocessor, a microcomputer, a processor chip, a controller, a microcontroller, a digital signal processor (DSP), a state machine, or a programmable logic device. The processor may also be a logical circuit, including a programmable gate array (PGA), such as a field programmable gate array (FPGA), or another type of circuit that includes discrete gate and / or transistor logic. The processor may be a central processing unit (CPU), a graphics processing unit (GPU), or both. Additionally, any processor described herein may include multiple processors, parallel processors, or both. Multiple processors may be included in, or coupled to, a single device or multiple devices.

[0045] The term “processor” as used herein encompasses an electronic component able to execute a program or machine executable instruction. References to a processor should be interpreted to include more than one processor or processing core, as in a multi-core processor. A processor may also refer to a collection of processors within a single computer system or distributed among multiple computer systems.

[0046] The memory may include a main memory and / or a static memory, where memories in the medical system 102 communicate with each other and the processor via a bus (not shown). The memory may be considered a representative example of a memory of the controller 116, and store instructions used to implement some or all aspects of methods and processes described herein. Memories described herein are tangible storage mediums for storing data and executable software instructions and are non-transitory during the time software instructions are stored therein. As used herein, the term “non-transitory” is to be interpreted not as an eternal characteristic of a state, but as a characteristic of a state that will last for a period. The term “non- transitory” specifically disavows fleeting characteristics such as characteristics of a carrier waveor signal or other forms that exist only transitorily in any place at any time. The memory is an article of manufacture and / or machine components. The memory is a computer-readable medium from which data and executable software instructions can be read by a computer (e.g., by the processor of the controller 116). The memory may be implemented as one or more of randomaccess memory (RAM), read only memory (ROM), flash memory, electrically programmable read only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, a hard disk, a removable disk, tape, compact disk read only memory (CD- ROM), digital versatile disk (DVD), floppy disk, Blu-ray disk, or any other form of storage medium known in the art. The memory may be volatile or non-volatile, secure and / or encrypted, unsecure and / or unencrypted. The inventive concepts also encompass a computer readable medium that stores instructions that cause a data processing system (such as the DSP of an NV A) to execute the methods described herein. Finally, a computer readable medium is defined herein to be any medium that constitutes patentable subject matter under 35 U.S.C. §101 and excludes any medium that does not constitute patentable subject matter under 35 U.S.C. §101. Examples of such media include non-transitory media such as computer memory devices that store information in a format that is readable by a computer or data processing system. More specific examples of non-transitory media include computer disks and non-volatile memories.

[0047] Additionally, the memory is an example of a computer-readable storage medium. Computer memory is any memory which is directly accessible to a processor. Examples of computer memory include, but are not limited to RAM memory, registers, and register files. References to “memory” should be interpreted as possibly being multiple memories. The memory may for instance be multiple memories within the same computer system. The memory may also be multiple memories distributed amongst multiple computer systems or computing devices. Software instructions, when executed by the processor, perform one or more steps of the methods and processes as described herein. In an embodiment, the software instructions may reside all or in part within the memory and / or the processor during execution by the controller 116.

[0048] Commands from the controller 116 based on the selections at the user input 114 to an ultrasound (US) transmitter 118, which are provide to a send / receive switch 120 that controls the direction of flow of the US signals from the transmitter 118 and to a receiver 122.

[0049] US signals received at the transducer 134 of the medical device 130 are provided to thereceiver 121, and a processor 126 and a memory 128 are used to provide images and data to the display 112.

[0050] As shown, the console 110 is connected to the PIM 108, which in turn is connected to the connector 106. The connector 106 provides the necessary electrical connections to the transducer 134 of the medical device 130 so that the signals from the transmitter 118 are provided to the transducer 134 for emission of US signals for the procedure being carried out, and the reflected US signals from the transducer 134 are provided to the receiver 122 for processing and display at the display 112. In the present representative embodiment, the PIM 108 provides a relay function. Specifically, the PIM provide a location to connect the connector 106 at the bed-side. By contrast, the PIM described in connection with a representative embodiment of Fig. 2B provides additional functionality, as described below.

[0051] Fig. 2A is a perspective view of a catheter lab 200 comprising a medical system 202 comprising a medical device (not shown in Fig. 2A) in accordance with a representative embodiment. Certain aspects and details of the catheter lab 200 and medical system 202 are common to those described in connection with representative embodiments of Figs. 1 A and IB. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0052] The catheter lab 200 comprises a C-arm 201 or similar structure commonly used in a catheter lab to carry out various medical procedures. A patient 203 is shown on a table 205 with an imaging display 209 disposed as shown.

[0053] The medical device is connected via a connector 206 to a patient interface module (PIM) 208, which in turn is connected to a console 210 of the medical system 202. The console 210 is local to the controller 116. In certain representative embodiments, the console 210 comprises a GUI and is connected to the controller 116 via a local wired interface such as an Ethernet cable or via a local wireless interface such as a Wi-Fi connection. As described more fully below, the console 210 may comprise a display, and through the GUI enables a user (e.g., a clinician / user) to provide inputs via the console 119 to the medical device 230. Moreover, the console 210 be interfaced with other user input devices by which users can input instructions, including mouses, keyboards, thumbwheels and so on. The display of the console 210 may be a monitor such as a computer monitor, a display on a mobile device, an augmented reality display, a television, an electronic whiteboard, or another screen configured to display electronic imagery. The console210 may also include one or more input interface(s) such as those noted above that may connect to other elements or components, as well as an interactive touch screen configured to display prompts to users and collect touch input from users. These interfaces may also be icons (not shown) on a display (not shown in Fig. 2A) via the GUI.

[0054] As described more fully below, the PIM 208 is configured to send signal to and receive signals from the console 210 during deployment of the medical device and attendant procedures performed thereby. The console also comprises a display 212, which may comprise, for example, a graphic user interface (GUI).

[0055] As described more fully below, the display 212 enables the clinician to carry out various actions during the medical procedure, including switching between a diagnostic mode such as blood flow sensing and blood velocity measurement and imaging, and a therapeutic mode such as tissue ablation. Moreover, various parameter may be input to carry out these modes of operation via the display 212. Notably, the medical system 202 also comprises a table side module 223. As described more fully below, the table side module 223 allows the clinician to carry out a number of steps to carry out the desired procedures noted above. These include selection of and switching between diagnostic mode and therapeutic mode as well as selecting the various parameters for the selected diagnostic and therapeutic procedure being carried out. At the risk of repetition, these parameters are based on the selected procedure and provide a wide variety of options to the user when selecting therapeutic treatment or diagnostic measurement / imaging. For example, if the clinician elects to carry out a tissue ablation procedure, the parameters selected may include the desired acoustic power and therefore the needed electric power, the frequency of the ultrasound waves needed for the ablation step, continuous ultrasound wave or pulsed ultrasound wave , the desired pulse repetition frequency and duty cycle, which, among other benefits described below, may be useful to prevent overheating of the transducer. Additionally, the parameters may be selected for a particular diagnostic procedure. For example, Doppler imaging may be desired. In this case, the gating of the signal may be selected, so the bursts of ultrasound energy have a desired, pulse repetition frequency, duration and frequency. Moreover, in case of A-line imaging, while single-pulse emission may be useful in certain to provide higher resolution images, whereas double-pulse imaging is preferred for penetration mode. As such, the selection of these and other various parameters not only allow the selection of the mode of operation (therapeutic or diagnostic), butalso allows the particular characteristics of the selected procedure to be set.

[0056] Fig. 2B is a simplified block diagram the medical system 102 comprising a medical device 230 disposed in a vessel 232 in accordance with a representative embodiment. As described more fully below, the medical device comprises a transducer 234 disposed at or near a distal end of a catheter 236. Specifically, and as described more fully below in connection, in accordance with various representative embodiments, the transducer 234 comprises a ring transducer disposed at the distal end of the catheter 236, with the ring transducer having an inner radius that is substantially the same dimension as an inner radius of the catheter 236 and an outer radius having substantially the same dimension as an outer radius of the catheter 236. Alternatively, the transducer 234 comprises a ring transducer near the distal end of the catheter with ring transducer having an inner radius substantially the same dimension as the outer radius of the catheter 236.

[0057] As shown, the console 210 is connected to the display 212, which may also comprise a display. Just by way of illustration, the display 212 may comprise a graphic user interface (GUI) that enables the clinician or other operator to control the function of the medical device 230, carry out the desired medical procedures and gather data and images from the medical device 230 as described more fully herein. Alternatively, the display 212 may be one of a number of common devices used to provide inputs to the various components of the console 210 to carry out the various procedures. The console 210 may comprise a keyboard, a mouse and a separate display, for example, to enable the clinician or other operator to control the function of the medical device 230, carry out the desired medical procedures and gather data and images from the medical device 230.

[0058] In the presently described representative embodiment, the PIM 208 comprises certain components disposed in the console 110 of Figs. 1 A-1B. Commands from the controller 216 based on the selections at the user input 214 to a US transmitter 218, which are provided to a send / receive switch 220 that controls the direction of flow of the US signals from the transmitter 218 and to a receiver 222. US signals received at the transducer 234 of the medical device 230 are provided to the receiver 221, and a processor 226 and a memory 228 are used to provide images and data to the display 212.

[0059] As shown, the console 210 is connected to the PIM 208, which in turn is connected to the connector 206. The connector 206 provides the necessary electrical connections to thetransducer 234 of the medical device 230 so that the signals from the transmitter 218 are provided to the transducer 234 for emission of US signals for the procedure being carried out, and the reflected US signals from the transducer 234 are provided to the receiver 222 for processing and display at the display 212.

[0060] The medical system 202 comprises table side module 240, which comprises a user input 214. The table side module 240 is a portable device (e.g., a tablet computer or mobile phone) that is used by the clinician to carry out the desired medical procedure, including switching between modes of operation, and selecting parameters via the user input 214. As such, the user input 214 allows the clinician to select the mode of operation of the medical device 230, and to select parameters to carry out various medical procedures using the medical device 230. In accordance with a representative embodiment, the user input 214 allows the user to initiate medical procedures and select various parameters to carry out the medical procedures. As described more fully below, the user input 214 enables the clinician to carry out various actions during the medical procedure, including switching between a diagnostic mode such as blood flow sensing and blood velocity measurement and imaging, and a therapeutic mode such as tissue ablation. Moreover, various parameter may be input to carry out these modes of operation via the user input (e.g., user input 214 described below). As such, the user input 214 allows the user to select between a diagnostic mode and a therapeutic mode. The user input 214 also enables the user to select to measure blood flow (blood velocity) or to capture images, wherein in a therapeutic mode, the user input would allow the user to select a therapeutic ultrasound procedure such as ablation, cavitation, hyperthermia or cauterization. The ability to switch from one mode to another affords a significant improvement to the field of medical diagnosis and treatment. For example, the user input 214 allows the user to capture images with the medical device via the transducer. These images may then be provided to the display 212 and used by the clinician to carry out a therapeutic procedure, such as ablating a lesion in the vessel 232 using the same transducer in the medical device 230. After completing the ablation step, the clinician may again switch to measuring the blood flow (velocity) to determine whether the ablation was successful in improving the blood flow. Again, via the user input 214, the user switches the function of the transducer 234 from a therapeutic mode to a diagnostic mode to measure the blood flow.

[0061] The parameters selected by the clinician via the user input 214 are based on the selected procedure and provide a wide variety of options to the user when selecting therapeutic treatmentor diagnostic measurement / imaging. For example, if the clinician elects to carry out a tissue ablation procedure, the parameters selected may include the desired acoustic power and therefore the needed electric power, the frequency of the ultrasound waves needed for the ablation step, continuous ultrasound wave or pulsed ultrasound wave , the desired pulse repetition frequency and duty cycle, which, among other benefits described below, may be useful to prevent overheating of the transducer. Additionally, the parameters may be selected for a particular diagnostic procedure. For example, Doppler imaging may be desired. In this case, the gating of the signal may be selected, so the bursts of ultrasound energy have a desired, repetition frequency, duration and frequency. Moreover, in case of A-line imaging, while single-pulse emission may be useful in certain to provide higher resolution images, whereas double-pulse imaging is preferred for penetration mode. As such, the selection of these and other various parameters not only allow the selection of the mode of operation (therapeutic or diagnostic), but also allows the particular characteristics of the selected procedure to be set.

[0062] The selected mode and parameters provided at the user input are provided to a controller 216, which comprises a processor (not shown as part of the controller 216), and a memory (not shown as part of the controller 216), which stores computer-executable instructions (code). In accordance with representative embodiments described more fully below, these instructions, when executed by the processor carry out various functions of representative embodiments described herein. As such, the memory may store a set of software instructions that can be executed to cause the medical system 102 to perform some or all aspects of certain methods or computer-based functions.

[0063] The controller 216 may be implemented by a computer that includes more elements than the controller of Fig. 2B. Notably, in accordance with a representative embodiment, the controller may be remote to the medical system 102, and is adapted to control various aspects of the medical system 102 remotely via connections including both wired and wireless connections and protocols. In this sense, the controller 216, at least in part is a specialty or particular computer useful in controlling the medical system 102.

[0064] The controller 216 may operate as a standalone device or may be connected, for example, using a network to other computer systems or peripheral devices. In representative embodiments, the medical system 102 performs logical processing based on digital signals received via an analog-to-digital converter. The controller 216 can also be implemented as or incorporated intovarious devices, such as a workstation that includes a controller, a stationary computer, a mobile computer, a personal computer (PC), a laptop computer, a tablet computer, or any other machine capable of executing a set of software instructions (sequential or otherwise) that specify actions to be taken by that machine. The controller 216 can be incorporated as or in a device that in turn is in an integrated system that includes additional devices. In an embodiment, the controller 216 can be implemented in a device that also provides video or data communication. Moreover, the controller 216 may be connected to components of the system via a local wired interface such as an Ethernet cable or via a local wireless interface such as a Wi-Fi connection.

[0065] The processor may be considered a representative example of a processor of the controller 216 and executes instructions to implement some or all aspects of methods and processes described herein. The processor is tangible and non-transitory. As used herein, the term “non-transitory” is to be interpreted not as an eternal characteristic of a state, but as a characteristic of a state that will last for a period. The term “non-transitory” specifically disavows fleeting characteristics such as characteristics of a carrier wave or signal or other forms that exist only transitorily in any place at any time. The processor is an article of manufacture and / or a machine component. The processor is configured to execute software instructions to perform functions as described in the various embodiments herein. The processor may be a general-purpose processor or may be part of an application specific integrated circuit (ASIC). The processor may also be a microprocessor, a microcomputer, a processor chip, a controller, a microcontroller, a digital signal processor (DSP), a state machine, or a programmable logic device. The processor may also be a logical circuit, including a programmable gate array (PGA), such as a field programmable gate array (FPGA), or another type of circuit that includes discrete gate and / or transistor logic. The processor may be a central processing unit (CPU), a graphics processing unit (GPU), or both. Additionally, any processor described herein may include multiple processors, parallel processors, or both. Multiple processors may be included in, or coupled to, a single device or multiple devices.

[0066] The term “processor” as used herein encompasses an electronic component able to execute a program or machine executable instruction. References to a processor should be interpreted to include more than one processor or processing core, as in a multi-core processor. A processor may also refer to a collection of processors within a single computer system or distributed among multiple computer systems.

[0067] The memory may include a main memory and / or a static memory, where memories in the medical system 102 communicate with each other and the processor via a bus (not shown). The memory may be considered a representative example of a memory of the controller 216, and store instructions used to implement some or all aspects of methods and processes described herein. Memories described herein are tangible storage mediums for storing data and executable software instructions and are non-transitory during the time software instructions are stored therein. As used herein, the term “non-transitory” is to be interpreted not as an eternal characteristic of a state, but as a characteristic of a state that will last for a period. The term “non- transitory” specifically disavows fleeting characteristics such as characteristics of a carrier wave or signal or other forms that exist only transitorily in any place at any time. The memory is an article of manufacture and / or machine components. The memory is a computer-readable medium from which data and executable software instructions can be read by a computer (e.g., by the processor of the controller 216). The memory may be implemented as one or more of randomaccess memory (RAM), read only memory (ROM), flash memory, electrically programmable read only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, a hard disk, a removable disk, tape, compact disk read only memory (CD- ROM), digital versatile disk (DVD), floppy disk, Blu-ray disk, or any other form of storage medium known in the art. The memory may be volatile or non-volatile, secure and / or encrypted, unsecure and / or unencrypted. The inventive concepts also encompass a computer readable medium that stores instructions that cause a data processing system (such as the DSP of an NV A) to execute the methods described herein. Finally, a computer readable medium is defined herein to be any medium that constitutes patentable subject matter under 35 U.S.C. §101 and excludes any medium that does not constitute patentable subject matter under 35 U.S.C. §101. Examples of such media include non-transitory media such as computer memory devices that store information in a format that is readable by a computer or data processing system. More specific examples of non-transitory media include computer disks and non-volatile memories.

[0068] Additionally, the memory is an example of a computer-readable storage medium. Computer memory is any memory which is directly accessible to a processor. Examples of computer memory include, but are not limited to RAM memory, registers, and register files. References to “memory” should be interpreted as possibly being multiple memories. The memory may for instance be multiple memories within the same computer system. The memorymay also be multiple memories distributed amongst multiple computer systems or computing devices. Software instructions, when executed by the processor, perform one or more steps of the methods and processes as described herein. In an embodiment, the software instructions may reside all or in part within the memory and / or the processor during execution by the controller 216.

[0069] Fig. 3 is a simplified block diagram of front-end and back-end electronics 322 used in A- line imaging in a medical system in accordance with a representative embodiment. Notably, Fig. 3 provides further detail of the receivers 122, 222 described above. The front-end and back-end electronics 322 are connected to a transducer 334, such as transducers 134, 234, and in further detail in connection with various representative embodiments. The front-end and back-end electronics 322 enable not only Doppler flow velocity sensing (blood velocity measurements) and thermal treatment (e.g., tissue ablation and hyperthermia), but also may be used in an imaging mode as described above. Standard A-line (similar as B-mode) imaging can be done to create an M-mode-like image. This generates a rudimentary image that shows the tissue in front of the catheter 136, 236. As alluded to above, imaging fosters real-time monitoring without a catheter exchange. For example, when ablating tissue, imaging enables checking the tissue type in-front of the catheter to prevent ablating undesired locations. For example, it can avoid penetrating the vessel wall. This can be particularly beneficial when using the medical device to cross a total occlusion, for example in-stent thrombosis. This ability of the medical devices of the present teachings to switch from therapeutic mode to imaging mode without a catheter exchange, and using the same transducer for both the imaging and treatment provides a clear improvement to the field of medicine.

[0070] The front-end and back-end electronics 322 comprise a front-end subsystem 301, which is connected to the transducer 334, and a back-end subsystem 303. The front-end subsystem 301 typically comprises a beam former 302, a time gain compensation device 304, and a radio frequency (RF) modulator / demodulator 306. The components of the front-end subsystem 301 are known to one of ordinary skill in the art of US imaging. Notably, the various components of front-end and back-end electronics 322 are common components for Doppler and (A-line) imaging modalities, and can be realized in software and hardware. As such, the various components shown in Fig. 3 are known to those of ordinary skill in the art, and may include elements typically used in image processing elements, such as for Doppler imaging.

[0071] The back-end subsystem 303 comprises an envelope detection stage 308, a dynamic range compression stage 310, a signal filtering stage (e.g., axial / lateral filtering in case of imaging modality, and bandpass filtering for Doppler) 312, a persistence processing stage 314 (when applicable), a scan conversion stage 315 that is image modality specific, a gamma correction stage 316, and is output to a display 312. The components of the back-end subsystem 303 are known to one of ordinary skill in the art of US imaging. Again, like the components noted above, the various components are known elements of the back-end system, which may have specific details and realizations, and are mostly realized through the software implementation, adapted to cause the processor to carry out the various functions.

[0072] Fig. 4A is a conceptual view of a medical device 430 deployed for treatment of a patient in accordance with a representative embodiment. Various aspects and details of the medical device 430 are common to those described above in connection with Figs. 1 A-2B and may not be repeated in order to avoid obscuring the presently described representative embodiments. Moreover, further aspects and details of the medical device 430 are described in connection with the representative embodiments described in connection with Figs. 5-12 below.

[0073] The medical device 430 is disposed in a vessel 432 through which fluid (e.g., blood) flows as shown. The medical device 430 comprises a transducer 434, which is illustratively a ring transducer. The medical device 430 comprises a catheter 436, which is adapted to receive a guidewire 438. As described more fully below, in certain representative embodiments, the guidewire 438 is not disposed in the catheter 436 during use of the medical device 430, whereas in other representative embodiments, the guidewire 438 is disposed in the catheter. Notably, the guidewire can be inserted and removed from the catheter to enable various functions of the medical device 430 to be carried out.

[0074] Fig. 4B is a close-up view of the portions of the medical device 430 of Fig. 4A in accordance with a representative embodiment. Specifically, the transducer 434 is shown disposed at or near a distal end 404 of the catheter 436. The transducer 434 is adapted to emit and receive ultrasound waves to treat tissue and / or measure blood velocity and / or image tissue with the same transducer.

[0075] In an illustrative embodiment, the transducer 434 is a ring transducer disposed in a housing (e.g., stainless steel) (not shown) and embedded in an epoxy (e.g. masterbond) (not shown). Notably, the front and the back of the transducer 434 are connected to an electrical leadto connect the transducer to the medical device 430 (e.g., via the connector 106 in Fig. IB or the PIM 208 in Fig. 2B).

[0076] The catheter 436 comprises a lumen 406 comprising a distal end 407 and a proximal end (e.g., at the point of insertion of the guidewire 438 shown in Fig. 4A). Notably, the lumen 406 can be throughout the catheter (Over-The-Wire - OTW) or can be of the rapid exchange (Rx) type with a side hole (not shown) such that the guide wire in only inside the catheter at the tip side.

[0077] As described more fully below, in addition to providing a conduit for inserting and withdrawing the guidewire 438, the lumen 406 provides a conduit for the introduction of fluids, which may be useful during a procedure using the medical device. Furthermore, and as described more fully below, the presence and absence of the guidewire 438 in the lumen results in difference focal points, beam shapes and intensity of the ultrasound waves generated by the transducer 434. Beneficially, therefore, the medical device 430 can provide different US beams depending on a desired function through the insertion and withdrawal of the guidewire 438, but using the same transducer and without exchanging the catheter 436.

[0078] Notably, the transducer 434 is disposed at or near a distal end 404 of the catheter 436. Depending on the application, “near the distal end” has different meanings. Just by way of illustration, in applications in which the medical device 430 is used for tissue ablation, as used herein, “near the distal end” means the transducer can be located on the catheter 436 up to approximately 10 mm away from the distal end 404 or preferably up to 5 mm from the distal end 404. In illustrative embodiments in which the medical device 430 is used for hyperthermia, or in combination with microbubbles and diagnostic (e.g., Doppler imaging) mode, “near the distal end” means the transducer the transducer 434 can be located on the catheter 436 up to approximately 100 mm away from the distal end 404 or preferably up to 50 mm from the distal end 404. Specifically, in accordance with various representative embodiments, the transducer 434 comprises a ring transducer disposed at or near the distal end of the catheter 436 as shown, with the ring transducer having an inner radius that is substantially the same dimension as an inner radius of the catheter 436 (and the lumen 406) and an outer radius having substantially the same dimension as an outer radius of the catheter 436. Alternatively, the transducer 434 comprises a ring transducer near the distal end of the catheter 436 with ring transducer having an inner radius substantially the same dimension as the outer radius of the catheter 436.

[0079] As noted above, in accordance with various representative embodiments, the transducer 434 comprises a ring transducer. In accordance with various representative embodiments, the ring transducer comprises a piezoelectric element. The piezoelectric element made comprise lead zirconium titanate (PZT), capacitive micromachined ultrasonic transducer (CMUT) and a single crystal piezoelectric material. Notably, each of these materials for the transducer 434 has benefits and drawbacks, and the type of material is selected with these factors in consideration. For example, PZT is easier to form into a ring-shaped structure, whereas single crystal piezoelectric materials have to be cleaved along crystalline planes for proper operation, which can hinder their ease of manufacture into a ring transducer.

[0080] One other potential issue when using PZT for the ring transducer relates to heating. Specifically, in certain representative embodiments described below, it is useful to focus the US beam comparatively close (e.g., 1 mm) from the transducer 434 disposed at or near the distal end of the catheter. This can cause heating of the PZT and via electrodes providing the electrical connections to the transducer 434. Ultimately this heating can impact the wavelength of the US waves being emitted, and thus the performance of the diagnostic and / or therapeutic procedure being performed. In order to mitigate if not prevent runaway due to heating, in certain representative embodiments, the duty cycle of the transmitters 118, 218 are controlled (e.g., shortened). Alternatively, or additionally, in accordance with certain representative embodiments, a cooling fluid may be provided via the lumen 406 to help control heating of the transducer 434 to mitigate or eliminate this heating as well.

[0081] Use of CMUT for the ring transducer is beneficial because of ease of manufacture. Specifically, the ring transducer can be made of a single or plurality of CMUT elements disposed over the distal end of the catheter 436. In addition, the electrical impedance of CMUT ring transducers is low compared to the that of PZT, and results in less complex electronics required for driving the ring transducer and less susceptibility to heating. Furthermore, the acoustic impedance of a CMUT ring transducer is better-matched to the fluid (blood) in the vessel 432, resulting in improved performance as well.

[0082] Finally, while single crystal piezoelectric materials such as lead titanate, zirconium titanate and barium titanate are contemplated for use in the ring transducer, as noted above, the need to cleave the material along defined crystalline planes renders the yield and cost high compared to PZT or CMUT based ring transducers. 1

[0083] Fig. 4C is a perspective view in partial cross-section the transducer 434 of the medical device 430 in accordance with another representative embodiment. A piezoelectric element 408 is disposed over a backing layer 410 and beneath a matching layer 412. The backing layer 410 beneficially dampens the acoustic waves transmitted to the back side and reduces the transmittance of the waves via the piezoelectric element 408 back to the receiver 122, 222 (not shown in Fig. 4C), and thereby improves the overall performance of the medical device 430. Just by way of example, the backing layer 410 may comprise particle- filled epoxies or foam-like materials within the purview of one of ordinary skill in the art, and having a thickness of approximately 0.05 mm to approximately 10 mm. The matching layer 412 improves the acoustic impedance matching of the piezoelectric material to the fluid in the vessel 432. In accordance with a representative embodiment, the matching layer comprises a layer of suitable epoxy approximately 30pm thick. Just by way of example, the matching layer 412 may comprise epoxies, particle filled epoxy (e.g., graphite-filled epoxy), rubber like materials, Teflon and similar materials within the purview of one of ordinary skill in the art . The thickness of the matching layer is selected according to the frequency of the US waves and the particular material selected for the matching layer. Illustratively, the matching layer 412 incorporating these illustrative materials has a thickness in the range of approximately 20 pm to approximately 80 pm.

[0084] Fig. 5A is a perspective view in partial cross-section a transducer 534 of a medical device in accordance showing excitation of transducer elements in accordance with a representative embodiment. Various aspects and details of the transducer 534 of the representative embodiments are common to those described in connection with Figs. 1 A-4C. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0085] The transducer 534 comprises a piezoelectric element 508 is disposed over a backing layer 510 and beneath a matching layer 512. As noted above, the backing layer 510 beneficially reduces transmittance of mechanical waves from the piezoelectric element 508 back the receiver 122, 222 (not shown in Fig. 5 A), and thereby improves the overall performance of the medical device comprising the transducer 534. As noted above, the matching layer 512 improves the acoustic impedance matching of the piezoelectric material to the fluid in the vessel (e.g. vessels 142, 242, 342 and 432).

[0086] Notably, in accordance with a representative embodiment, the transducer 534 has a width of approximately 100 pm and a thickness of approximately 100 pm. In accordance with various representative embodiments, the transducer 534 has a thickness in a range of approximately 50 pm to approximately 500 pm and a thickness of approximately 50 pm to approximately 500 pm. In still other representative embodiments, the transducer 534 has a thickness in a range of approximately 50 pm to approximately 300 pm and a thickness of approximately 50 pm to approximately 300 pm.

[0087] Vibration of the transducer 534 is shown at 540, and the damping of acoustic waves is shown at 542, where it can be seen that the waves generated extended into the backing layer 510 to a point, but not through the thickness of the backing layer 510 not to allow acoustic energy to return to the receiver (not shown in Fig. 5A).

[0088] Fig. 5B is a graph of acoustic pressure (Pa) versus frequency (MHz) of the transducer 534 in accordance with a representative embodiment. As shown, the transducer 534 has dimensions and material selected to provide a resonance peak 544 of approximately 1.85 x 105Pa at approximately 12 MHz. Notably, this operational frequency is often selected for Doppler flow sensing. Notably, the total acoustic absolute pressure shown in Fig. 5B at is at a distance of 5 mm from the distal end of the transducer 534 when 10 V is applied.

[0089] As described above, the transducer 534 is adapted to function in two operational modes without the need to exchange the catheter of the medical device at or near the distal end of the catheter. The device can be operated in two modes.

[0090] In a first operational mode, the medical device comprising transducer 534 does not have a guidewire disposed in the lumen of the catheter (not shown in Fig. 5A). In this mode of operation, the medical device comprising transducer 534 creates a focal point of the US waves in a region in front of the transducer, and comparatively close (e.g., approximately 0.5 mm to approximately 10 mm to the end of the transducer 534 (see also Figs 6A-6B, and their attendant descriptions below). Notably, the guidewire (not shown in Fig. 5A) is used to move the medical device comprising the transducer 534 to a point where a thermal procedure (e.g., ablation of tissue) is desired. After the medical device is properly positioned, the guidewire is withdrawn back into the catheter lumen and the thermal procedure is carried out based on input to the user input of the console as described more fully above. As alluded to above, before the therapeutic ultrasound procedure is carried out, the transducer 534 may be switched to an imaging mode todetermine where to move the medical device to carry out properly the desired procedure (e.g., moved proximate to a lesion to be ablated, and not proximate to tissue that is not to be ablated). Moreover, after the medical device is moved to the desired location, the transducer 534 may be in an imaging mode to make confirm the proper positioning of the medical device to carry out the ultrasound treatment. After the ultrasound treatment is completed, the transducer 534 can again be switched to an imaging mode, to determine if the ultrasound treatment was successful, or if another treatment is required. As will be appreciated, because the same transducer is used for both the imaging and ultrasound treatment procedures, a catheter exchange is not required, and not only is the procedure streamlined, but also less expensive in terms of needed equipment and clinician time. Finally, in accordance with a representative embodiment, it is noted that switching between different modes can be carried out intermittently, for example, before a treatment is completed, such as for monitoring the progression of the treatment.

[0091] In a second mode of operation, the medical device comprising transducer 534 has a guidewire disposed in the lumen of the catheter (not shown in Fig. 5A). In this mode the guidewire extends from the distal end of the lumen of the catheter. In this position, the guide wire is effectively blocking the center where the US focusses when the guide wire is not extending past the distal end of the catheter. In this mode of operation, the medical device comprising transducer 534 creates a US beam, which compared to the US beam created without the guidewire disposed in the lumen, is comparatively wide and its energy is less focused. In this mode of operation, the medical device operates in a flow sensing mode. As such, after locating the guidewire in the catheter, the clinician can set the transducer to a flow sensing mode as described above, and a flow sensing (e.g., fluid (blood) velocity measurement) procedure can be carried out. Moreover, while the acoustic power provided in this configuration is not great enough to carry out many thermal procedures (e.g., tissue ablation), sufficient acoustic power is transmitted to the vessel for moderate heating tissue or to generate cavitation effects using microbubbles that can be used in a medical procedure. In accordance with a representative embodiment, the microbubbles may be infused to destroy the tissue via the cavitation effect. This therapeutic embodiment can also work in combination with the configuration with the guidewire in place. Alternatively, or in addition to the thermal / cavitation effects the therapeutic ultrasound mode could be used to deliver drug-loaded microbubbles via the lumen 506 to achieve the desired therapeutic effect.

[0092] As alluded to above, in one illustrative example, after an ablation procedure is completed, the medical device can again be switched to flow sensing mode (e.g., via the user input) and inserting the guidewire to measure the flow (e.g., blood velocity) to gauge the effectiveness of the ablation step. Again, switching from a thermal procedure to a flow sensing procedure can be done without a catheter exchange, and using the same transducer 534. As will be appreciated, because the same transducer is used for both the imaging and flow sensing procedures, and the catheter exchange is not required, not only is the procedure streamlined, but also less expensive in terms of needed equipment and clinician time.

[0093] Fig. 6A shows an acoustic pressure (Pa) profile of a medical device without a guide wire disposed in a catheter in accordance with another representative embodiment. Various aspects and details of the transducer 634 of the representative embodiments are common to those described in connection with Figs. 1 A-5B. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0094] As shown in Fig. 6 A, a focal point 602 of the ultrasound beam is comparatively close to the distal end of the transducer 634, and provides sufficient power to carry out the desired thermal procedure.

[0095] Fig. 6B shows a temperature profile (°C) of the medical device in accordance with a representative embodiment. Notably, the temperature of the tissue reaches a level greater than 62.5° and thereby provides sufficient heat to carry out the desired thermal procedure (e.g., tissue ablation). Additionally, the temperature can be increased by increasing the driving voltage.

[0096] Fig. 7A shows an acoustic profile (Pa) versus angle and distance of a transducer of a medical device in accordance with a representative embodiment. Various aspects and details of the transducer 734 of the representative embodiments are common to those described in connection with Figs. 1 A-6B. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0097] In the representative embodiment, the medical device is set for an imaging procedure. As shown, the US beam 704 has lobes at various angles, but has its greatest energy at 702 directly above (or in front) of the transducer 734 at 0°. Moreover, the US beam 704 provides images in first, second and third regions 706, 708 and 710.

[0098] Fig. 7B shows A-line image generation of a transducer of a medical device with US beam 704 as located as shown in Fig. 7A. In this embodiment, the x-axis is the time axis. Specifically,Fig. 7B shows an A-line image showing reflected intensities at a first region 706 (blood at approximately 0.0 to approximately 5 mm from the distal end of the catheter), second region (thrombus at approximately 5 mm to 10 mm from the distal end of the catheter) and third region (blood at approximately 10 mm to 15 mm from the distal end of the catheter.

[0099] Fig. 8A is a perspective view in partial cross-section a transducer 834 of a medical device in accordance showing excitation of transducer elements in accordance with a representative embodiment. Various aspects and details of the transducer 834 of the representative embodiments are common to those described in connection with Figs. 1 A-7B. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0100] The transducer 834 comprises three concentric piezoelectric elements 803, 804, 805 to form concentric ring transducers disposed over a backing layer 810 and beneath a matching layer 812. As noted above, the backing layer 810 beneficially reduces transmittance of mechanical waves from the piezoelectric three concentric piezoelectric elements 803, 804, 805 back the receiver 122, 222 (not shown in Fig. 8A), and thereby improves the overall performance of the medical device comprising the transducer 834. As noted above, the matching layer 812 improves the acoustic impedance matching of the piezoelectric material to the fluid in the vessel (e.g. vessels 142, 242, 342 and 432).

[0101] Vibration of the transducer 834 is shown at 840, and the damping of acoustic waves is shown at 842, where it can be seen that the waves generated extended into the backing layer 510 to a point, but not through the thickness of the backing layer 810 not to allow acoustic energy to return to the receiver (not shown in Fig. 8A).

[0102] Notably, in accordance with a representative embodiment, each of the piezoelectric elements 803, 804 and 805 have a width of approximately 100 pm and a thickness of approximately 100 pm. In accordance with various representative embodiments each of the piezoelectric elements 803, 804 and 805 has a thickness in a range of approximately 50 pm to approximately 500 pm and a thickness of approximately 50 pm to approximately 500 pm. In still other representative embodiments, the each of the piezoelectric elements 803, 804 and 805 has a thickness in a range of approximately 50 pm to approximately 300 pm and a thickness of approximately 50 pm to approximately 300 pm.

[0103] Fig. 8B is a graph of acoustic pressure (Pa) versus frequency (MHz) of the transducer 834 in accordance with a representative embodiment. As shown, the transducer 834 has dimensions and material selected to provide a resonance peak 844 of approximately 6.7 x 105Pa at approximately 12 MHz. As will be appreciated from a comparison of the acoustic power provided by the transducer 534, the use of three concentric piezoelectric elements 803, 804, 805 significantly not only acoustic power provided by the transducer 834, but also increases sensitivity of the transducer 834 in receiving the US signals reflected from the subject. Ultimately, this results in greater capabilities when carrying out an ultrasound-based treatment, but also improves the resolution of the images when the transducer 834 is in an imaging mode.

[0104] Furthermore, the use of multiple concentric piezoelectric elements enables beam steering through control of the individual piezoelectric elements. In accordance with a representative embodiment, two or three concentric (ring) piezoelectric elements can be disposed in the catheter. To effect steering, a time delay is applied to each of the piezoelectric elements, resulting in a US beam focused at a certain distance from the distal end of the catheter. The clinician can select a distance (e.g., at the user input of the console or the GUI) for the region of interest (ROI). Based on these inputs, the processor executes instructions to calculate the necessary time delays, based on the distance to focal point (ROI) and mutual arrangement of the rings. Fig. 9A is a perspective view in partial cross-section a transducer 934 of a medical device in accordance showing excitation of transducer elements in accordance with a representative embodiment. Various aspects and details of the transducer 934 of the representative embodiments are common to those described in connection with Figs. 1 A-4C. These common aspects and details may not be repeated to avoid obscuring the presently described representative embodiments.

[0105] The transducer 934 comprises a piezoelectric element 908 is disposed over a backing layer 910 and beneath a matching layer 912. As noted above, the backing layer 910 beneficially dampens the acoustic waves transmitted to the back side and reduces transmittance of waves via the piezoelectric element 908 back to the receiver 122, 222 (not shown in Fig. 9A), and thereby improves the overall performance of the medical device comprising the transducer 934. As noted above, the matching layer 912 improves the acoustic impedance matching of the piezoelectric material to the fluid in the vessel (e.g. vessels 142, 242, 342 and 432).

[0106] Vibration of the transducer 934 is shown at 940, and the damping of acoustic waves isshown at 942, where it can be seen that the waves generated extended into the backing layer 910 to a point, but not through the thickness of the backing layer 910 to allow acoustic energy to return to the receiver (not shown in Fig. 9A).

[0107] In the presently described representative embodiment, the dimensions of the piezoelectric element 908 of the ring transducer are chosen such that there are multiple resonance frequencies. Providing multiple resonance frequencies enables switching between the frequencies and hence changing the focal point depth and intensity of the ultrasound beam in therapy. Moreover, for Doppler flow sensing the signal strength and penetration depth can also be adjusted by changing the driving frequency. For imaging the resolution and penetration depth can be adjusted in a similar way.

[0108] Notably, in accordance with a representative embodiment, the transducer 934 has a width of approximately 280 pm and a thickness of approximately 100 pm. In accordance with various representative embodiments, the transducer 934 has a thickness in a range of approximately 50 pm to approximately 500 pm and a thickness of approximately 50 pm to approximately 500 pm. In still other representative embodiments, the transducer 934 has a thickness in a range of approximately 50 pm to approximately 300 pm and a thickness of approximately 50 pm to approximately 300 pm.

[0109] Fig. 9B is a graph of acoustic pressure (Pa) versus frequency (MHz) of the transducer 934 in accordance with a representative embodiment. As shown, the transducer 934 has dimensions and material selected to provide resonance peaks 922, 924, 926 and 928. These resonance peaks are at different frequencies and thereby can be used to select the depth of a thermal treatment, with the higher frequency resonance modes being used to increase the focal depth of the ultrasound. Moreover, as noted above, increased frequency can provide improved resolution when the transducer 934 is used in imaging mode.

[0110] Fig. 10 is a cross-sectional view of a medical device 1030 comprising a ring transducer and an acoustically transparent element 1040 disposed at a distal end of the transducer in accordance with a representative embodiment. Various aspects and details of the medical device 1030 are common to those described in connection with the representative embodiments of Figs. 1 A-9B. These common aspects and details may not be repeated to avoid obscuring the description of the presently described representative embodiment.

[0111] The medical device 1030 is disposed in a vessel 1032 through which fluid (e.g., blood)flows as shown. The medical device 1030 comprises a transducer 1034, which is illustratively a ring transducer. The medical device 1030 comprises a catheter 1036, which is adapted to receive a guidewire 1038. As described more fully above, in certain representative embodiments, the guidewire 1038 is not disposed in the catheter 1036 during use of the medical device 1030, whereas in other representative embodiments, the guidewire 1038 is disposed in the catheter. Notably, the guidewire can be inserted and removed from the catheter to enable various functions of the medical device 1030 to be carried out. Notably, and as described more fully above, the transducer 1034 is disposed at or near a distal end 1004 of the catheter 1036. In the present illustrative embodiment, the acoustically transparent element 1040 is disposed at the distal end of the transducer 1034.

[0112] The acoustically transparent element 1040 has acoustic properties substantively identical to those of blood and tissue. The acoustically transparent element enables ultrasound waves to be transmitted through the tip of the element. The tip of the acoustically transparent element is tapered as shown. Among other benefits, the tapered tip fosters less resistive navigation of the medical device 1030 through tight lesions and may be less traumatic to the vessel wall.

[0113] The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of the disclosure described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

[0114] One or more embodiments of the disclosure may be referred to herein, individually and / or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purposemay be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the description.

[0115] The Abstract of the Disclosure is provided to comply with 37 C.F.R. § 1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

[0116] The preceding description of the disclosed embodiments is provided to enable any person skilled in the art to practice the concepts described in the present disclosure. As such, the above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents and shall not be restricted or limited by the foregoing detailed description.

Claims

CLAIMS:

1. A medical device (1030), comprising: a catheter (1036) body comprising a lumen (406) comprising a distal end (1004) and a proximal end; and a transducer (1034) disposed at or near the distal end (1004) of the catheter (1036) body, the transducer (1034) being adapted to emit ultrasound waves to treat tissue and / or emit and receive ultrasound waves measure blood velocity and / or image tissue with the same transducer (1034).

2. The medical device (1030) of claim 1, wherein the treatment of the tissue comprises one of ablation, cavitation, cauterization and hyperthermia.

3. The medical device (1030) of claim 1, wherein the transducer (1034) comprises a ring transducer (1034) disposed around a perimeter of the distal end (1004) of the catheter (1036) body.

4. The medical device (1030) of claim 3, wherein the ring transducer (1034) is one of lead zirconium titanate (PZT) piezoelectric transducer (1034), a single crystal piezoelectric transducer (1034), and a capacitive micromachined ultrasonic (CMUT) transducer (1034).

5. The medical device (1030) of claim 3, wherein the ring transducer (1034) comprises a piezoelectric element (408) disposed in a housing, and comprises an acoustic impedance matching layer (412) disposed at a distal end (1004) of the transducer (1034), and a backing layer (410) disposed at a proximal end of the transducer (1034) and connected to the distal end (1004) of the catheter (1036) body.

6. The medical device (1030) of claim 1, further comprising a guidewire (1038) disposed in the lumen (406) during the measurement of the blood velocity.

7. The medical device (1030) of claim 1, further comprising a guidewire (1038) disposed in the lumen (406) extending from the catheter (1036) body and the measure of the blood velocity comprises Doppler flow velocity mode.

8. The medical device (1030) of claim 6, wherein the guidewire (1038) is steerable.

9. The medical device (1030) of claim 1, wherein a guidewire (1038) is not extending from the catheter (1036) body during the treatment of the tissue.

10. The medical device (1030) of claim 3, wherein the ring transducer (1034) comprises a plurality of concentric piezoelectric ring elements.

11. The medical device (1030) of claim 10, wherein the plurality of concentric piezoelectric ring elements is adapted to steer an ultrasound beam (704) through time delay excitation of the concentric piezoelectric ring elements.

12. The medical device (1030) of claim 1, wherein a cooling fluid is provided in the lumen (406) to cool the transducer (1034) or to allow the treatment of the tissue to be deeper within the tissue.

13. The medical device (1030) of claim 1, wherein a fluid is provided in the lumen (406) to enhance treatment by thrombolytics or microbubbles.

14. The medical device (1030) of claim 1, wherein when the transducer (1034) is near the distal end (1004) of the lumen (406), and the medical device (1030) further comprises an acoustically transparent element (1040) disposed at a distal end (1004) of the transducer (1034).

15. The medical device (1030) of claim 14, wherein the acoustically transparent element (1040) tapers toward a distal end (1004) of the catheter (1036) body.

16. The medical device (1030) of claim 3, wherein the ring transducer (1034) is adapted to generate a plurality of resonance frequencies.

17. The medical device (1030) of claim 16, wherein each of the plurality of resonance frequencies is selected to perform to treat the tissue, measure the blood velocity or capture the image.

18. A method of carrying out a medical procedure, the method comprising: providing a catheter (1036) body comprising a lumen (406) comprising a distal end (1004) and a proximal end; providing a transducer (1034) disposed at or near the distal end (1004) of the catheter (1036) body; and emitting and receiving ultrasound waves to treat tissue and / or measure blood velocity and / or image tissue with the same transducer (1034).

19. The method of claim 18, wherein the transducer (1034) comprises a ring transducer (1034) disposed around a perimeter of the distal end (1004) of the catheter (1036) body.

20. The method of claim 18, wherein the treatment of the tissue comprises one of ablation, cavitation, cauterization and hyperthermia.

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