Wireless intravascular ultrasound imaging systems and methods

Abstract

Wireless IVUS systems and methods are disclosed with an IVUS catheter having a distal tip micropulser enabling lower power, higher fidelity imaging in a wireless patient interface module (PIM).

Description

WIRELESS INTRAVASCULAR ULTRASOUND IMAGING SYSTEMS AND METHODSRELATED APPLICATIONS

[0001] This application claims the benefit of priority of U. S. Provisional Patent Application Serial No. 63 / 689,325, filed on August 30, 2024, and titled “Wireless Intravascular Ultrasound Imaging Systems and Methods”; U.S. Provisional Patent Application Serial No. 63 / 689,431, filed on August 30, 2024, and titled “Systems and Methods For Detecting Broadband Frequencies in Intravascular Ultrasound”; and U.S. Provisional Patent Application Serial No. 63 / 696,222, filed on September 18, 2024, and titled “Systems and Methods for Image Enhancement of Intravascular Ultrasound Data”; each of which application is incorporated by reference herein in its entirety.

[0002] International Application No. PCT / US2024 / 023370, filed on April 5, 2024, entitled “Systems and Methods for Generating an Accurate Ultrasonic Impulse for a Hi h -Resolution Ultrasonic Imaging Catheter” is related to this application, and is incorporated by reference herein in its entirety.FIELD OF THE DISCLOSURE

[0003] The present disclosure relates to intravascular ultrasound (IVUS) and, more specifically, to systems and methods for wireless IVUS imaging.BACKGROUND

[0004] Intravascular ultrasound (IVUS) is an imaging method for assessment of vascular pathologies and the guidance of vascular interventions. IVUS is of particular value to coronary percutaneous interventions (PCI) where assessment of plaques and procedural guidance can be difficult when utilizing coronary angiography alone. Coronary IVUS was first made commercially available in the early 1990s. The technology has expectedly steadily improved, and substantial clinical evidence for the benefit of IVUS for PCI has accumulated. The additional imaging information provided by IVUS, such as identification of the presence and extent of plaque, more accurate vessel sizing, measurement of the external elastic membrane (EEM), and assessment of stent deployment has the potential to improve the safety of stenting, including optimization of length of vessel to stent, selection of stent landing zones, and identification of lesions at higher risk of distal embolization during stenting.

[0005] The proven ability of IVUS to identify high risk lesions can also facilitate implementation of strategies to prevent future coronary events. Clinical studies have shown that treatment decisions1 Attorney Docket No. 19275-005WOU1for individual patients are complex and often surrounded by uncertainty. The clinician is faced daily with challenging decisions regarding revascularization strategies (e.g., PCI versus bypass surgery) and important procedural issues regarding the likelihood of success of PCI (e.g., identification of which lesions to treat, length of vessel to treat, optimal stent deployment, risk of distal embolization and periprocedural myocardial infarction (MI), etc.). While the overwhelming majority of PCI cases in the US are performed only under angiographic guidance, coronary angiography alone in many clinical situations fails to provide adequate information for such complex decisions.

[0006] IVUS imaging was developed for more accurate and detailed assessment of vascular pathologies compared to angiography alone. With IVUS, a physician can confirm the presence of plaque, as opposed to stenosis alone, and the physician can visualize detailed structural information about the plaque, such as plaque burden, plaque eccentricity, extent of vascular remodeling, and limited aspects of composition. In addition, the physician can use the detailed structural information for guidance of numerous aspects of the PCI procedure, such as confirmation of adequate stenosis to warrant a treatment such as stenting, measurement of lesion length for proper sizing of stents or balloons, measurement of the external elastic membrane for careful planning of balloon or stent expansion, or determination of starting and ending landing zones for a stent. Despite the unequivocal benefits of IVUS, usage in many major geographies, including the US, is below 20% of cases due in large part to IVUS systems being expensive and difficult to use.

[0007] There are two basic types of commercially available IVUS catheters - catheters with a single transducer element and a rotating and retractable core, and catheters with a multiplexed array of transducers at the tip. In both cases, the catheter must be plugged into a wired connection to an interface unit that handles data transfer over a wire to an image processing and display system (often a free-standing console).

[0008] In the case of single-transducer rotating core catheters, the interface unit must also handle high speed rotation and pullback of the catheter core, since rotation is necessary to achieve a cross- sectional image (usually 1800RPM or 30 frames per second) and pullback is necessary to achieve a volumetric image. Pullback information is conveyed to the console and image processing and display unit via a wired connection between the motor drive unit and the console. Commercially available interface units are bulky and heavy, since they must contain motors for both rotation and pullback, they must accommodate the physical movement of a carriage over the maximum pullback distance (usually 150mm), they have not been designed with modem microelectronics, and they must have a2 Attorney Docket No. 19275-005WOU1sturdy and rigid frame to contain all the components. The bulky, wired units are usually placed on the catheterization lab table next to, or even on top of, the patient’ s legs and the unit itself or the cord often gets in the way of other procedural activities and equipment. Being wired to line power also introduces noise from the facility’s power systems.

[0009] In the case of catheters with a multiplexed array of transducers at the tip (“Phased array” catheters), the image is produced by executing a sequence of excitation and detection with the circularly-arranged transducers to create a virtual rotation and corresponding frame. Volumetric images can be obtained by retracting the entire catheter from the vessel while continuing to acquire frames. Generally available commercial interface modules for phased array catheters tend to be large, based on older electronic architectures, and also require a wired to line power.

[0010] In both types of IVUS systems, the units are required to have a sterile barrier to be used in the sterile field. Since the units are wired, these single-use sterile barriers are open on one end as a plastic sleeve and utilize a long, telescoping design to cover a significant length of the cord back to the console (or other integrated control room arrangement). The plastic sleeve is inserted over the probe and the cable and extends off the sterile field. Once the plastic sleeve is out of the sterile field, then cable can be attached to the non-sterile console. Because of the size of the sterile barrier and unrolling procedure, bagging the interface unit usually takes two people - one in and one out of the sterile field. It can be a cumbersome and time-consuming procedure.

[0011] In spite of a recognized need in the art for wireless systems, the state of the art for IVUS remains wired systems due primarily to the large amount of data that must be collected and processed during an IVUS procedure and the power requirements for generating the ultrasound pulses. The data requirements with conventional IVUS imaging catheters can be on the order of 300 Mbps to 1 Gbps. Power requirements may be in the range of 1000VA. Because of these requirements, “current catheter imaging is based on wired communications [even though] the use of wired communications can complicate the physician’s task due to the high number of cables in his work area, which can even reduce the quality and the results of the procedure, not to mention possible sterilization problems. In that context, the use of wireless communications would be greatly preferable.” But, notwithstanding this clear preference, “[t]he design of wireless communications is very challenging, especially in applications such as catheter imaging, where it is important to combine very high data rates with low latencies.” Guerreiro et al., On the Achievable Capacity of MIMO-OFDM Systems in the CathLab Environment, Sensors 2020, 20, 938; doi: 10.3390 / s20030938.3 Atorney Docket No. 19275-005WOU1

[0012] Without intending to be bound by theory, the present inventors believe there are a number of identifiable reasons that the need for wireless IVUS systems remains unmet. First, the nature of gigahertz-level sample rates is inherently complex. A system capable of handling such high sample rates requires significant power and large circuitry, which is not practical for a handheld device. Beyond the circuit size, storing and supplying sufficient portable power would demand an oversized battery pack — again, not compatible with a portable form factor. Second, there are limitations in wireless communication. A gigasample data rate generates roughly two gigabytes of data per second during operation. Even with typical lossless compression — often around 2:1 — the system would still need to handle about one gigabyte of continuous data streaming per second. Currently, only Wi-Fi 7 (802.11be) is theoretically capable of supporting such throughput under ideal conditions. However, the protocol is brand new, with many vendors yet to release solutions, and in practice, reliably sustaining this data rate is not yet feasible. Further, the power consumption required for such a system is far beyond what a handheld device can reasonably support with pre-existing technology.

[0013] IVUS imaging was developed for more accurate and detailed assessment of vascular pathologies compared to angiography alone and provides many significant diagnostic advantages over other imaging techniques. However, in spite of the unequivocal benefits of IVUS, usage in many major geographies, including the US, is below 20% of cases due in large part to IVUS systems being expensive and difficult to use. Wireless system embodiments disclosed herein are proposed to facilitate use of IVUS with a goal of increasing its beneficial use for patients in need of more accurate assessment of vascular disease.SUMMARY OF THE DISCLOSURE

[0014] In one implementation, the present disclosure is directed to a wireless intravascular ultrasound (IVUS) imaging system. The system includes an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; and a patient interface module (P1M) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM wireless transceiver and the distal tip micropulser, and a battery configured to power the PIM and the distal tip micropulser, wherein the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission and the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal.4 Atorney Docket No. 19275-005WOU1

[0015] In another implementation, the present disclosure is directed to an angiography system including IVUS imaging. The system includes an angiography table; an external patient imaging system; an angiography console including a display configured to present images from the external patient imaging system and IVUS imaging, a wireless transceiver and an IVUS server; an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; a patient interface module (PIM) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM wireless transceiver and the distal tip micropulser, a battery configured to power the PIM and the distal tip micropulser and an inductive power coupling coil for remotely charging the battery, wherein the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission and the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal to wireless transceiver of the angiography console; and an inductive power coupling pad including a power coupling coil disposed on or integrated into the angiography table.

[0016] In yet another implementation, the present disclosure is directed to a wireless intravascular ultrasound (IVUS) imaging system. The system includes an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; a catheter supply rail extending though the IVUS catheter to provide power to the distal tip microcontroller; an impulse generator supply rail extending through the IVUS catheter to provide impulse power to the transducer; a patient interface module (PIM) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM wireless transceiver and the distal tip micropulser, and a battery configured to power the PIM and the distal tip micropulser, wherein - the PIM delivers a voltage of about 2 VDC to 5 VDC to the distal tip microcontroller via the catheter supply rail; the Pirn delivers DC power at current levels of up to about 450 mA via the impulse generator supply rail to drive the distal tip transducer; the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission, and the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal; and an external server remote from the PIM, the external server including a server5 Atorney Docket No. 19275-005WOU1wireless transceiver configured to communicate with the PIM wireless transceiver to receive the wirelessly transmitted processed image signal.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For the purpose of illustrating the disclosure, the drawings show aspects of one or more embodiments of the disclosure. However, it should be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:FIG. 1 is an overall perspective view of an embodiment of a wireless IVUS system according to the present disclosure;FIG. 2 is a schematic depiction of an embodiment of an IVUS system with a wireless imaging interface unit according to the present disclosure;FIG. 3 is a schematic depiction of an alternative IVUS system with a wireless imaging interface unit according to the present disclosure;FIG. 4 is a schematic depiction of yet another alternative IVUS handheld system where the A / D board and all other electronics that must be connected to the rotating core are themselves also rotating, and rather than a slip ring, power is supplied to the board inductively, and data is transmitted wirelessly, obviating the need for an electrical slip-ring;FIG. 5 is a schematic diagram depicting a wireless IVUS handheld system according to an embodiment of the present disclosure;FIG. 6 is a schematic diagram depicting a detail view of a wireless IVUS handheld system according to an embodiment of the present disclosure;FIG. 7A is a schematic depiction of an embodiment of a wireless inductive charging system for an IVUS system according to the present disclosure;FIG. 7B is detail view of an embodiment of a wireless inductive charging system for an IVUS system according to the present disclosure;FIG. 8 is a schematic diagram depicting an example of a control architecture for embodiments of Patient Interface Modules (PIM) according to the present disclosure;FIG. 9 is a schematic cross-section of the distal end of an imaging core including a distal tip micropulser according to embodiments of the present disclosure;6 Atorney Docket No. 19275-005WOU1FIG. 10 is a block diagram illustrating primary functional components of distal tip micropulser circuits according to the present disclosure;FIG. 11 is a schematic of one example of a distal tip micropulser circuit according to an embodiment of the present disclosure;FIG. 11A is a schematic of another example of a distal tip micropulser circuit according to an alternative embodiment of the present disclosure;FIG. 12 is a circuit board / block diagram of an embodiment of the micropulser circuit shown in FIG. 11.FIG. 13 is a plot of a single cycle impulse generated with a distal tip micropulser circuit according to the present disclosure, showing an enlarged detail with timing references;FIG. 14 is a plot of a double cycle impulse generated with a distal tip micropulser circuit according to the present disclosure;FIG. 15 is a schematic cross-section of the distal end of an imaging core and sheath according to an alternative embodiment of the present disclosure;FIG. 16 is a schematic cross-section of the distal end of an imaging core and sheath according to another alternative embodiment of the present disclosure;FIG. 17 is a block diagram illustrating an example of a controller; andFIGS.18A-E are a series of graphs showing an example of wavelet transform analysis according to an embodiment of the present disclosure, wherein FIG. 18A is an initial broadband signal generated by the distal micropulser, FIG. 18B depicts approximate coefficients from a low pass filter, FIG. 18C depicts a set of detail coefficients at one wavelet level, FIG. 18D depicts a set of detail coefficients at another wavelet level, and FIG. 18E depicts a further set of detail coefficients at yet another wavelet level.DETAILED DESCRIPTION

[0018] To make IVUS easier to use and increase the usage rates, especially at hospitals with limited staff, the catheter interface units need to be smaller, unwired, easier to bag, and easier to place and move in the sterile field. These objectives can be achieved according to the present disclosure by a catheter interface unit that utilizes battery power for its basic tasks, e.g., IVUS pulsing, possible motor drives, signal buffer and amplification electronics, and transmits data by wireless communication links to an image processing and display unit (e.g., cart-based console or control room7 Atorney Docket No. 19275-005WOU1workstation). Making a smaller, easier to use interface unit can optionally be further facilitated by not providing motorized pullback capability in the interface unit. This removes the necessity of a second motor and its power requirements, it relaxes requirements for the structural integrity and stiffness of the supporting frame, and importantly it eliminates the space required to move a carriage an equal distance as the pullback length provided (usually about 150mm).

[0019] In one embodiment, as illustrated in FIG. 1, an IVUS system 10 according to the present disclosure includes an IVUS catheter 12 with a distal tip micropulser 13 connected to motor drive unit or patient interface module (PIM) 14, which is powered by battery 16 and includes internal controller 17 including or communicating with wireless transceiver 18. More details of embodiments of distal tip micropulser 13 are described below in connection with FIGS. 9-16. Data and power connections between distal tip micropulser 13, internal controller 17 and wireless transceiver 18 may be by wired connections including conductors extending through catheter 12 as further described below. For rotational embodiments, imaging core rotational mechanism 19 is also included. Signals from wireless transceiver 18 are received at external server 20 via wireless transceiver 22. Server 20 may communicate with an external display 24 to display IVUS images in real-time or near real-time. External server 20 also may include computing components such as processor 25 and memory 26, and may be further configured as a controller as described below in connection with FIG. 17. IVUS System 10 may be configured with a separate or standalone angiography system 28 as shown in FIG. 2, which may be conventionally connected with external server 20 by wired connections or may also communicate wirelessly with external server 20. Alternatively, as shown in FIG. 2, server 20 may be replaced by integrated server 27 as part of an angiography suite or system, which includes a display and optional other functionality of the angiography system. Catheter 12 and PIM 14 make up the handheld system components of the overall system 10, which additionally includes at least server 20 and typically also the external display 24 driven by the server. Such a system may also include inductive power coupling for charging PIM 14, including a charging pad position on or integrated into the angiography table as further described below.

[0020] In another embodiment, as illustrated in FIG. 3, IVUS system 30 according to the present disclosure is integrated with an angiography suite and includes IVUS catheter 12 connected with and driven by PIM 14, which again is powered by battery 16 and includes wireless transceiver 18. PIM 14 in this embodiment communicates directly with wireless transceiver 32 of integrated control console 34, which includes the wireless IVUS system server as described above and also provides a8 Atorney Docket No. 19275-005WOU1common control and display for all catheter lab imaging such as an angiography table 36 with integrated X-ray 38 and display 40.

[0021] Wireless systems as disclosed herein leverage a number of advances in IVUS technology developed by the present Applicant in order to provide image quality at least on par with prior wired systems at power levels supportable by battery power sources. One such advance is the use of the micropulser 13 integrated into the IVUS catheter distal tip as disclosed in International Application No. PCT / US2024 / 023370, filed on April 5, 2024, and titled “Systems and Methods for Generating an Accurate Ultrasonic Impulse for a High-Resolution Ultrasonic Imaging Catheter”, which is incorporated herein by reference in its entirety for all purposes. Another advance leveraged in the herein-disclosed wireless embodiments is the incorporation of microcontroller intelligence into the internal processing module of the patient interface module (PIM), which allows the magnitude of data required to be transmitted to the IVUS console to be on a scale which can be transmitted wirelessly and enable the handheld wireless form factor of the PIM.

[0022] By using a distal tip micropulser integrated into the IVUS catheter tip as shown in FIGS. 9-16, described below in connection with those figures, and in more detail in the foregoing incorporated International Application, the PIM requires significantly less power to facilitate wireless operation. Unlike conventional systems, where the pulse is generated at the IVUS processing unit and then travels along the system to the catheter tip, the proximity of the distal tip micropulser to the tissue target means that the pulse can be generated with significantly less power and without additional equipment. Lower power consumption means that the PIM can be sufficiently powered by a battery to generate the pulse, thus eliminating the need to be physically wired to the IVUS processing unit. The distal tip micropulser thus allows the disclosed wireless systems to consume orders of magnitude lower power than conventional systems. For example, the conventional, wired Philips Core Integrated IVUS system requires about 1 kW or 1000VA, whereas, embodiments configured for wireless operation in accordance with the present disclosure may require not more than about 5 uW or .000005 VA, and in some embodiments only about luW or .000001 VA. Conventional IVUS systems cannot be done wirelessly because without the disclosed distal tip micropulser such systems would draw too much power.

[0023] The microcontroller intelligence configured within the PIM enables the system to compress the raw data received from the distal tip micropulser, which can be on the order of 2 GB / s, such that it is then possible to transmit over a wireless connection. Unlike conventional systems, which9 Attorney Docket No. 19275-005WOU1would require a wired connection to achieve this level of data rate, a PIM configured according to the present disclosure wirelessly transmits the compressed data to the processing station, for example, a standalone IVUS console or an integrated angiography suite processing system.

[0024] In some embodiments, the PIM includes hardware specifically designed for lossless compression in order to pre-process the image data before wireless transmission. Such hardware may comprise a field programmable gate array (FPGA) configured to enable application of wavelet analysis, for example using harmonic wavelet transforms, in the PIM itself. Applying wavelet analysis to preprocess the data at the PIM ultimately allows for higher signal-to-noise ratio (SNR) and sharpness and is novel for IVUS data application. In other embodiments, the PIM includes a user interface for wireless control (e.g., LCD screen, blinking lights, etc.) to communicate to the user the connection of the wireless system to the IVUS processing and display console, so that the user can ensure functional wireless connection.

[0025] In a further embodiment, as illustrated in FIG. 4, in an IVUS system according to the present disclosure PIM 42 may employ rotating electronics assembly 44 connected to a rotating core 46 of IVUS catheter 12. Power is supplied to electronics assembly 44 from battery 16 by wireless inductive power coupling 48 within the PIM between battery 16 and electronics assembly 44 including microcontroller 45. PIM 42 also includes wireless transceiver 18 for data communication. With inductive power and data transmitted wirelessly, a need for complex mechanical components to transmit data power between relatively rotating components, such as an electrical slip-ring, is eliminated. In one alternative, all the catheter electronic stages including A / D front-end, digitizers, data processing, and wireless transmission unit reside on the rotating electronic assembly. The wireless transmitter on the rotating electronic assembly sends the data directly to the cart-based console or control room workstation. In a further variation, the rotating electronics assembly is in communication with a stationary electronic assembly within the PIM in order to reduce the mass of rotating components. Persons of ordinary skill may devise other alternative configurations based on the teachings contained herein. In one further example, the electronic assembly, whether fully rotating or partially rotating and partially stationary has a wireless charging interface that provides the power to the rotating electronic assembly through an inductive power coupling with an outside power source.

[0026] In further alternative embodiments, as illustrated in FIGS. 5 and 6, PIM 50 includes rails 52 (internal or external - external shown) to allow motorized longitudinal movement of the catheter core relative to the sheath (not shown) when the catheter is connected. The motor drive carriage is10 Atorney Docket No. 19275-005WOU1mechanically fixed to the catheter core and moves along the rails. In the illustrated example, rails 52 employ yoke 54 that affixes to the catheter stationary hub. As shown in FIG. 6, yoke 54 may include positional sensors 56 for detection and quantification of rotation and / or longitudinal movement, and the information produced by positional sensors 56 would be part of the data stream transmitted by wireless transceiver 18. In a further alternative, PIMs disclosed herein, such as PIM 50, may include a pullback control pad 58, for example with start / stop buttons and a display, in communication with internal processor 60 to allow the operator to initiate imaging or pullback without needing to interact with a console or image display unit outside of the sterile field. PIMs as disclosed herein may also include indicator displays (e.g., LED or LCD) 60 to give an operator operational information such as power on, battery life, rotation in progress, or pullback distance without needing to interact with a console or image display unit outside of the sterile field.

[0027] As shown in FIG. 7A, IVUS catheter 12, connected with a patient interface module, such as any of PIM 14, 42, 50 disclosed herein, extends through sterile drape 66 to the patient. Sterile drape 66 defines the sterile field above the patient. Because the PIM has no wires extending beyond the defined sterile field, it does not need to be bagged to maintain the sterile field as with conventional wired IVUS systems. Charging of the PIM is provided via inductive power coupling with inductive pad 68, located outside of the sterile field and delivering power wirelessly through sterile drape 66 by inductive coupling with an inductive power coil (not shown) disposed within the PIM. Power supply 70 provides the power source for inductive power coupling pad 68. Power supply 70 may be a wired power supply or a larger size battery-based power supply because it resides permanently outside the sterile field.

[0028] FIG. 7B shows further details of a wireless IVUS system employing any of PIM 14, 42, 50 as elsewhere described herein. In this embodiment, an inductive power coupling is provided by inductor coil 74, which is controlled by a server controller including CPU 76 and FPGA 78. This processing capacity can be used to control the inductive power coupling and power supply as well as to augment the microcontroller intelligence of processing module 26 within PIM embodiments 14, 42, 50, for example by providing image post-processing enhancements as described herein. Server 72 also includes a wireless transceiver (not shown) to provide wireless communication with the PIM as previously described. Inductive power coupling pad 68 or server 72 may reside on or be integrated into angiography table 36. As will be appreciated by persons of ordinary skill, embodiments such as exemplified by FIGS. 7A and 7B eliminate the need for a cable and sleeve that protects the cable. The catheter and drive mechanism are charged through the inductance coil and the handheld system is11 Attorney Docket No. 19275-005WOU1independent and does not need any cables to connect to a console. Many challenges and complications associated with maintaining the sterile field with conventional wired systems are thus eliminated.

[0029] Further details of alternative PIM embodiments, such as but not limited to PIM 14, 42 and 50, are described in connection with FIG. 8, which depicts an example of a control architecture for PIM embodiments disclosed herein. Battery 16 is a rechargeable battery, maintained through inductive charging (described further below) to ensure continuous readiness. The capacity of rechargeable battery 16 is selected to be sufficient to support full operation throughout the intended use period. In one example, battery 16 provides 25.9 Wh of capacity, which enables the PIM to operate reliably for at least two hours without interruption. All handheld system power rails include independent power supplies, such as control power supply 84 for microcontroller 60, wireless transceiver 18 and user interface 58, pulser power supply 86 for distal tip micropulser 13 which is integrated within the catheter tip electronics as further described below, rotational drive power supply 88 for rotational drive motor 90 and translational drive power supply 92 for translational drive motor 94. Preferably, the catheter includes plural power rails supplying the distal tip electronics and delivering impulse power for transducer 116 (see FIG. 9). In one embodiment, a catheter supply rail powers the distal tip electronics and only draws a few milliamperes at a low voltage of about 2 VDC to 5 VDC and in some embodiments only about 2.45V to 3.0V. An impulse generator supply rail is a separate rail that powers the impulse generation section and determines the impulse power. The impulse generator supply rail operates at higher current levels, up to about 450 mA in some embodiments, or more preferably not more than about 330 mA.

[0030] All power rails for the handheld system (catheter 12 + PIM) are managed through three independent control layers established by microcontroller 60, supervisory hardware section 80 and abort logic 96. Microcontroller control via microcontroller 60 selectively switches handheld system power rails ON or OFF during normal operation, communicating with system components via power and data lines 79. Supervisory section control via hardware supervisory section 80 continuously monitors power consumption across all handheld system power rails via data / control lines 82 and provides a primary safety control by enforcing power limits and preventing excessive energy delivery to handheld system components including the catheter tip electronics in case of abnormal conditions. Abort logic 96 provides an emergency abort function in response to user-accessible emergency abort button 83 by terminating power delivery through power lines 98. Abort logic 96 has the highest system priority and directly overrides both the microcontroller and software logic through the hardware supervisory section. When abort logic 96 is activated via button 83, it immediately disables all12 Attorney Docket No. 19275-005WOU1handheld system power rails and halts the motors. Power rails remain latched in the OFF state until the user manually clears the abort condition, which may be via user interface 58 or a reset button (not shown) directly acting on abort logic 96. This multi-layered approach to power control ensures robust operational control while providing redundant safety protections against unintended power delivery.

[0031] The catheter supply rail is typically always active when the catheter is in use. However, it may be preferred to manage current more discretely in the impulse generator supply rail for thermal management reasons and thus it may not be continuously active when the catheter is in use. For example, microcontroller 60 may control current in the impulse generator supply rail to ramp up gradually about a microsecond before impulse generation, then decay slowly after the impulse, and is maintained at a very low level until the next impulse. This approach may minimize average heat dissipation while still providing the required impulse energy. The peak current on this rail determines the impulse power.

[0032] In one example embodiment, hardware supervisory section 80 includes voltage monitoring relays to monitor the catheter supply power rail and trigger an emergency abort when excessive voltage or current draw is detected. In examples described herein, voltage supply out of range may be set as detected voltage greater than about 5.0 VDC, or more preferably, about 3.0 VDC and current supply out of range may be set as detected current greater than about 20 mA, or more preferably about 15 mA. Hardware supervisory section 80 also may include Hall effect sensors, current shunt resistors or overcurrent protection (OCP) circuits to monitor the impulse-generator supply rail (peak and DC average currents) and triggers an emergency abort when excessive peak or average current is detected. In examples described herein peak DC supply-rail current abort may be triggered when current exceeds about 330 mA and average DC supply rail current exceeds about 50 mA. Hardware supervisory section 80 also may use current sensors such as shunt resistors or Hall effect sensors in combination with a microcontroller to monitor rotational drive motor 90 (and translational drive motor 94 where applicable) and trigger an emergency abort when overspeed or excessive power draw is detected. In examples described herein, rotational drive motor overspeed may be set at 1,900 RPM or higher and excessive rotational drive motor power draw may be set as exceeding about 10 W.

[0033] In a preferred embodiment, hardware supervisory section 80 is comprised of discrete analog and digital electronic circuits so its functions would not be prone to errors or glitches. In such13 Attorney Docket No. 19275-005WOU1an embodiment, the supervisory circuits operate deterministically within their design limits and do not require calibration, firmware, or external intervention.

[0034] With the micropulser 13 integrated within the catheter tip electronics at the distal end of catheter 12, impulse power is supplied to the tip electronics from the PIM via a dedicated DC rail through catheter 12. At the tip, micropulser 13 converts this DC rail power into the short, high- intensity electrical impulses required to trigger the ultrasonic transducer 116 (see FIG. 9). The use of the distal tip micropulser 13, as described in more detail below, permits the PIM to supply only a low- voltage, low-power DC rail to the catheter tip electronics. In one example embodiment, average DC power required for impulse generation is typically not more than about 35-40 mW and in some embodiments only about 29 mW, notwithstanding the fact that momentary impulse power at the distal tip may reach 18 W or higher.

[0035] In embodiments of the present disclosure, although the instantaneous impulse power can be high, the low duty cycle ensures that the average power requirement remains very low. In one illustrative example, the DC catheter impulse rail operates over a voltage range of about 0.9 V to about 3.6 V, with the average current strictly limited to 50 mA by the hardware supervisory control. This translates to a maximum deliverable power of 180 mW (3.6 Vx50 mA) — a value intentionally set as a safety limit. Continuing with this example embodiment as an illustration, typical operation may require only about 29 mW of average impulse power, well below the supervisory control limit. Moreover, for specialized imaging scenarios such as stent visualization — where the target has a high ultrasonic reflection index — the handheld system reduces the impulse power to as little as 1% of the maximum setting, bringing average power down into the microwatt range while still achieving reliable transducer excitation.

[0036] While the momentary impulse power reaches 18.6 W, each pulse has an extremely short duration of only 25 nanoseconds. When the pulse duty cycle is taken into account, the average impulse power during typical operation is only about 29 mW as mentioned above. For safety, the hardware supervisory control 80 enforces an upper limit on average impulse power of 180 mW, which is approximately 1% of the instantaneous peak power. This ensures that even under abnormal conditions, total delivered energy remains well below potentially hazardous levels. The impulse generation circuit itself is powered via a DC supply rail delivered to the catheter tip electronics, providing stable and controlled energy for pulse formation.14 Attorney Docket No. 19275-005WOU1

[0037] In addition to the impulse rail, the catheter incorporates a low-voltage supply rail dedicated to powering the tip electronics. In some embodiments, this rail may operate at between about 2.45 V and about 3.0 V, with a nominal current draw of only about 8 mA. At the nominal operating point of 2.75 V, this corresponds to approximately 22 mW of supply power (2.75 V x 8 mA). For safety, the hardware supervisory section 80 enforces a current limit of 15 mA maximum. At the highest rail voltage of 3.0 V in this embodiment, this equates to a maximum deliverable power of about 45 mW (3.0 V x 15 mA). This current limiting ensures that even in fault conditions, total supply power remains within a tightly controlled and safe envelope.

[0038] In contrast to embodiments disclosed herein, the current state of the art conventional IVUS systems generate the impulses in the proximal handheld unit (e.g. PIM), forcing all of the instantaneous energy for pulse generation to travel the entire catheter length through cables within the catheter body. As a result, conventional IVUS systems must overcome a number of significant challenges, including electrical loss along the wiring, electromagnetic emissions due to high peak currents, and increased complexity and cost in catheter manufacturing. In such conventional systems, impulses generated proximally must travel through -130 cm (- 1300 mm) of catheter wiring, which also increases susceptibility to distortions due to coupled noise, reflections and ringing artifacts.

[0039] Embodiments disclosed herein avoid these challenges and signal distortions because they transmit only low-voltage DC power along the catheter power rails to the distal tip micropulser, eliminating issues arising from long-wire impulse transmission losses and minimizing EMI. Another benefit of distal impulse generation as taught herein is the cleanliness of the electrical pulse produced. In disclosed embodiments, the impulse is generated in close proximation to the transducer, meaning the electrical waveform reaches the transducer essentially untouched. The transducer receives a pure sinusoidal pulse, free of reflections, ringing, or noise coupling. “Close proximity” in this context means not more than about 5 mm distant and, more preferably, a distance of 1 mm or less. In some embodiments, the pulse generation circuitry is less than 0.5 mm behind the transducer.

[0040] The same issues also apply to return signals from the transducer back to the PIM. In conventional IVUS systems, the tiny charges generated by ultrasonic reflections must travel the full catheter length (-1300 mm) before reaching the first amplifier, accumulating noise and distortion. In embodiments of the distal pulser disclosed herein, the architecture instead places a first amplification and impedance-matching stage in close proximity to the transducer (as defined above), so the signal is stabilized and amplified before traveling down the catheter. This preserves waveform fidelity and15 Atorney Docket No. 19275-005WOU1prevents reflections or ringing in transmission, which greatly facilitates further processing in the handheld system and wireless transmission as explained below.Examples of Wireless Modes

[0041] In one example embodiment, sampling of the pre-amplified IVUS transducer signal is performed at a sampling rate in the range of about 500MSPS to about 2 GSPS. In other embodiments the sampling range is narrower, from about 500MSPS to about 1 GSPS. Wavelet transform and Hilbert-envelope detection is executed in microcontroller 60, which may include an FPGA dedicated to these functions. The wavelet and Hilbert processing provides a beneficial side effect of reducing signal size / sampling rate by 5-10 times. The signal with this initial reduction requires less compression for wireless transmission. Lossless compression using standard compression algorithms is then applied to the processed and reduced signal in order to transmit the signal over a wireless 802.1 1 link. Examples of suitable lossless compression algorithms for this purpose include Huffman Coding, which assigns shorter bit codes to more frequent symbols and longer codes to less frequent ones, Arithmetic Coding, which represents the entire message as a single number between 0 and 1, achieving higher efficiency than Huffman in some cases, and Adaptive Huffman / Arithmetic, which adjusts symbol probabilities dynamically while reading input.

[0042] The compressed imaging signal is then transmitted from PIM wireless transceiver 18 to the server wireless transceiver 22 using an 802.11 wireless protocol. Depending on initial sampling rate, because of the initial signal reduction through the wavelet and Hibert processing, the imaging signal as compressed by one of the above techniques typically may be transmitted via the prior generation 802.1 lax (WiFi 6) protocol or in some cases an earlier 802.11 protocol. Once received at server 20, additional post processing image enhancements like image contrast, brightness, gamma correction, and other visual improvements may be applied before transmitting the processed signal to external display 24 for presentation on the screen.

[0043] In other alternative embodiments, one or more elements of post-processing enhancements also may be performed in PIM microcontroller 60 and thus further reduce the size of the signal prior to compression. For example, improvements such as noise reduction and logarithmic conversion could be applied in microcontroller 60 to improve compression efficiency and further reduce data size.

[0044] In a further alternative example embodiment, with sampling of the pre-amplified IVUS transducer signal in the range of about 500MSPS to about 1 GSPS, the “raw” signal potentially may be compressed with standard compression algorithms as described above. However, due to the size16 Attorney Docket No. 19275-005WOU1of the “raw” signal even after compression, wireless transmission would likely require the most recent 802.11be protocol or a later, as yet unreleased protocol, for effective wireless transmission. In this example, server 20 will run the Wavelet transform and Hilbert-envelope detection as well as apply appropriate post processing image enhancements like image contrast, brightness, gamma correction, and other visual improvements before display on external display 24.

[0045] In another electronics configuration, a magnetically coupled interface between the rotating electronic and the stationary section is a dual function interface. It provides inductive power to the rotating electronic assembly, and acts as a high-speed digital data exchange interface between the two modules. Two coils are used for power induction, and two antennas, one on each side, are used for data exchange. The A / D front-end and digitizers reside on the rotating electronic assembly, and the digitized data is transmitted to the other side by a standard RF modulation scheme. This can be a high data rate ultra- wideband modulation (UWB), or a WiFi, or other protocols. For example, the protocol for this few millimeters distance data change can use a 5G communication protocol. As the transmitter and receiver antennas are in proximity of each other, the link can maintain the nominal 20 Gbps maximum data rate of a 5G network continuously. In this configuration, the systems data processing unit and the main wireless transmitter both stay on the stationary electronic assembly. This makes the rotating electronic PCB size smaller than the first configuration.

[0046] In a further electronics configuration, a contactless rotating interface is a pure analog stage. One or more fixed magnets and a coil are placed on the stationary side of the interface. A second coil on the rotating side is moving continuously across the magnetic field and generates alternating current in the rotating coil. This current is rectified, converted to a DC voltage and is used to power the rotating analog circuit. The rotating analog circuit has a built-in transducer that amplifies and a simple PWM or PDM modulator. The output of the modulator is connected to the rotating coil. The primary and secondary coils act as a transformer and the amplified transducer signal is transferred to the stationary electronic assembly through the coils. All the A / D front-end, digitizers, processing, and wireless transmission happen on the stationary electronic assembly. The PWM or PDM modulation eliminates the impact of the signal fluctuations. The AC current produced in the rotating coil is significantly lower in frequency than the data rate, and can be easily separated. For example, in a system with 30 Hz display refresh rate and a single magnet, the AC current produced is 30 Hz while the PWM or PDM data rates are several megahertz. This configuration has the smallest rotating electronic assembly footprint size.17 Attorney Docket No. 19275-005WOU1Examples of Distal Tip Micropulser

[0047] As explained above, a near-perfect signal preservation is critical for enabling advanced processing such as the wavelet transform and Hilbert envelope detection. For example, a wavelet transform requires comparison against a known “expected” waveform. If the received signal is corrupted by noise, ringing, or reflections — as happens in conventional designs — accurate comparison becomes impossible. By maintaining signal purity from transducer to amplifier, disclosed systems achieve practical implementation of wavelet transforms in IVUS, which is an important improvement over conventional systems. Embodiments of distal micropulsers which allow these improvements will now be described.

[0048] As shown in FIG. 9, one embodiment of distal tip micropulser 13 includes imaging core 110, which may be configured as a rotatable guidewire-type structure, having a housing 112, terminating in distal end 113. Positioned adjacent distal end 113 is distal control module 114 and ultrasound transducer 116, which are joined by current-conducting connectors 118 in the illustrated embodiment. Ultrasound transducer 116 may comprise a PMUT. Alternatively, as further discussed below, distal control module 114 and transducer 116 may be integrated together in a single electronics package, and other transducer types may be employed as alternatives to the PMUT shown in FIG. 9. Power rails to the distal micropulser are provided by electrical cable 120, which extends from the proximal circuit (not shown) to the distal control module 114, provides at least two conductors 120A, 120B (FIG. 11). Transducer 116, when configured as aPMUT, includes transducer portion 122, which is positioned in an open window provided in epoxy 124 (or similar filler / fixing material) within the distal end of housing 112 surrounding at least distal control module 114 and transducer 116. During use, imaging core 110 is deployed within catheter sheath 126 as is known in the art. Further aspects of imaging core 110 not otherwise described below may be adapted by persons of ordinary skill in the art based on conventional imaging systems, such as disclosed in U.S. Patent No. 6,450,964, which is incorporated herein by reference in its entirety.

[0049] Systems and circuits disclosed herein are configured in certain embodiments to generate clean and discrete sinusoidal pulses, which may be single pulses, double pulses, or “n” number of pulses. A clean sinusoidal pulse refers to one or more discrete sinusoidal pulses that are free of or at least substantially free of or eliminate ringing or continuous oscillations beyond a zero-crossing point at an end of the specified n-number sinusoidal pulse. For example, a series of clean single (n=l) sinusoidal pulses are illustrated in FIG. 13. In another example, a series of clean double cycle (n=2) sinusoidal impulses are illustrated in FIG. 14. In a further alternative, the n value may be changed18 Attorney Docket No. 19275-005WOU1between pulse cycles to produce a series of different number pulse cycles, for example, by alternatingly switching between n=l and n=2, a series of alternating clean single and double cycles may be produced.

[0050] FIG. 10 illustrates a pure pulse system according to the present disclosure in which control logic circuit 136 drives switch circuit 132 off and on for transducer tank circuit 130, which drives an optional current sense circuit 134. As further described below, transducer tank circuit 130 may comprise an ultrasonic transducer, such as a PMUT, providing capacitance (C) in series with an inductor (L). Control logic circuit 136 and current sense circuit 134 also may be optionally provided in a single ASIC configuration. With such an arrangement, switch circuit 132 has the ability to remove energy from transducer tank circuit 130 to prevent resonant oscillations from being produced by the transducer. Stored energy is instead shunted to the current return when the switch circuit is turned back on during a negative part of the generated signal pulse to prevent ringing of the signals as further described below.

[0051] In operation, during an initial sinusoidal positive pulse, switch circuit 132 turns off to redirect current flow from the switch circuit to the transducer tank circuit 130. During the negative portion of the pulse, current is prevented from going “back” through the switch circuit. Switch circuit 132 can be turned on by control logic circuit 136 at any time during the negative part of the pulse. This is an advantage since the timing does not need to be precise. Switch circuit 132 timing is illustrated in the detail view in FIG. 13, wherein time reference A indicates the “turn off’ time for the switch circuit to generate the pulse with transducer tank circuit 130. Time reference B indicates the time interval during which the switch circuit 132 can be set to “on” in order to suppress ring down and generate a clean, single pulse signal. Switch circuit 132 is thereafter maintained as “on” until the next pulse is desired at time reference A. Switch circuit 132 thus has more time to turn on during time interval B of the sinusoidal signal, which is advantageous, especially at high frequencies.

[0052] In some embodiments, current sense circuit 134 is configured to verify that a pulse is being generated and provide feedback to the system. For example, sense circuit 134 (or 162 below) could be used to determine if transducer 116 is in the right range and that the transducer is not over driven by the distal tip micropulser circuit. The functional verification can be controlled with an ASIC incorporating the current sense circuit.

[0053] FIG. 11 illustrates an example implementation of distal tip micropulser circuit 140 according to the present disclosure. Distal tip micropulser circuit 140 may be distributed across19 Attorney Docket No. 19275-005WOU1multiple physical electronics components or integrated into a single electronics package. In the example of FIG. 11, distal tip micropulser circuit 140 includes inductor 142 to store energy, and two switches: a controllable switch 146, in one example a MOSFET including a parasitic diode; and a oneway switch 144, for example a diode. Control logic 150 drives controllable switch 146. Inductor 142, diode 144, and controllable switch 146 are configured in a serial manner. Transducer 116, which may be aPMUT in some embodiments, is connected to junction 148 of inductor 142 and diode 144. In this example, transducer 116 and inductor 142 comprise transducer tank circuit 130; controllable switch 146 and diode 144 comprise switch circuit 132; and control logic 150 comprises logic circuit 136.

[0054] When controllable switch 146 is ON, one-way (diode) switch 144 is configured in a conduction mode. This will keep inductor 142 and transducer junction 148 in near-zero voltage. When a pulse is desired, controllable switch 146 will be turned off. This will direct stored energy from inductor 142 to transducer 116, which has a known capacitance.

[0055] In operation, for a first pulse half-cycle, controllable switch 146 will be off, and only inductor 142 and transducer 116 capacitance is in series. The inductor’s stored energy will generate a variable current and voltage at junction 148 in accordance with the following equation:where: “i” is current, “t” is the time, “L” is the inductor’s inductance, “C” is transducer capacitance, and “Vo” is the initial voltage, which is close to zero, and the “co ” is the resonance frequency of the sine wave. When the voltage again reaches zero, it will continue in the negative direction. In this area, controllable switch 146 becomes conductive, but the external series one-way (diode) switch 144 will be biased backward and keeps inductor 142 and transducer 116 capacitance isolated. As long as no external force (a current load from adjacent circuits) is applied to the L / C sub-circuit formed by inductor 142 and transducer 116, they will continue according to the above equation in the negative territory and the waveform will remain a complete sinusoidal wavelet. In other words, diode 144 acts as a blocking diode to prevent current from going back through the transistor switch when the transistor is turned off.

[0056] A sinusoidal current in inductor 142, while it is only in series with transducer 116 capacitance, generates a sinusoidal voltage across transducer 116. Stored energy in a capacitor is according to the formula 0.5*VA2*C, where “C” is the capacitance and “V” is the voltage across the20 Atorney Docket No. 19275-005WOU1capacitor. In the absence of any parallel accessory circuit, the entire energy from inductor 142 will be transferred to the transducer 116 capacitance and this will convert the stored energy inside inductor 142 to a voltage across transducer 116. A fixed current “I” is set through conductor 120A of cable 120 inside the device. This is used to set the impulse power. At the distal end 113 of the device, this current is passed through inductor 142. The inductor will store energy equivalent to 0.5*IA2*L, where I is the set current, and L is the inductance. Current sense circuit 162 optionally can be used to determine current to transducer 116.

[0057] In one example, with controllable switch 146 configured as MOSFET, the inductor current is periodically interrupted. MOSFET can be silicon-based or GaN MOSFET with a control logic circuit 150 as shown in FIG. 11. In this example, a second switch is a high voltage diode acting as one-way switch 144. These two switches are in serial with inductor 142. The diode polarity is set so it is typically in the conduction mode. Junction 148 between inductor 142 and the diode 144 is connected to transducer 116. Transducer capacitance and this inductor form a resonance (tank circuit) at the desired ultrasonic frequency.

[0058] In a further illustration of this example, an ASIC may be configured as MOSFET control logic circuit 150. In such an embodiment, main ASIC power supply rail 158 drives the MOSFET logic circuit 150 and supplies power thereto. Ground pathway 156 is the ground for the control logic.

[0059] Control gate output 160 is used to drive the MOSFET logic circuit. When this is low, the MOSFET is not conducting and when it is high, the MOSFET is conducting. Gate control 1 (152) is used for output protection purposes. Gate control 1 (152) is typically pulled low, however, if current sense circuit 162 senses an overcurrent in the transducer, this pin is pulled high. This will keep the control gate output 160 permanently at a high state and would prevent the MOSFET from turning off. This prevents the initiation of a new pulse generation until the overcurrent state is cleared. Gate Control 2 (154) is the main MOSFET gate control. When gate control 2 (154) is pulled low and no over-current is sensed, output 160 will follow and this pulls output 160 low. This initiates impulse generation by turning off the MOSFET 146.

[0060] Control logic circuit 150 typically keeps the MOSFET ON. In this configuration, the current “I” will pass through the inductor 142, diode 144, and MOSFET 146, and transducer 116, with voltage kept near zero. Transducer 116 capacitance and inductor 142 form a tank circuit. When an impulse is desired, the ASIC turns off MOSFET 146. Interruption of the MOSFET conductivity directs the current “I” to the transducer 116 capacitance, which would be the only option when21 Attorney Docket No. 19275-005WOU1MOSFET turns off, and sinusoidal wavelet formation begins. After half a cycle and when the voltage turns negative, MOSFET 146 turns ON. As diode 144 will be biased backward, it will keep the L / C isolated from the MOSFET parasitic diode and the sinusoidal wave continues in the opposite direction with disregard to the MOSFET status.

[0061] FIG. 11 A illustrates alternative distal tip micropulser circuit 140A in which inductor 142 and transducer 116 are arranged in parallel rather than in series as in the embodiment shown in FIG. 11. In alternative distal tip micropulser circuit 140A, conductor 120A provides current to the parallel sub-circuit comprising inductor 142 and transducer 116, which provides the capacitance (C). Optional current sensor 162 can be provided in the transducer branch of the parallel sub-circuit, which connects to the switch circuit comprised of one-way (diode) switch 144 and controllable on / off switch 146 at junction 148. Controllable switch 146 may be configured as described herein and may connect to a control logic circuit via control gate output 160 as described above.

[0062] As will be appreciated by persons of ordinary skill based on the teachings described herein, an advantage of the described circuits arises from the ability of the transistor and the diode to remove energy from the LC resonant pair wherein the capacitance (C) is provided by the transducer element. The ability to prevent the LC resonant oscillations from happening is accomplished by preventing current from going back into the inductor. The stored energy is shunted to ground when the transistor is turned back on during the negative part of the signal. This prevents ringing of the signal. Finally, as the signal returns to positive, the diode clamps the voltage at the end of the sinusoidal pulse. This results in a single wave form being produced.

[0063] A control ASIC configured as mentioned above can turn on during this second portion of the wavelet without affecting the wavelet shape. Diode 144 is in reverse polarity at this time and will keep the transducer / inductor separated from the MOSFET 146. In one illustrative example, for a 50 MHz wave, the second portion of the wavelet is 10 nS. Control logic circuit 150 can close MOSFET 146 at any time during the second portion of the wavelet. For the given example, the MOSFET can be turned on at 15 nS + / - 5 nS after the initial MOSFET off state, without impacting the wavelet shape. In other words, the timing circuit can close the switch at any time during the second portion of the wavelet. This arrangement gives flexibility to the timing logic and eliminates the tight timing requirements.

[0064] As soon as transducer 116 voltage crosses zero, MOSFET 146 is already ON and diode144 starts conducting. Inductor 142, MOSFET 146, and diode 144 again are in a conduction scenario,22 Attorney Docket No. 19275-005WOU1and the set current “I” passes through this pathway. Current “I” starts charging inductor 142 with energy for the next impulse request. See FIG. 13 for a single-cycle sinusoidal impulse generated by the described example distal tip micropulser circuit of FIG. 11.

[0065] An advantage of disclosed embodiments is the “stacked” voltage tolerance of switches 144, 146. For the circuit embodiment shown in FIG. 11 where an N-channel MOSFET is used, the MOSFET only sees the positive transducer voltages and the diode only sees the negative transducer voltages. The total maximum peak-to-peak voltage applied to the transducer can be as high as the combined maximum voltage tolerances of the MOSFET and diode. For example, if the maximum permissible voltage to the MOSFET drain-source is 100 volts, and the maximum allowed reverse voltage on the diode is 100 volts, then the maximum peak-to-peak voltage on the transducer can be as high as 200 volts.

[0066] In one example, using a PMUT, transducer voltage can be as high as 200 volts. As described before, an increase in the voltage applied to the PMUT exponentially increases the output power. MOSFETs with the desired parameters and several hundred volts drain-source tolerance are available in sub-millimeter dimensions. The same is the case for diodes. As a further example, 200 volts stacked MOSFET and diode voltage will result in a 12 dB improvement over a 50 volts peak-to- peak drive. This directly translates into 12 dB improvements in the processed image signal-to-noise ratio.

[0067] As mentioned before, a simple circuit at the proximal side of the system can adjust the inductor current. This eliminates any impact the transmission line 120 loss would have on the pulse wavelet shape. The internal lumen of an IVUS catheter is very small and wires or microcoaxes used to transfer the electrical power can exhibit noticeable resistance and loss. Described embodiments lessen or eliminate the impact of transmission fosses on the impulse energy and wavelet shape. Regardless of the line resistance, the inductor energy is only dependent on its set current with the equation 0.5*IA2*L. Both current “I” and the inductance L, are independent of the transmission line losses.

[0068] In a typical IVUS catheter the wires have to pass through a rotary junction. This will introduce additional signal loss and noise sources. Once again, the described approach of adjusting the line current will eliminate the impact of a rotary joint on the wavelet shape as well. Variations in joint impedance will be compensated by the set current control circuitry. The wavelet power and23 Atorney Docket No. 19275-005WOU1shape will remain independent of the rotary joint impact and the image quality will not be adversely affected by the joint motions.

[0069] If more than one cycle of a wavelet is desired to produce a chirp, the control circuitry or ASIC can initiate a cycle with the same approach, turning off controllable switch 146 (e.g. MOSFET). The turn ON will happen at any time during the negative portion of the ending cycle. For example, if two cycles of a 50MHz wavelet is desired, the controllable switch 146 can be turned back on at 35 nS + / - 5 nS. For three sinusoidal cycles, the turn-on will be at 55 nS + / - 5 nS, and so on. See FIG. 14 for a two-cycle impulse generated by the described example circuit of FIG. 11.

[0070] Alternatively, as controllable switch 146, a MOSFET can be replaced by a bipolar junction transistor. In such an alternative configuration, instead of a gate control voltage for the MOSFET, a small current is applied to the base-emitter of a bipolar junction transistor to keep it on. Reducing this current to zero will turn off the transistor and will have a similar effect as turning off the MOSFET.

[0071] In a typical IVUS catheter, the pulses are synchronized with the motor driving the torquecable. The torque cable running through the length of the catheter and at the distal end (transducer side) may not be fully synchronized with the motor. This can generate image artifacts. As a further feature of embodiments disclosed herein, as the pulses are generated at the distal side and accessible to the control distal control module or ASIC there, interruptions of the current to generate an impulse can be synchronized with a mechanical feature on the distal portion of the catheter (transducer side). For example, as illustrated in FIG. 15, in one embodiment, a small magnet 170 attached to catheter sheath 126 can be sensed as the starting zero angle using a Hall effect sensor 172 disposed on control module 114 or a portion of transducer 116 at distal end 113 of imaging core 110. Alternatively, as shown on FIG. 16, marking 174 on catheter sheath 126 can be sensed by an optocoupler or microswitch 176, also disposed alternatively on control module 114 or a portion of transducer 116 at distal end 113 of imaging core 110. In this manner, pulses can synchronize the image with the catheter sheath and eliminate image disturbances and artifacts due to torque-cable wiggling.

[0072] FIG. 12 illustrates one configuration of a circuit board / block diagram for implantation of distal control module 114 according to the present disclosure. In this example, transducer 116, configured as a PMUT, is connected to distal control module 114 via castellated conductors 118. In addition to components discussed above in connection with FIG. 11, control module 114 as shown in FIG. 12 includes conductive pads 164 for connection of conductors 120A, 120B of cable 120. In this case, current sense circuit 162 is realized using two clipping diodes (D2, D3). In further alternative24 Attorney Docket No. 19275-005WOU1embodiments, distal control module 114 may also include one or more of pressure, flow and temperature sensors. Distal control module 114 also includes ultrasound signal amplification circuitry as appropriate to the transducer type and power levels. Such amplification circuitry can be incorporated into an ASIC with other control functions as described above.Microcontroller Architecture

[0073] In embodiments disclosed herein, controllers such as internal controller 17, server 20, the server of integrated console 34, microcontroller 45 and microcontroller 60 among others, may be executed as one or more controllers 1700 configured as a computing device as illustrated in FIG. 17. Thus, the term “controller” as used herein describes a structure that includes at least a processor configured to execute stored instructions and may additionally include other structural components described herein as may be devised by persons of ordinary skill in the art based on the teachings of the present disclosure including incorporated by reference disclosures. In this example, controller 1700 includes one or more processors 1702, memory 1704, storage device 1706, high-speed interface 1708 connecting to memory 1704 and high-speed expansion ports 1710, and a low-speed interface 1712 connecting to low-speed buss 1714 and storage device 1706. Each of the components 1702, 1704, 1706, 1708, 1710, and 1712, are interconnected using various busses or other suitable connections as indicated in FIG. 17 by arrows connecting components. Processor 1702 can process instructions for execution within the controller 1700, including instructions stored in the memory 1704 or on the storage device 1706 to display graphical information via GUI 1718 with display 1720, or on an external user interface device, coupled to high-speed interface 1708. In other implementations, multiple processors and / or multiple busses may be used, as appropriate, along with multiple memories and types of memory. Also, multiple controllers 1700 may be connected, with each device providing portions of the necessary operations (e g., as a server bank, a group of blade servers, or a multiprocessor system).

[0074] Memory 1704 stores information within the controller 1700. In one implementation, the memory 1704 is a computer-readable medium. In one implementation, the memory 1704 is a volatile memory unit or units. In another implementation, the memory 1704 is a non-volatile memory unit or units.

[0075] Storage device 1706 is capable of providing mass storage for the controller 1700, and may contain information such as the database of tile display information described hereinabove. In one implementation, storage device 1706 is a computer-readable medium. In various different25 Atorney Docket No. 19275-005WOU1implementations, storage device 1706 may be a floppy disk device, a hard disk device, an optical disk device, or a tape device, a flash memory or other similar solid state memory device, or an array of devices, including devices in a storage area network or other configurations. In one implementation, a computer program product is tangibly embodied in an information carrier. The computer program product contains instructions that, when executed, perform one or more methods, such as those described above. The information carrier is a computer- or machine-readable medium, such as the memory 1704, the storage device 1706, or memory on processor 1702.

[0076] High speed interface 1708 manages bandwidth-intensive operations for the controller 1700, while low speed interface 1712 manages lower bandwidth-intensive operations. Such allocation of duties is exemplary only. In one implementation, high-speed interface 1708 is coupled to memory 1704, display 1720 (e.g., through a graphics processor or accelerator), and to high-speed expansion ports 1710, which may accept various expansion cards (not shown). In the implementation, low-speed interface 1712 is coupled to storage device 1706 and low-speed buss (expansion port) 1714. The low- speed buss, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet) may be coupled to one or more input / output devices as part of GUI 1718 or as a further external user interface, such as a keyboard, a pointing device, a scanner, or a networking device such as a switch or router, e.g., through a network adapter.

[0077] Various implementations of the systems and techniques described here can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include implementation in one or more computer programs that are executable and / or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device.

[0078] These computer programs (also known as programs, software, software applications or code) include machine instructions for a programmable processor, and can be implemented in a high- level procedural and / or object-oriented programming language, and / or in assembly / machine language. As used herein, the terms “machine-readable medium” “computer-readable medium” refers to any computer program product, apparatus and / or device (e.g., magnetic discs, optical disks, memory, Programmable Logic Devices (PLDs)) used to provide machine instructions and / or data to a26 Atorney Docket No. 19275-005WOU1programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0079] To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having a display device (e.g., an LED, OLED or LCD display) for displaying information to the user and a keyboard and a pointing device (e.g., a mouse or a trackball) by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0080] The systems and techniques described here can be implemented in a computing system that includes a back end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of wired or wireless digital data communication (e.g., a communication network). Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), and the Internet.

[0081] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.Wavelet Analysis

[0082] As mentioned previously, using signals generated by the distal tip micropulser 13, harmonic wavelet transforms may be applied to achieve a high SNR in the reflected signal across a broad range of frequencies. Wavelet transforms maintain phase information accurately. The disclosed systems use wavelet transforms to significantly improve the SNR and purify the reflected signal, resulting in a much higher resolution in the constructed image. In some embodiments, the system uses a combination of wavelet transforms as well as a Hilbert transform. In one example embodiment, the reflected electrical signal has a 65 dB SNR, as compared to 40 dB in current state of the art systems.27 Attorney Docket No. 19275-005WOU1

[0083] FIGS. 18A-E present a series of graphs showing an example wavelet transform analysis according to an embodiment of the present disclosure. It demonstrates the principle of applying a wavelet transform to an acquired complex signal in order to filter the signal to the level of detail the user is interested in viewing for a specific image. In this example, the broadband IVUS system acquires a broadband signal 178 (FIG. 18A). A wavelet transform is applied to decompose the broadband signal 178 into Approximate Coefficients 180 (FIG. 18B) from a low pass filter, and Detail Coefficients 182, 184, 186 from a high pass filter (FIGS. 18C-E). This is repeated to a defined set of wavelet “levels”. In this example, there are three wavelet levels: Detail Coefficients 182, Detail Coefficients 184, and Detail Coefficients 186. The broadband signal 178 is matched against each of the three wavelet levels, and the frequencies matching each level pattern are extracted, as shown at 182, 184, 186. These wavelet components of the original broadband signal 178 are subsequently converted to images by applying an inverse wavelet transform.

[0084] By applying the wavelet transform, the broadband IVUS system can isolate the frequency within the broadband signal 178 that corresponds to the level of detail containing a specific physiologic feature, which is displayed in the resultant IVUS image. The wavelet components can be combined in different ways to customize the properties of the IVUS image. For example, the broadband IVUS system can use wavelet transform to isolate the frequency level corresponding to blood speckle noise and subtract it from the original broadband frequency image, so that the user views an enhanced image of the target anatomy with blood speckle removed. Blood speckle is a common artifact, but can make identifying the lumen-intima border difficult, for example. These techniques also advantageously reduce the signal size as discussed above.

[0085] Additional details on wavelet transforms and Hilbert edge detection as applied to signals generated by embodiments of distal micropulser 13 and similar devices is provided in Applicant’s concomitantly filed PCT application entitled “Systems and Methods for Detecting Broadband Frequencies in Intravascular Ultrasound” identified by Attorney DocketNo. 19275-006WOU1, which is incorporated by reference herein in its entirety. Further details and general explanatory material on wavelet transforms is available in the publication Daubechies, Ten Lectures on Wavelets, CBMS-NSF regional conference series in applied mathematics, Lectures delivered at the CBMS conference on wavelets, University of Lowell, Mass., June 1990, Philadelphia: Society for Industrial and Applied Mathematics (SIAM), 1992, which is incorporated herein by reference in its entirety.28 Attorney Docket No. 19275-005WOU1

[0086] Disclosed embodiments of ultrasound catheters have a distal tip micropulser that does not need a high frequency signal to be sent over transmission lines or cables from a console. The distal tip micropulser creates the high frequency signal and only requires a standard energy supply to control the ultrasound catheter. Since a high frequency signal is generated at the distal pulser, it makes it possible to eliminate the highly insulated cables. Advantages of disclosed embodiments include simplification of the clinical workflow without the need for sterile bags over cables. Although inductance charging has been used for charging cell phones and other devices, it is not utilized in surgical areas, especially with ultrasound catheters. This is due to the type of signal that needs to be transmitted for these ultrasound catheters. The distal pulser makes the signal that needs to be transmitted similar to that used in other standard technologies.

[0087] Embodiments of the present disclosure further comprise a small, battery-powered interface unit that provides the catheter connection, any motor drive needs, and wireless transmission of data to the image processing and display unit (e.g. console). In some embodiments the interface unit may also perform analog-to-digital conversion of the signal from the catheter. A / D circuitry and digitization may be done with an ASIC.

[0088] In other embodiments the interface unit may also contain a slip ring to provide electrical or optical connection between a rotating catheter core and stationary elements in the interface unit. In a further alternative embodiment without a slip ring, the interface unit may employ a transmitter on a rotating carrier.

[0089] In another embodiment, the interface unit may perform all A / D and computational methods necessary to form the images and transmit a ready-to-display video signal (e.g., HDMI). The interface unit may alternatively transmit image data directly to a common display for all of the catheterization lab imaging.

[0090] Power rails or rails as used herein refers to conductive pathways between source and powered functional component. “About” when used herein with reference to a value or range is used in its plain and ordinary sense as understood by persons of ordinary skill in the art as referring to standard tolerances for the referenced parameter, and when standard tolerances are not applicable, a value or range of values defined with “about” is met when a change in the range or value changes the performance characteristics of the relevant parameter or the performance characteristics of the system as a whole by not more than five percent (5%). “Logic” as used herein refers to a specific class of switching structures (e.g., a logic gate), which may be executed with analog or digital gates. Near29 Attorney Docket No. 19275-005WOU1real-time (NRT) describes data or a system that operates with a slight but acceptable delay between the event and when its data is processed and available. In the context of the present disclosure unless otherwise defined herein, a slight but acceptable delay is not more than about 800 milliseconds, except with reference to imaging using a stationary catheter a latency of up to about 2 s is an acceptable delay.

[0091] The foregoing has been a detailed description of illustrative embodiments of the disclosure. It is noted that in the present specification and claims appended hereto, conjunctive language such as is used in the phrases “at least one of X, Y and Z” and “one or more of X, Y, and Z,” unless specifically stated or indicated otherwise, shall be taken to mean that each item in the conjunctive list can be present in any number exclusive of every other item in the list or in any number in combination with any or all other item(s) in the conjunctive list, each of which may also be present in any number. Applying this general rule, the conjunctive phrases in the foregoing examples in which the conjunctive list consists of X, Y, and Z shall each encompass: one or more of X; one or more of Y ; one or more of Z; one or more of X and one or more of Y ; one or more of Y and one or more of Z; one or more of X and one or more of Z; and one or more of X, one or more of Y and one or more of Z.

[0092] Various modifications and additions can be made without departing from the spirit and scope of this disclosure. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present disclosure. Additionally, although particular methods herein may be illustrated and / or described as being performed in a specific order, the ordering is highly variable within ordinary skill to achieve aspects of the present disclosure. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this disclosure.

[0093] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the spirit and scope of the present disclosure.30 Atorney Docket No. 19275-005WOU1

Claims

What is claimed is:1 . A wireless intravascular ultrasound (TVUS) imaging system, comprising: an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; and a patient interface module (PIM) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM wireless transceiver and the distal tip micropulser, and a battery configured to power the PIM and the distal tip micropulser, wherein the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission and the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal.

2. The system of claim 1, further comprising an external server remote from the PIM, the external server including a server wireless transceiver configured to communicate with the PIM wireless transceiver to receive the wirelessly transmitted processed image signal.

3. The system of claim 1 or claim 2, further comprising plural power supply rails extending through the IVUS catheter electrically connecting the distal tip micropulser and PIM to deliver a DC voltage from the battery to energize the distal tip micropulser.

4. The system of claim 3, wherein the DC voltage delivered by the battery to the distal tip micropulser does not exceed about 5 VDC.

5. The system of claim 4, wherein the DC voltage delivered by the battery to the distal tip micropulser does not exceed about 3 VDC.

6. The system of claim 3, wherein the power supply rails comprise: a catheter supply rail that powers the distal tip microcontroller, delivering voltage of about 2 VDC to 5 VDC; and an impulse generator supply rail that provides impulse power to the transducer, delivering DC power at current levels of up to about 450 mA.

7. The system of claim 6, wherein the catheter supply rail delivers DC voltage in a range of about2.45 VDC to 3.0VDC, and the impulse generator supply rail delivers DC power at a current level of up to about 330 mA.31 Attorney Docket No. 19275-005WOU18. The system of any of claims 1-7, wherein the PIM microcontroller processing of the imaging signal comprises lossless compression.

9. The system of claim 8, wherein the PIM microcontroller processing of the image signal further comprises wavelet transform reducing the signal sampling rate requirement by about 5-10 times prior to the lossless compression.

10. The system of any of claims 1-9, further comprising an inductive power coupling coil within the PIM allowing inductive charging of the battery11. The system of claim 10, further comprising an external inductive power coupling pad including an inductive charging coil configured for charging the battery when the PIM is placed within a preset inductive power coupling range of the inductive power coupling pad.

12. The system of claim 11, wherein the inductive power coupling pad is configured as a part of the server.

13. The system of claim 12, wherein the server is positioned on or integrated into an angiography system table.

14. The system of any of claims 1-13, wherein the power required by the IVUS catheter and supplied by the battery does not exceed about 5 uW.

15. The system of claim 14, wherein the power required by the IVUS catheter and supplied by the battery does not exceed about 1 uW.

16. The system of any of claims 1-15, wherein the PIM comprises: a user actuatable abort logic through which all battery power is routed; a pulser power supply receiving power from the abort logic and supplying power to the catheter supply rail and impulse generator supply rail; and a control power supply receiving power from the abort logic and supplying power to the microcontroller; a hardware supervisory section comprising discrete circuits configured to monitor power usage in each electrically powered component of the PIM to ensure power usage does not exceed preset limits.

17. The system of any of claims 1-16, wherein: the IVUS catheter includes a rotating core; the distal micropulser is mounted on the rotating core;32 Atorney Docket No. 19275-005WOU1the PIM includes a rotational drive operatively connected to the rotating core and powered by the battery through a rotational drive power supply; and the PIM microcontroller is configured to control the rotational drive.

18. The system of claim of claim 17, wherein the rotational drive is monitored by the hardware supervisory section and the PIM microcontroller to provide an emergency shut off in the event of a rotational drive motor overspeed or over current condition.

19. The system of any of claims 1-18, wherein: the IVUS catheter includes a translatable core; the distal micropulser is mounted on the translatable core; the PIM includes a translation drive operatively connected to the translatable core and powered by the battery through a translational drive power supply; and the PIM microcontroller is configured to control the translational drive.

20. The system of any of claims 1-19, wherein the PIM includes a PIM user interface.

21. The system of any of claims 2-20, wherein the IVUS catheter, PIM and external server are integrated into an angiography suite further comprising an integrated x-ray system, an angiography table, and integrated display.

22. The system of claim 21, wherein the external server is integrated into the angiography table and includes an inductive power coupling pad for inductive charging of the PIM battery.

23. An angiography system including IVUS imaging, comprising: an angiography table; an external patient imaging system; an angiography console including a display configured to present images from the external patient imaging system and IVUS imaging, a wireless transceiver and an IVUS server; an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; a patient interface module (PIM) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM wireless transceiver and the distal tip micropulser, a battery configured to power the PIM and the distal tip micropulser and an inductive power coupling coil for remotely charging33 Atorney Docket No. 19275-005WOU1the battery, wherein the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission and the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal to wireless transceiver of the angiography console; and an inductive power coupling pad including a power coupling coil disposed on or integrated into the angiography table.

24. The system of claim 23, wherein: the IVUS catheter includes a rotating core; the distal micropulser is mounted on the rotating core; the PIM includes a rotational drive operatively connected to the rotating core and powered by the battery through a rotational drive power supply; and the PIM microcontroller is configured to control the rotational drive.

25. The system of claim 23 or claim 24, further comprising plural power supply rails extending through the IVUS catheter electrically connecting the distal tip micropulser and PIM to deliver a DC voltage from the battery to energize the distal tip micropulser.

26. The system of claim 25, wherein the power supply rails comprise: a catheter supply rail that powers the distal tip microcontroller, delivering voltage of about 2 VDC to 5 VDC; and an impulse generator supply rail that provides impulse power to the transducer, delivering DC power at current levels of up to about 450 mA.

27. A wireless intravascular ultrasound (IVUS) imaging system, comprising: an IVUS catheter with a proximal end and a distal end, the distal end including a distal tip micropulser including a microcontroller and transducer configured to generate high frequency ultrasound imaging pulses at the distal end of the catheter, receive reflected imaging pulses and generate an imaging signal; a catheter supply rail extending though the IVUS catheter to provide power to the distal tip microcontroller; an impulse generator supply rail extending through the IVUS catheter to provide impulse power to the transducer; a patient interface module (PIM) connected to the proximal end of the IVUS catheter, the PIM comprising a PIM wireless transceiver, a PIM microcontroller communicating with the PIM34 Atorney Docket No. 19275-005WOU1wireless transceiver and the distal tip micropulser, and a battery configured to power the PIM and the distal tip micropulser, wherein - the PIM delivers a voltage of about 2 VDC to 5 VDC to the distal tip microcontroller via the catheter supply rail; the PIM delivers DC power at current levels of up to about 450 mA via the impulse generator supply rail to drive the distal tip transducer; the PIM microcontroller is configured to receive the imaging signal from the distal tip micropulser and process the imaging signal for wireless transmission; the PIM wireless transceiver is configured to wirelessly transmit the processed imaging signal; and an external server remote from the PIM, the external server including a server wireless transceiver configured to communicate with the PIM wireless transceiver to receive the wirelessly transmitted processed image signal.

28. The system of claim 27, wherein the PIM microcontroller processing of the imaging signal comprises wavelet transform reducing the signal sampling rate requirement by about 5-10 times followed by lossless compression before wirelessly transmitting the signal to the server wireless transceiver.

29. The system of claim 28, further comprising an inductive power coupling coil within the PIM allowing inductive charging of the battery.

30. The system of any of claims 27-29, wherein: the IVUS catheter includes a rotating core; the distal micropulser is mounted on the rotating core; the PIM includes a rotational drive operatively connected to the rotating core; and the PIM microcontroller is configured to control the rotational drive.

31. The system of claim 30, wherein the PIM comprises: a user actuatable abort logic through which all battery power is routed; a pulser power supply receiving power from the abort logic and supplying power to the catheter supply rail and impulse generator supply rail; a control power supply receiving power from the abort logic and supplying power to the microcontroller; a rotational drive power supply receiving power from the abort logic and supplying power to rotational drive; and35 Atorney Docket No. 19275-005WOU1a hardware supervisory section comprising discrete circuits configured to monitor power usage in each electrically powered component of the PIM to ensure power usage does not exceed preset limits.

32. The system of any of claims 23-31, wherein the power required by the IVUS catheter and supplied by the battery does not exceed about 5 uW.36 Atorney Docket No. 19275-005WOU1

Images