Ultrasound imaging catheter

Abstract

The ultrasound imaging catheter has an ultrasound transducer array provided at a distal end of the ultrasound imaging catheter. The ultrasound transducer array has a plurality of ultrasound transducers for transmitting and receiving ultrasound signals. The ultrasound imaging catheter includes a local memory provided at the distal end of the ultrasound imaging catheter. The local memory stores a plurality of activation patterns, each activation pattern corresponding to some transducer elements to be activated and some transducer elements to be deactivated. The ultrasound imaging catheter includes a control unit provided at the distal end of the ultrasound imaging catheter. The control unit accesses the local memory, selects any one of the plurality of activation patterns, and generates control signals for activating or deactivating the plurality of transducer elements of the transducer array according to the selected activation pattern during an imaging phase of the ultrasound imaging catheter.

Description

Technical Field

[0001] The present invention relates to the field of ultrasonic imaging systems, and more particularly to ultrasonic imaging catheters.

Background Art

[0002] Intravascular ultrasonic imaging catheters are widely used in many different clinical applications. Typically, an ultrasonic imaging catheter is fully controlled from a backend processing unit or console. For each ultrasonic transducer element within the ultrasonic imaging catheter, it is necessary to determine whether the transducer element is active during the transmission of an ultrasonic pulse and whether the transducer element should be active during the reception of an echo from the transmitted pulse.

[0003] Attempts have been made to increase the number of transducer elements that can be placed at the tip of the catheter in order to improve the imaging quality of the ultrasonic imaging catheter.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Increasing the number of transducer elements and increasing the number of return channels for echoes results in significant problems such as steep signal slopes and high bandwidth requirements, which in turn leads to an increased burden on the communication between the console and the catheter.

[0005] Typically, the communication channels in an ultrasonic imaging catheter system are composed of wires with relatively high resistance and capacitance due to mechanical requirements, which cause interference to the communication signal and reduce the accuracy of the image generated by the ultrasonic imaging catheter.

[0006] Therefore, an improved means of handling communication between the ultrasound imaging catheter and the control console is needed. [Means for solving the problem]

[0007] The present invention is defined by the claims.

[0008] According to an example of an aspect of the present invention, an ultrasound imaging catheter is provided, and the ultrasound imaging catheter is An ultrasonic transducer array provided at the distal end of an ultrasonic imaging catheter and configured to transmit and receive ultrasonic signals, comprising a plurality of ultrasonic transducers, A local memory provided at the distal end of an ultrasound imaging catheter configured to store multiple activation patterns, wherein each activation pattern corresponds to several transducer elements to be activated and several transducer elements to be deactivated, and the local memory comprises: Access local memory, Select any one of the multiple launch patterns, During the imaging phase of an ultrasound imaging catheter, control signals are generated to activate or deactivate multiple transducer elements of a transducer array according to a selected activation pattern, and the imaging phase has a transmission period and a reception period. A control unit is provided at the distal end of an ultrasound imaging catheter, configured as follows: It has.

[0009] In this way, the functionality of the front end of the ultrasound imaging catheter may be increased, thereby reducing the amount of communication required between the front end and the back-end processing unit, and thereby providing a means to achieve a higher frame rate, a higher number of transducer elements in the transducer array, and a higher number of echo return channels. In one embodiment, the ultrasound imaging catheter is Multiple registers, each register having multiple bits, and each bit being associated with an ultrasonic transducer among multiple ultrasonic transducers, A local oscillator configured to communicate with multiple registers, receive control signals generated by a control unit, and manipulate multiple bits in the multiple registers to start and / or stop multiple transducer elements of a transducer array according to a selected start pattern, It also has.

[0010] In this way, the asynchronous communication scheme may be implemented at the front end of the ultrasound imaging catheter, otherwise a free-running clock signal would be required to provide an extra signal edge to initiate register operation.

[0011] In one embodiment, the local oscillator is configured to operate outside the imaging phase of the ultrasound imaging catheter.

[0012] In this way, potential imaging artifacts caused by signal feedthrough or crosstalk from the local oscillator can be avoided.

[0013] According to one embodiment, the local oscillator is configured to operate at a frequency greater than the bandwidth of the multiple ultrasonic transducers.

[0014] In this way, image artifacts caused by the local oscillator may be reduced or eliminated.

[0015] According to one embodiment, the local oscillator is configured to generate a square wave having a predetermined duty cycle. The duty cycle is such that the components of the local oscillator's frequency spectrum are outside the bandwidth of the multiple ultrasonic transducers.

[0016] In this way, the harmonics of the local oscillator are placed outside the bandwidth of the ultrasonic transducer, thereby reducing any imaging artifacts caused by the local oscillator.

[0017] In one embodiment, a plurality of registers are configured into a plurality of register groups, and each register group includes a first register having a first register bit, a second register having a second register bit, and having a first register bit configured to control whether the transducer element is activated or deactivated during the transmission period, and a second register bit configured to control whether the transducer element is activated or deactivated during the reception period, and the transducer element among the plurality of transducer elements is associated with the first register bit and the second register bit.

[0018] By providing individual registers for each function, greater flexibility in the activation pattern and its application may be achieved.

[0019] In a further embodiment, the ultrasonic transducer array has a plurality of output channels, each register group further includes a third register having a third register bit, the transducer element is further associated with the third register bit, and the third register bit is configured to control to which of the plurality of output channels the signal received in the transducer element is output.

[0020] [[ID=2l]] In one embodiment, the plurality of register groups are connected in a daisy chain, and each register group is connected in series with an adjacent register group.

[0021] [ In this way, the number of connections required for the catheter front end can be reduced without adversely affecting the functionality of the ultrasonic imaging catheter.

[0022] In one embodiment, the ultrasonic imaging catheter further includes a signal conditioning unit provided at the distal end of the ultrasonic imaging catheter and configured to apply signal conditioning to the received ultrasonic signals.

[0023] In this way, the signals can be conditioned before being sent to the back-end processing unit, thereby reducing imaging artifacts that can be enhanced during transmission, and as a result, improving the accuracy of the final ultrasonic image.

[0024] In a further embodiment, the signal conditioning unit includes a low-noise amplifier.

[0025] According to one embodiment, the signal conditioning unit includes one or more time gain compensation units.

[0026] According to an example according to one aspect of the present invention, an ultrasonic imaging system is provided, the system comprising an ultrasonic imaging catheter as described above, a processing unit configured to communicate with the ultrasonic imaging catheter and generate an ultrasonic image based on the received ultrasonic signals, and a display configured to display the ultrasonic image. and having.

[0027] According to an example according to one aspect of the present invention, a method of controlling an ultrasonic imaging catheter having an ultrasonic transducer array having a plurality of ultrasonic transducers is provided, the method comprising accessing a local memory provided at the distal end of the ultrasonic imaging catheter; selecting any one of a plurality of activation patterns stored in the local memory, each activation pattern corresponding to some of the transducer elements to be activated and some of the transducer elements to be deactivated among the plurality of transducer elements. A step of generating control signals to activate or deactivate multiple transducer elements of a transducer array according to a selected activation pattern during the imaging phase of an ultrasound imaging catheter, wherein the imaging phase comprises a transmission period and a reception period. It has.

[0028] In one embodiment, the method further includes: The steps include providing a control signal to a local oscillator, A step of manipulating multiple bits of multiple registers, wherein each bit is associated with an ultrasonic transducer among multiple ultrasonic transducers in order to start and / or stop multiple transducer elements of a transducer array according to a selected start pattern, It has.

[0029] According to one aspect of the present invention, a computer program is provided having computer program code means configured to perform the above-described method when the computer program is executed on a computer.

[0030] These and other aspects of the present invention will become apparent from and be explained with reference to the embodiments described below.

[0031] To better understand the present invention and to more clearly illustrate how it can be implemented, the accompanying drawings are referenced here, merely as examples. [Brief explanation of the drawing]

[0032] [Figure 1] This shows an ultrasound diagnostic imaging system to illustrate its general operation. [Figure 2] A schematic representation of an ultrasound imaging catheter is shown. [Figure 3] A more detailed schematic representation of the ultrasound imaging catheter shown in Figure 2 is provided below. [Figure 4] Some examples of ultrasound imaging catheters are shown. [Figure 5] An example of a register connection scheme is shown. [Figure 6] This shows a general representation of the register related to catheters. [Figure 7] The present invention demonstrates the method. [Modes for carrying out the invention]

[0033] The present invention will be described with reference to the drawings.

[0034] The detailed descriptions and specific examples illustrate exemplary embodiments of the apparatus, system, and method, but should be understood to be for illustrative purposes only and not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, system, and method of the invention will be better understood from the following description, the appended claims, and the appended drawings. The drawings are for illustrative purposes only and are not drawn to a specific scale. Also, the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0035] The present invention provides an ultrasound imaging catheter having an ultrasound transducer array provided at the distal end of the ultrasound imaging catheter and configured to transmit and receive ultrasound signals, wherein the ultrasound transducer array has a plurality of ultrasound transducers. The ultrasound imaging catheter further includes a local memory provided at the distal end of the ultrasound imaging catheter and configured to store a plurality of activation patterns, each activation pattern corresponding to a plurality of transducer elements to be activated and a plurality of transducer elements to be deactivated. In addition, the ultrasound imaging catheter includes a control unit provided at the distal end of the ultrasound imaging catheter and configured to access the local memory, select any one of the plurality of activation patterns, and generate control signals to activate or deactivate the plurality of transducer elements of the transducer array according to the selected activation pattern during the imaging phase of the ultrasound imaging catheter, the imaging phase having a transmit period and a receive period.

[0036] The general operation of an exemplary ultrasonic system will first be explained with reference to Figure 1.

[0037] The system has an array transducer probe 4 having a transducer array 6 for transmitting ultrasound and receiving echo information. The transducer array 6 may have CMUT transducers, piezoelectric transducers formed from materials such as PZT or PVDF, polymer-based transducers, or any other suitable transducer technology. In this example, the transducer array 6 is a two-dimensional array of transducers 8 that can scan either a two-dimensional plane or a three-dimensional volume of the region of interest. In another example, the transducer array may be a one-dimensional array.

[0038] The transducer array 6 is coupled to a microbeamformer 12 that controls the reception of signals by the transducer elements. The microbeamformer can at least partially beamform the signals received by the subarray, which are generally referred to as “groups” or “patches” of transducers, as described in U.S. Patents No. 5,997,479 (Savord et al.), No. 6,013,032 (Savord), and No. 6,623,432 (Powers et al.).

[0039] Note that the microbeamformer is entirely optional. Furthermore, the system includes a transmit / receive (T / R) switch 16 to which a microbeamformer 12 can be coupled, switching the array between transmit and receive modes and protecting the main beamformer 20 from high-energy transmit signals when the microbeamformer is not used and the transducer array is operated directly by the main system beamformer. The transmission of the ultrasonic beam from the transducer array 6 is directed by a transducer controller 18 coupled to the microbeamformer via the T / R switch 16 and a main transmit beamformer (not shown), and the main transmit beamformer can receive input from user operation on the user interface or control panel 38. The controller 18 may include a transmit circuit configured to drive the transducer elements of array 6 (either directly or via the microbeamformer) during transmit mode.

[0040] In a typical line-by-line imaging sequence, the beamforming system within the probe may operate as follows: During transmission, the beamformer (which may be a microbeamformer or main system beamformer, depending on the implementation) activates a transducer array or a sub-aperture of the transducer array. The sub-aperture may be a one-dimensional line of transducers or a two-dimensional patch of transducers in a larger array. In transmission mode, the focusing and traversal of the ultrasonic beam generated by the array or sub-aperture of the array are controlled as described below.

[0041] Upon receiving a backscattered echo signal from the target, the received signal undergoes received beamforming (as described below) to align the received signal, and if a sub-aperture is used, the sub-aperture is shifted, for example, by one transducer element. The shifted sub-aperture is then activated, and this process is repeated until all transducer elements in the transducer array are activated.

[0042] For each line (or sub-aperture), the total received signal used to form the relevant line in the final ultrasound image is the sum of the voltage signals measured by the transducer element of a given sub-aperture during the reception period. The line signals obtained following the beamforming process are typically referred to as radio frequency (RF) data. Each line signal (RF data set) generated by the various sub-apertures then undergoes additional processing to generate the lines in the final ultrasound image. The change in amplitude of the line signal over time contributes to the change in brightness of the ultrasound image over depth, with high-amplitude peaks corresponding to bright pixels (or clusters of pixels) in the final image. Peaks appearing near the beginning of the line signal represent echoes from shallow structures, while peaks appearing later in the line signal represent echoes from structures at increasing depths within the object.

[0043] One of the functions controlled by the transducer controller 18 is the direction in which the beam is steered and focused. The beam may be steered straight (orthogonal) from the transducer array, or at different angles for a wider field of view. The steer and focusing of the transmit beam may be controlled as a function of the transducer element activation time.

[0044] Two methods, namely plane-wave imaging and "beam-manipulation" imaging, can be distinguished in general ultrasound data acquisition. The two methods are distinguished by the presence of beamforming in the transmission mode ("beam-manipulation" imaging) and / or the reception mode (plane-wave imaging and "beam-manipulation" imaging).

[0045] First, looking at the focusing function, by activating all transducer elements simultaneously, the transducer array generates a plane wave that diverges as it moves through the target. In this case, the ultrasonic beam remains unfocused. By introducing a position-dependent time delay in the activation of the transducers, it is possible to focus the wavefront of the beam at a desired point called the focal zone. The focal zone is defined as the point where the lateral beamwidth is less than half the transmit beamwidth. In this way, the lateral resolution of the final ultrasonic image is improved.

[0046] For example, if a time delay causes the transducer elements to be activated in a sequence starting at the outermost elements of the transducer array and ending at the central element(s), the focal zone will be formed in a straight line with the central element(s) at a given distance from the probe. The distance of the focal zone from the probe varies depending on the time delay between each subsequent round of transducer element activation. After passing through the focal zone, the beam begins to diverge, forming the far-field imaging region. Note that for focal zones located close to the transducer array, the ultrasound beam diverges rapidly in the far-field, resulting in beam width artifacts in the final image. Typically, the near-field, located between the transducer array and the focal zone, shows little detail due to significant overlap in the ultrasound beam. Therefore, changing the position of the focal zone can result in significant changes in the quality of the final image.

[0047] Note that in transmission mode, only one focal point can be defined unless the ultrasound image is divided into multiple focal zones (each potentially having a different transmission focus).

[0048] In addition, upon receiving an echo signal from within the target, it is possible to perform the reverse of the above process to perform receive focusing. In other words, the incoming signal may undergo an electronic time delay before being received by the transducer element and passed to the system for signal processing. The simplest example of this is called delayed sum beamforming. It is possible to dynamically adjust the receive focusing of the transducer array as a function of time.

[0049] Looking at the beam manipulation function, it is possible to impart a desired angle to the ultrasonic beam as it leaves the transducer array through the correct application of time delays to the transducer elements. For example, by activating the transducers on the first side of the transducer array and then activating the remaining transducers in a sequence that ends on the opposite side of the array, the wavefront of the beam can be angled toward the second side. The magnitude of the manipulation angle relative to the normal of the transducer array depends on the magnitude of the time delay between the activations of the subsequent transducer elements.

[0050] Furthermore, the controlled beam can be focused, where the total time delay applied to each transducer element is the sum of the focusing time delay and the control time delay. In this case, the transducer array is referred to as a phased array.

[0051] For CMUT transducers that require a DC bias voltage for their activation, the transducer controller 18 can be coupled to control a DC bias control unit 45 for the transducer array. The DC bias control unit 45 sets the (multiple) DC bias voltages applied to the CMUT transducer elements.

[0052] For each transducer element in the transducer array, an analog ultrasonic signal, typically referred to as channel data, enters the system via a receiving channel. In the receiving channel, a partially beamformed signal is generated from the channel data by a microbeamformer 12 and then passed to a main receiving beamformer 20, where the partially beamformed signals from individual patches of transducers are combined into a fully beamformed signal, referred to as radio frequency (RF) data. The beamforming performed at each stage may be carried out as described above, or may include additional functions. For example, the main beamformer 20 may have 128 channels, each receiving partially beamformed signals from patches of dozens or hundreds of transducer elements. In this way, the signals received by thousands of transducers in the transducer array can efficiently contribute to a single beamformed signal.

[0053] The beamformed received signal is coupled to the signal processor 22. The signal processor 22 can process the received echo signal in various ways, such as band-pass filtering, decimation, I and Q component separation, and harmonic signal separation, which act to separate linear and nonlinear signals so as to enable identification of nonlinear (higher harmonics of the fundamental frequency) echo signals returned from tissue and microbubbles. The signal processor may also perform additional signal enhancements such as speckle reduction, signal compounding, and denoising. The band-pass filter within the signal processor may be a tracking filter, whose passband slides from a higher frequency band to a lower frequency band as the echo signal is received from a greater depth, thereby eliminating noise at higher frequencies from greater depths that typically lack anatomical information.

[0054] Beamformers for transmission and reception can be implemented with different hardware and have different functions. Of course, receiver beamformers are designed taking into account the characteristics of the transmission beamformer. In Figure 1, only receiver beamformers 12 and 20 are shown for simplification. In a complete system, there would also be a transmission chain with a transmission microbeamformer and a main transmission beamformer.

[0055] The function of the microbeam former 12 is to provide an initial combination of signals to reduce the number of analog signal paths. This is typically done in the analog domain.

[0056] The final beamforming takes place in the main beamformer 20, typically after digitization.

[0057] The transmit and receive channels use the same transducer array 6 with a fixed frequency bandwidth. However, the bandwidth occupied by the transmit pulse can vary depending on the transmit beamforming used. The receive channel can capture the entire transducer bandwidth (this is a classical approach), or by using band-pass processing, only the bandwidth containing the desired information (e.g., harmonics of the main harmonics) can be extracted.

[0058] The RF signal can then be coupled to a B-mode (i.e., luminance mode, or 2D imaging mode) processor 26 and a Doppler processor 28. The B-mode processor 26 performs amplitude detection on the received ultrasound signal for imaging of internal structures such as organ tissues and blood vessels. In line-by-line imaging, each line (beam) is represented by an associated RF signal whose amplitude is used to generate a luminance value to be assigned to a pixel in the B-mode image. The precise location of the pixel in the image is determined by the location of the associated amplitude measurement along the RF signal and the number of lines (beams) of the RF signal. B-mode images of such structures may be formed in harmonic or fundamental wave image modes, or a combination of both, as described in U.S. Patent No. 6,283,919 (Roundhill et al.) and U.S. Patent No. 6,458,083 (Jago et al.). The Doppler processor 28 processes temporally distinct signals resulting from tissue movement and blood flow for the detection of moving substances such as blood cell flow in the image field. The Doppler processor 28 typically includes a wall filter with parameters set to allow or reject echoes returned from a selected type of material within the body.

[0059] The structure and motion signals generated by the B-mode and Doppler processors are coupled to the scan converter 32 and the multi-planar reformatter 44. The scan converter 32 arranges the echo signals in the spatial relationships of the received image in the desired image format. In other words, the scan converter acts to convert the RF data from a cylindrical coordinate system to a Cartesian coordinate system suitable for displaying the ultrasound image on the image display 40. In the case of B-mode imaging, the brightness of a pixel at a given coordinate is proportional to the amplitude of the RF signal received from that position. For example, the scan converter may arrange the echo signals in a two-dimensional (2D) sector or pyramidal three-dimensional (3D) image. The scan converter can overlay a color corresponding to the motion at a point in the image field onto the B-mode structure image, where the Doppler estimated velocity generates the given color. The combined B-mode structure image and color Doppler image depict the movement of tissue and blood flow within the structure image field. The multi-plane reformatter converts echoes received from a point in a common plane within a volume region of the body into an ultrasound image of that plane, as described in U.S. Patent No. 6,443,896 (Detmer). The volume renderer 42 converts the echo signals of a 3D dataset into a projected 3D image viewed from a given reference point, as described in U.S. Patent No. 6,530,885 (Entrekin et al.).

[0060] 2D or 3D images are coupled from the scan converter 32, multi-planar reformatter 44, and volume renderer 42 to the image processor 30 for further enhancement, buffering, and temporary storage for display on the image display 40. The imaging processor may be configured to remove certain imaging artifacts from the final ultrasound image, such as acoustic shadows caused by strong attenuation or refraction, back emphasis caused by weak attenuation, and reverberation artifacts when highly reflective tissue interfaces are located in close proximity. In addition, the image processor may be configured to handle certain speckle reduction functions to improve the contrast of the final ultrasound image.

[0061] In addition to being used for imaging, blood flow values ​​generated by the Doppler processor 28 and tissue structure information generated by the B-mode processor 26 are combined with the quantification processor 34. The quantification processor generates measurements of different flow states, such as the volume velocity of blood flow, in addition to structural measurements such as organ size and gestational age. The quantification processor may also receive input from the user control panel 38, such as points within the anatomical structures of the image on which measurements are to be taken.

[0062] The output data from the quantification processor is coupled to the graphics processor 36 for the reproduction of measurement graphics and values ​​using images on the display 40, and for audio output integrated into the display device 40. The graphics processor 36 can also generate graphic overlays for display with the ultrasound images. These graphic overlays may include standard identification information such as patient name, date and time of image, and imaging parameters. For these purposes, the graphics processor receives input such as patient name from the user interface 38. The user interface is also coupled to the transmit controller 18 to control the generation of ultrasound signals from the transducer array 6, and therefore the generation of images generated by the transducer array and ultrasound system. The transmit control function of the controller 18 is only one of the functions it performs. The controller 18 also considers the operating mode (provided by the user) and the corresponding required transmitter and bandpass settings in the receiver analog-to-digital converter. The controller 18 can be a state machine with fixed states.

[0063] The user interface is also coupled to a multiplanar reformatter 44 for the selection and control of multiple multiplanar reformat (MPR) images, which can be used to perform quantified measurements in the image field of the MPR images.

[0064] Figure 2 shows a schematic representation 100 of the ultrasound imaging catheter 110.

[0065] The ultrasound imaging catheter 110 has an ultrasound transducer array 120 provided at the distal end of the ultrasound imaging catheter, which has a plurality of ultrasound transducers 125.

[0066] The ultrasound imaging catheter 110 further includes a local memory (LM) 130 located at the distal end of the ultrasound imaging catheter, which is configured to store multiple activation patterns. Each of the multiple activation patterns corresponds to several transducer elements 125a to be activated and several transducer elements 125b to be deactivated from among the multiple transducer elements during the imaging phase of the ultrasound imaging catheter.

[0067] The imaging phase may be considered as two separate periods: a transmission period in which an ultrasonic signal is generated by an ultrasonic transducer and transmitted into the target, and a reception period in which the echo from the transmitted ultrasonic transducer is received by the ultrasonic transducer.

[0068] In addition, the ultrasound imaging catheter 110 has a control unit (CU) 140 located at the distal end of the ultrasound imaging catheter, which is configured to access local memory and select any one of a plurality of activation patterns stored in the local memory.

[0069] Next, the control unit generates control signals 150 to start or stop multiple transducer elements of the transducer array according to the selected activation pattern. In the example shown in Figure 2, the LM130 is operated by the CU140 to pass the control signals 150 to the transducers, thereby controlling the activity of the transducers. The CU140 also functions as a communication link between the circuit at the distal end of the ultrasound imaging catheter 110 and the rest of the ultrasound system.

[0070] By placing the local memory 130 and the control unit 140 in the catheter rather than in the backend processing unit, the necessary communication between the backend console and the catheter is reduced.

[0071] In other words, motion control functions can be added to the catheter to independently perform at least some of the operations in transmitting element selection, receiving element selection, and / or return channel selection. This results in a significantly reduced communication requirement between the console and the catheter, allowing for higher frame rates, more ultrasound transducer elements, and more echo return channels to be employed in the system.

[0072] The ultrasound imaging catheter may function as the ultrasound probe 4 described above, as shown in Figure 1.

[0073] Figure 3 shows a more detailed schematic representation 200 of the ultrasound imaging catheter 110 shown in Figure 2.

[0074] In the example shown in Figure 3, the ultrasound imaging catheter 110 is shown having two component groups, namely a digital section 210 and an analog section 220.

[0075] The digital unit 210 includes a two-wire serial interface (SI) 230 that can communicate with, for example, a console for controlling the ultrasound imaging catheter 110 or any other suitable backend processing unit. Signals may also be provided via the serial interface to a parameter control unit (P) 240 configured to set and read back parameters for controlling the operation of both the analog unit 220 and the digital unit 210 of the ultrasound imaging catheter.

[0076] The digital unit 210 further includes a transducer selection unit (TSU) 250 which may have the local memory 130 and control unit 140 described above, as shown in Figure 2.

[0077] The transducer selection unit determines which transducer elements of the transducer array 120 should be active during the transmission period and which transducer elements should be used during the reception period. This is done by the control unit accessing local memory and retrieving one of several activation patterns.

[0078] In the example shown in Figure 3, the transducer selection unit generates a control signal 255, which is provided to the driver unit (D) 260 and the receiver unit (R) 270. The driver unit activates the ultrasonic transducers of the transducer array during the transmission period according to the control signal received from the transducer selection unit. Similarly, the receiver unit activates the ultrasonic transducers of the transducer array during the reception period according to the control signal received from the transducer selection unit.

[0079] In other words, the transducers of the ultrasound transducer array are activated according to control signals generated by a transducer selection unit, based on an activation pattern, during the transmission and reception periods of the imaging phase.

[0080] In other words, the transducer elements of the transducer array located at the distal end of the ultrasound imaging catheter are activated based on an activation pattern stored in a local memory located at the distal end.

[0081] During the transmission phase, the ultrasound transducer selected as active according to the activation pattern is operated to generate ultrasound pulses, for example, when the ultrasound imaging catheter is positioned inside the target, such as inside a target blood vessel.

[0082] During the receiving phase, the ultrasound transducer receives echo signals 290 from the subject's body. The received echo signals may undergo signal conditioning before being sent to the backend processing system as appropriate.

[0083] In the example shown in Figure 3, the analog portion 220 of the ultrasound imaging catheter 110 has a low-noise amplifier 300 to adjust the incoming received echo signal; however, any other signal adjustment unit, such as a time-gain compensation unit, may be implemented in the analog portion.

[0084] The adjusted signal is then passed to a signal selector (SS) 310, which may apply selection criteria to the adjusted signal to determine which signals can be sent to backend processing to generate an ultrasound image. The selection criteria may include, for example, a given measure of signal quality, such as the signal-to-noise ratio. The selection criteria may be adjusted, for example, by user input, depending on the application of the ultrasound imaging catheter.

[0085] When the transducer selection unit receives signal 320 to initiate the "Give Next Acquisition" command, i.e., the command to start the subsequent imaging phase, the transducer selection unit determines the transducers to be used for the next imaging operation as transmitting and receiving elements. More specifically, the command may cause the control unit to access local memory to select the activation pattern corresponding to the transducers to be activated or deactivated.

[0086] Figure 4 shows an exemplary embodiment 400 of the digital portion 210 of the ultrasound imaging catheter shown in Figure 3.

[0087] In the example shown in Figure 4, the intelligence level of the transducer selection unit is slightly reduced compared to the example described with respect to Figure 3. As a result, the communication requirements between the backend processing unit or console and the ultrasound imaging catheter may increase slightly, but the communication requirements are still significantly reduced compared to a standard ultrasound imaging catheter. However, this example may offer more flexibility in determining which ultrasound elements to activate or deactivate during the transmission and reception periods. Furthermore, this example may increase the flexibility of return channel selection for transmitting the received echo signal to the backend processing system.

[0088] The example shown in Figure 4 operates using two communication mechanisms. The first communication interface 410 is a serial interface for setting and reading parameters for both the analog and digital portions of the ultrasound imaging catheter, as described above with reference to Figure 3. The serial interface operates based on two signals: a serial clock (SCL) signal and a serial data (SDA) signal. I 2 C It may be connected to interface 420.

[0089] The second communication interface 430 may have a high-speed serial (HS) interface 440, which is a one-way equivalent of the “give next acquisition” instruction described above with respect to Figure 3.

[0090] Figure 4 shows several dies placed inside an ultrasound imaging catheter, namely one master die 450 and multiple slave dies 460. I 2 C The first communication interface 410, which may include interface 420, may be implemented to be the same for all dies. The die type, master die 450 or slave die 460, is I <superscript> 2< / superscript> This may be determined by three address pins on the C interface unit. If the address pins indicate "000", the die is considered to be the master die 450. On the other hand, if the address pins indicate a value between "001" and "111", the die is considered to be the slave die 460. In this example, the maximum allowed number of slave dies 460 is 7, however, the number of slave dies may be increased or decreased depending on the application.

[0091] Slave die 460 I 2 CThe interface unit 420 may be connected to an analog circuit, which may not only connect the slave unit 470 to each slave die 460 but also include components such as a low-noise amplifier (LNA) and / or time-gain compensation (TGC), as described above with reference to Figure 3. The slave unit 470 is part of a circuit that provides each ultrasonic transducer 480 with instructions on whether to be active or inactive during transmission and reception, and on which output channel the received echo signal should be placed.

[0092] In the example shown in Figure 4, each slave die 260 can address up to 24 individual transducers 280, the information relating to which transducer elements are active during the transmission period, which transducer elements are active during the reception period, and which output channel the received echo signal is supplied to so that it is held on three 24-bit registers. Thus, a catheter having up to 168 transducer elements may be configured according to this embodiment using up to seven slaves.

[0093] The first communication interface 410 and the second communication interface 430 are completely asynchronous, meaning that the clock edges of the communication protocol itself are used to register the data. In other words, there is no free-running clock in the catheter that can be used to sample the communication interfaces. For several reasons, such as electromagnetic compatibility (EMC) and potential image artifacts, it may be advantageous not to have a free-running clock in the catheter during the imaging phase. Since the number of clock edges in the two communication interfaces matches the data being transferred, there are no extra edges available for the HS interface 440 to manipulate the information in the slave unit's registers and therefore for applying the information contained in the application pattern to the ultrasound transducer 480.

[0094] Therefore, the ultrasound imaging catheter may further include a local oscillator (LO) 490 configured to communicate with multiple registers, receive control signals generated by a control unit, and manipulate multiple bits in the multiple registers to start and / or stop multiple transducer elements of a transducer array according to a selected activation pattern.

[0095] The local oscillator 490 may be located on a master die 450, which can be initiated by an HS unit 440 to perform the necessary operations on the register. The operation of the register by the HS unit, and therefore the operation of the local oscillator, occurs only outside the imaging phase, thereby preventing potential image artifacts, for example, due to local oscillator feedthrough or crosstalk. Another mechanism employed to prevent image artifacts by the local oscillator is to ensure that the lowest frequency of the local oscillator is higher than the bandwidth of the ultrasonic transducer 480. The local oscillator may be configured to generate a square wave with a given duty cycle in order to bring the harmonics of the local oscillator outside the bandwidth of the ultrasonic transducer. For example, the duty cycle may be 50% or 60%, or in practice, any appropriate duty cycle that ensures that the spectral components of the oscillator are outside the bandwidth of the multiple ultrasonic transducers.

[0096] Figure 5 shows an example of interconnection between registers 510 of different slave units 470 on a slave die 460. Each register has multiple bits, each bit associated with one of several ultrasound transducers in the transducer array of an ultrasound imaging catheter.

[0097] In the example shown in Figure 5, each slave unit 470 has three registers 510, which include a transmit register Tx configured to control which of the associated transducer elements is activated or deactivated during the transmit period, a receive register Rx configured to control which of the associated transducer elements is activated or deactivated during the receive period, and an output channel register Rxmap configured to control which of the multiple output channels the signal received by the transducer element is output to. In this case, a given transducer element is associated with one bit from each of the three registers of a given slave unit.

[0098] To limit the amount of connectivity required between slave dies, the registers for transmit (Tx), receive (Rx), and mapping to output channels (Rxmap) may be connected to the next die via a single connection.

[0099] A single connection between dies, also known as a daisy-chain connection, means that the operations of the transmit register, receive register, and output channel register must be performed sequentially.

[0100] To select the appropriate number of transducer elements, there are two available methods: one for selecting the number of slave dies in the catheter, up to 7, and another for selecting the number of elements controlled per die, up to 24.

[0101] In the implementation described above, the slave die can control 24 transducer elements. It is also possible to connect fewer transducer elements to the slave die. The number of transducer elements connected in a register daisy chain as shown in Figure 5 is shown in Figure 4. I 2 CThis may be set by parameters within the interface unit 420. The HS unit 440 does not need to know the exact number of transducer elements in the register daisy chain because the register cells are connected in a daisy chain and no data is lost due to shift operations. For example, if a 114-element catheter is required, five slave dies should be used, four of which control 24 elements and one of which controls 18 elements.

[0102] Figure 6 shows a conceptual representation 600 of the transmit Tx register, receive Rx register, and output channel Rxmap register for the circular catheter circumference, slave die 460 boundary, and transducer element 480. Figure 6 shows some exemplary data and their meaning for the three register chains.

[0103] Looking at transducer element 0, as indicated by the arrow, the registers indicate that this element is used to transmit ultrasonic pulses, as indicated by 1 in the transmit Tx register, and used to receive echoes, as indicated by 1 in the receive Rx register, and that the received echoes are transmitted via channel 1, as indicated by 1 in the output channel Rxmap register. A value of 0 in the transmit or receive register indicates that the element is inactive during the transmit or receive period, respectively. A value of 0 in the channel output register indicates that the received echoes should be output on channel 0.

[0104] Note that the transmit Tx register, receive Rx register, and output channel Rxmap register, as well as the combinations of Tx, Rx, and Rxmap bits, may be part of local memory (LM) 130, as shown in Figures 5 and 6 above, and as explained with reference to Figure 2.

[0105] Figure 7 shows a method 700 for controlling an ultrasound imaging catheter having an ultrasound transducer array with multiple ultrasound transducers.

[0106] This method is initiated in step 710 by accessing local memory located at the distal end of the ultrasound imaging catheter.

[0107] In step 720, any one of several activation patterns stored in local memory is selected, and each activation pattern corresponds to some transducer elements to be activated and some transducer elements to be deactivated.

[0108] In step 730, during the imaging phase of the ultrasound imaging catheter, control signals are generated to start or stop multiple transducer elements of the transducer array according to a selected activation pattern, and the imaging phase has a transmission period and a reception period.

[0109] In step 740, the control signal is supplied to the local oscillator.

[0110] In step 750, multiple bits of multiple registers are manipulated to start and / or stop multiple transducer elements of the transducer array according to a selected start pattern, with each bit associated with one of the multiple ultrasonic transducers.

[0111] Modifications of the disclosed embodiments can be understood and implemented by those skilled in the art in carrying out the claimed invention, based on a review of the drawings, disclosures, and appended claims. In the claims, the word “has” does not preclude other elements or steps, and the indefinite article “a” or “an” does not preclude plurality. A single processor or other unit may perform the functions of several items enumerated in the claims. The mere fact that certain means are described in mutually different dependent claims does not imply that combinations of these means cannot be used advantageously. Where a computer program is described above, the computer program may be stored or distributed on a suitable medium, for example, an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, for example, via the Internet or other wired or wireless telecommunications systems. Where the term “adapted to” is used in a claim or specification, the term “adapted to” is equivalent to the term “configured to.” No reference numeral in a claim should be construed as limiting in scope.

Claims

1. In ultrasound imaging catheters, An ultrasonic transducer array provided at the distal end of the ultrasonic imaging catheter and configured to transmit and receive ultrasonic signals, comprising an ultrasonic transducer array having a plurality of ultrasonic transducers, A local memory provided at the distal end of the ultrasound imaging catheter and configured to store multiple activation patterns, wherein each activation pattern corresponds to several transducer elements to be activated and several transducer elements to be deactivated, and the local memory comprises Access the aforementioned local memory, Select any one of the above multiple startup patterns, During the imaging phase of the ultrasound imaging catheter, which has a transmission period and a reception period, a control signal is generated to start or stop the plurality of transducer elements of the transducer array according to the selected activation pattern. A control unit provided at the distal end of the ultrasound imaging catheter, configured as described above, It has, The aforementioned ultrasound imaging catheter Multiple registers, each having multiple bits, and each bit associated with one of the multiple ultrasonic transducers, A local oscillator provided at the distal end of the ultrasound imaging catheter, which communicates with the plurality of registers, receives the control signals generated by the control unit, and generates an oscillation signal including a clock edge for manipulating the plurality of bits in the plurality of registers to start and / or stop the plurality of transducer elements of the transducer array according to the selected start pattern, It further possesses, The local oscillator is configured to operate outside the imaging phase of the ultrasound imaging catheter. Ultrasound imaging catheter.

2. The ultrasound imaging catheter according to claim 1, wherein the local oscillator is configured to operate at a frequency greater than the bandwidth of the plurality of ultrasound transducers.

3. The ultrasound imaging catheter according to any one of claims 1 to 2, wherein the local oscillator is configured to generate a square wave having a given duty cycle, and the given duty cycle is such that the component of the frequency spectrum of the local oscillator is outside the bandwidth of the plurality of ultrasonic transducers.

4. The aforementioned plurality of registers are arranged in a plurality of register groups, and each register group is A first register having a first register bit, A second register having a second register bit, It has, One of the plurality of transducer elements is associated with a first register bit configured to control whether the transducer element is activated or deactivated during the transmission period, and a second register bit configured to control whether the transducer element is activated or deactivated during the reception period. An ultrasound imaging catheter according to any one of claims 1 to 3.

5. The ultrasound imaging catheter according to claim 4, wherein the ultrasound transducer array has a plurality of output channels, each register group further has a third register having a third register bit, and the transducer element is further associated with the third register bit, configured to control which of the plurality of output channels the signal received by the transducer element is output to.

6. The ultrasound imaging catheter according to claim 4 or 5, wherein the plurality of register groups are connected in a daisy chain, and each register group is connected in series with an adjacent register group.

7. The ultrasound imaging catheter according to any one of claims 1 to 6, further comprising a signal adjustment unit provided at the distal end of the ultrasound imaging catheter and configured to apply signal adjustment to the received ultrasound signal.

8. The ultrasonic imaging catheter according to claim 7, wherein the signal adjustment unit has a low-noise amplifier.

9. The ultrasonic imaging catheter according to any one of claims 7 to 8, wherein the signal adjustment unit has one or more time gain compensation units.

10. An ultrasound imaging catheter according to any one of claims 1 to 9, A processing unit configured to communicate with the ultrasound imaging catheter and generate an ultrasound image based on the received ultrasound signal, A display configured to display the aforementioned ultrasound image, An ultrasonic imaging system having the following features.

11. A method for controlling an ultrasound imaging catheter having an ultrasound transducer array having multiple ultrasound transducers, The steps include: accessing a local memory provided at the distal end of the ultrasound imaging catheter; A step of selecting any one of a plurality of activation patterns stored in the local memory, wherein each activation pattern corresponds to a plurality of transducer elements to be activated and a plurality of transducer elements to be deactivated. A step of generating a control signal to start or stop the plurality of transducer elements of the transducer array according to the selected start pattern during the imaging phase of the ultrasound imaging catheter, wherein the imaging phase has a transmission period and a reception period. The steps include supplying the control signal to a local oscillator provided at the distal end of the ultrasound imaging catheter, A step of generating an oscillation signal including a clock edge for manipulating multiple bits of multiple registers to start and / or stop the multiple transducer elements of the transducer array according to the selected start pattern, wherein each bit is associated with one ultrasonic transducer among the multiple ultrasonic transducers. It has, The local oscillator is configured to operate outside the imaging phase of the ultrasound imaging catheter. method.

12. A computer program having computer program code configured to perform the method described in claim 11 when executed on a computer.

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