Ultrasound imaging apparatus

Abstract

An ultrasound imaging device for providing a volumetric ultrasound image of an image volume, where the ultrasound imaging device comprises: a row-column addressed transducer array configured to convert an excitation electrical pulse into an ultrasound pressure field and to convert a received ultrasound echo pressure field into an echo signal; a beamformer module configured to beamform the echo signal using dynamic receive focus to produce corresponding image values at a first set of image points within the image volume; and a reconstruction module configured to determine a set of trajectories, each trajectory intersecting an image point of the first set of image points, map a second set of image points of the image volume onto the first set of image points, and calculate a corresponding image value at the mapped image point of the second set of image points based on an image value of the image point of the first set of image points.

Description

Technical Field

[0001] The following relates generally to ultrasound, and more particularly to ultrasound imaging devices, corresponding methods, data processing systems, and computer programs. Background Art

[0002] High frame rate 3-D imaging with broad volume coverage can be achieved by using 2-D probes in combination with synthetic aperture imaging. However, for most 2-D probe designs, the number of channels increases quadratically with the number of elements in the aperture side length. In practice, this makes it very difficult, if not impossible, to achieve low F-numbers at large imaging depths from a manufacturing and processing perspective. Furthermore, even a small number of elements in the aperture side length results in a channel count that far exceeds that of a typical 2-D imaging device.

[0003] Row-column addressed arrays (RCA) provide a solution to high channel counts by addressing the elements in a 2-D array by row and column, and this reduces the total number of channels to increase linearly with the number of elements in the side length of the aperture rather than quadratically.

[0004] US 10,705,210 discloses an ultrasonic imaging device that uses a synthetic aperture sequential beamforming technique for three-dimensional imaging, the device having a row-column addressed transducer array. This prior art method uses fixed focusing to simplify the propagation path of the sound wave.

[0005] Another approach to row-column imaging is to use dynamic receive focusing, which can more accurately model the propagation of sound waves and is currently used by most ultrasound scanners for imaging.

[0006] Row-column imaging with dynamic receive focusing is described in MF Rasmussen, TL Christiansen, EV Thomsen, and JA Jensen, “3-D imaging using row–column-addressed arrays within integrated apodization—Part I: Apodization design and line element beamforming,” IEEE Trans. Ultrason., Ferroelec., Freq. Contr. (IEEE Journal of Ultrasonics, Ferroelectrics, and Frequency Control), vol. 62, no. 5, pp. 947–958, 2015.

[0007] et al., “Tensor Velocity Imaging With Motion Correction,” IEEE Transactions on ultrasonics, ferroelectrics, and frequency control, Vol. 62, No. 5, May 2021, presents a motion compensation procedure for improving the accuracy of tensor velocity estimates for synthetic apertures of row and column arrays.

[0008] Although it has been found that row-column imaging with dynamic receive focusing provides high image quality, this approach places high demands on the processing unit. This problem is particularly severe when acquiring volumetric images, since these images typically contain a large number of image points. In particular, the high processing requirements severely limit the pulse repetition frequency for real-time imaging. However, many clinical applications, such as real-time streaming applications, require high pulse repetition rates.

[0009] It would therefore remain desirable to provide an imaging apparatus that facilitates high pulse repetition frequencies, such as for real-time volumetric beamforming, while providing high image quality.

[0010] In view of at least the foregoing, a need remains unaddressed for improved methods of row-by-row ultrasound imaging. Summary of the invention

[0011] Various aspects disclosed herein are intended to solve the above-mentioned problems and / or other problems, or at least provide a method that can replace the existing methods.

[0012] According to one aspect, an ultrasound imaging apparatus is disclosed for providing a volumetric ultrasound image of an image volume. The term "volume ultrasound image" means a 3-D ultrasound image, which may be represented as a 3-D raster of image points, for example, each image point having an image value associated therewith.

[0013] Embodiments of ultrasound imaging devices include:

[0014] a) row-column addressed transducer array,

[0015] b) a beamformer module, and

[0016] c) Reconstruction module.

[0017] The row-column addressed transducer array is configured to convert the excitation electrical pulses into an ultrasound pressure field and convert the received ultrasound echo pressure field into an echo signal. The beamformer module is configured to beamform the echo signal using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume.

[0018] The reconstruction module is configured as:

[0019] - determining a set of trajectories, each trajectory intersecting an image point of the first set of image points; each determined trajectory may be defined according to a virtual transmitter position, in particular by a position along which a time of flight from the virtual transmitter position to a closest position on the apertures of the receiving transducer elements of the first transducer array and the second transducer array is constant,

[0020] - mapping a second set of image points of the image volume onto the first set of image points, and

[0021] - calculating corresponding image values ​​at mapped image points of the second set of image points from the image values ​​of the image points of the first set of image points, thereby obtaining a volumetric ultrasound image of the image volume.

[0022] The ultrasound imaging device may be configured to control a row-column addressed transducer array to perform a plurality of ultrasound transmissions corresponding to ultrasound transmitted from corresponding virtual transmitter positions; wherein the beamformer module and the reconstruction module are configured to calculate a plurality of low-resolution volume images, each low-resolution volume image corresponding to a corresponding virtual transmitter position, and wherein the imaging device further comprises an image combiner module configured to combine the plurality of low-resolution volume images corresponding to different virtual transmitter positions into a combined high-resolution volume image, the combined high-resolution volume image having a higher spatial resolution than the low-resolution volume image.

[0023] Embodiments of the ultrasound imaging apparatus disclosed herein are capable of providing volumetric images that are no different from the prior art row-column imaging method with dynamic receive focusing, but with significantly fewer operations.

[0024] In prior art row-column imaging using dynamic receive focusing, the number of processing operations is proportional to the number of array elements multiplied by the number of image points. In embodiments of the methods used in the various aspects disclosed herein, the number of operations is proportional only to the number of image points. The inventors have realized that this reduction can be achieved because at certain locations in the volume, the flight time of the sound measured to the closest position of the hole is constant. Therefore, the image values ​​along these locations will also be approximately constant. This means that the imaging device only needs to calculate the image value of one of the locations to obtain the image values ​​of all the remaining locations. Various embodiments disclosed herein take advantage of this implementation in 3-D imaging, thereby greatly reducing the number of processing operations, thereby facilitating real-time image acquisition at higher pulse frequencies. Real-time image acquisition at high pulse frequencies in turn promotes various applications, such as clinical applications. Such applications include, but are not limited to, anatomical imaging, super-resolution imaging, contrast imaging, and velocity imaging, such as tensor velocity imaging.

[0025] The row-column addressed transducer array comprises a plurality of transducer elements. The transducer elements may be configured to convert an excitation electrical pulse into an ultrasonic pressure field and to convert a received ultrasonic pressure field (echo) into an electronic (e.g., radio frequency (RF)) echo signal. The echo and thus the echo signal are generated in response to the interaction of the transmitted pressure field with a substance (e.g., tissue, etc.). Therefore, the ultrasonic imaging device may include a transmit circuit configured to generate an excitation electrical pulse, in particular to cause the row-column addressed transducer array to transmit a transmit sequence of ultrasonic pressure fields corresponding to corresponding virtual transmitter positions.

[0026] The row-column transducer array may include a first group of transducer elements, which define a first transducer array, in particular a first 1-D transducer array, along a first axis. Each transducer of the first transducer array may extend along a first longitudinal axis, which may be orthogonal to the first axis. To this end, the transducers of the first transducer array may form rows or columns of a 2-D array of transducer elements, wherein a single channel may be used to address the transducer elements of each row or column. Therefore, each column or row may be addressed as a single elongated transducer of the 1-D transducer array. The row-column transducer array may include a second group of transducer elements, which define a second transducer array, in particular a second 1-D transducer array, along a second axis. Each transducer of the second transducer array may extend at a second longitudinal axis, which may be orthogonal to the second axis. To this end, the transducers of the second transducer array may form columns or rows of a 2-D array of transducer elements, wherein a single channel may be used to address the transducer elements of each column or row. The first axis may be orthogonal to the second axis.In particular, the row-column addressed array may define two elongated 1-D transducer arrays, one array consisting of row elements and the other array consisting of column elements of a 2-D array of transducer elements.

[0027] In some embodiments, the ultrasound imaging device is configured to transmit ultrasound waves through a first transducer array and receive backscattered ultrasound waves, ie, echoes, through a second transducer array.

[0028] The reconstruction module determines a trajectory in the image volume. This determination may involve determining a trajectory along which image values ​​are constant or at least approximately constant. To this end, the reconstruction module may determine the trajectory as a set of positions within the image volume, wherein the flight time from the virtual transmitter position via any one of the set of positions along the trajectory to the closest position on the aperture of the receiving transducer element of the first transducer array and the second transducer array is constant along the trajectory, i.e., the same for all positions in the set of positions. Therefore, the set of trajectories is a flight time trajectory that is constant relative to the virtual transmitter position. The determination of the trajectory depends on the virtual transmitter position. Therefore, the determination may be made for a set of virtual transmitter positions, thereby obtaining a set of trajectories, each trajectory in the set of trajectories corresponding to a different virtual transmitter position. The representation of the generated trajectory, and / or the representation of the corresponding mapping of the image coordinates of the second set of image points along a corresponding one of the determined trajectories to the first set of image points can be stored in a memory and reused to create a subsequent volume ultrasound image using the same virtual transmitter position. To this end, in some embodiments, the reconstruction module is configured to map each image coordinate of the image volume onto the first set of image points and store the representation of the mapped image coordinates. Thus, the reconstruction module may be configured to compute a plurality of volumetric images using the stored representations of the mapped image coordinates.

[0029] The volume ultrasound image obtained by RCA based on the echo signal corresponding to a single virtual transmitter position provides limited spatial resolution, especially along the extension direction of the receiving transducer element. In order to improve the spatial resolution, the ultrasound imaging device can be configured to control the row and column addressing transducer array to perform a transmission sequence including multiple ultrasound transmissions corresponding to the ultrasound transmitted from the corresponding virtual transmitter position. The virtual transmitter position can be distributed in the extension direction of the single receiving transducer element and / or distributed at different distances from the array. Therefore, the beamformer module and the reconstruction module can be configured to calculate a plurality of low-resolution volume images (LRV), each low-resolution volume image corresponding to a corresponding virtual transmitter position. The imaging device can further include an image combiner module, which is configured to combine a plurality of low-resolution volume images corresponding to different virtual transmitter positions into a combined high-resolution volume image (HRV), the combined high-resolution volume image having a spatial resolution higher than the corresponding resolution of the low-resolution volume image at least in one spatial direction. The combination may include calculating the image value of the high-resolution volume image as the sum or weighted sum of the image values ​​of the same image point of the corresponding low-resolution volume image.

[0030] Therefore, various embodiments of the method disclosed herein can perform dynamic receive focusing along all three spatial axes. In particular, dynamic receive focusing can be performed along the elongation direction of the receive transducer element (i.e., the second elongation axis) by combining low-resolution volume images acquired for different virtual transmitter positions.

[0031] To this end, the beamformer module may be configured to beamform echo signals provided by the transducer array in response to ultrasound echoes received by the row-column addressed sensor array in response to transmitting to generate a corresponding plurality of two-dimensional images, each two-dimensional image corresponding to one of the virtual transmitter positions. The reconstruction module may then be configured to calculate at least a first low-resolution volumetric image of the plurality of low-resolution volumetric images, the first low-resolution image corresponding to the first virtual transmitter position. To this end, the reconstruction module may be configured to perform interpolation. The reconstruction module may calculate at least the first low-resolution volumetric image by at least:

[0032] - determining a first set of trajectories associated with a first virtual transmitter position,

[0033] - mapping image coordinates of the image volume to image locations of the first two-dimensional image using the first set of trajectories, and

[0034] - interpolating image values ​​at the mapped image coordinates from image values ​​of the first two-dimensional image plane, the interpolated image values ​​at the mapped image coordinates representing the first low-resolution volumetric image.

[0035] The beamformer module can be configured to perform delay and sum beamforming to calculate image values ​​for the first set of image points. Beamforming the echo signals using dynamic receive focusing typically includes applying corresponding delays to the responses of each receive transducer element originating from the image point and coherently adding these delayed responses. The delay is derived from the round-trip flight time (TOF), which is the propagation time of the transmitted wave from the transmitting source (i.e., the virtual source position) to the image point and then back to a transducer element of the receive transducer array. Therefore, beamforming can include calculating the flight time for each virtual transmitter position and each image point of the first set of image points. In particular, a new set of delay values ​​is therefore calculated for each image point. Thus, beamforming the echo signals using dynamic receive focusing includes calculating the flight time along the shortest path from the virtual transmitter position to the image point, and further from the image point to the receive transducer element or receive aperture of the row-column addressed transducer array, as described, for example, in MF Rasmussen, TL Christiansen, EV Thomsen, and JA Jensen, “3-D imaging using row–column-addressed arrays with integrated apodization—Part I: Apodization design and line element apodization”. beamforming (3-D imaging using row-column addressed arrays with integrated apodization - Part I: Apodization design and line element beamforming)", IEEE Trans. Ultrason., Ferroelec., Freq. Contr. (IEEE Journal of Ultrasonics, Ferroelectrics and Frequency Control), Vol. 62, No. 5, pp. 947-958, 2015, the flight time associated with a virtual transmitter position and an image point can be calculated based on the path length of the shortest path extending from the virtual transmitter position to the image point and from the image point to a receiving transducer element of a second transducer array (particularly along the elongated receiving transducer element extending to the position closest to the image point).

[0036] The first set of image points may define a two-dimensional image surface, preferably an image plane, in the image volume, i.e. all image points of the first set of image points may be located on the two-dimensional image surface. Thus, the image values ​​of the image points of the first set of image points may represent a two-dimensional image. The two-dimensional image may be regarded as a 2-D projection of the image volume on the two-dimensional image surface, the projection being defined by the trajectory. The two-dimensional image surface may be selected such that all image points in the image volume may be mapped, in particular projected, onto the two-dimensional image surface via a set of trajectories. The second set of image points comprises image points displaced from the two-dimensional image surface. It is to be understood that the second set of image positions may further comprise the first set of image points and may therefore be considered to be mapped onto the first set of image points. Thus, the image values ​​at the second set of image points represent a volumetric ultrasound image of the image volume.

[0037] The image plane may extend orthogonally to the longitudinal direction of the receiving transducer elements. The image plane may extend from a plane defined by the transducer array, in particular orthogonally thereto. In one embodiment, the position of the image plane along the longitudinal direction of the receiving transducer elements corresponds to, in particular is equal to, the position of the virtual transmitter position along said longitudinal direction of the receiving transducer elements.

[0038] The beamformer module can be configured to calculate image values ​​at image points distributed on a two-dimensional image surface (particularly an image plane) at a suitable (e.g., predetermined) sampling rate or raster density. The sampling rate can be uniform or can vary across the image plane, for example, the sampling rate in one direction is greater than the sampling rate in another direction. In some embodiments, the ultrasound imaging device is configured to sample the beamformed image plane at least at the Nyquist frequency along at least a direction extending from a plane defined by the transducer array, thereby facilitating accurate interpolation by the reconstruction module.

[0039] The device may include one or more processing units that are programmed or otherwise configured to implement a beamformer module and / or a reconstruction module and / or a combiner module. The one or more processing units may include a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, etc. The beamformer module and the reconstruction module may be implemented by the same processing unit or by different processing units.

[0040] In some embodiments, the imaging device includes a probe and a console operably coupled to the probe. The probe includes a row-column addressed transducer array, and the console may include a processing unit implementing a beamformer module and / or a reconstruction module and / or a combination module. In some embodiments, some signal processing, such as some beamforming operations or all, may be performed by a processing unit included in the probe.

[0041] In some embodiments, the imaging device includes a transmitting circuit and a receiving circuit, wherein the transmitting circuit is configured to generate an excitation electrical pulse to excite the transducer element, and the receiving circuit is configured to receive the electrical signal (e.g., RF signal) generated by the transducer element and optionally condition and / or pre-process it. The transmitting and / or receiving circuits may be included in the console.

[0042] In some embodiments, the processing unit is configured to implement a processing pipeline that processes received electrical signals, in particular received RF signals, to create a representation of one or more volumetric ultrasound images.

[0043] The same and / or a separate processing unit may be configured to perform additional processing on one or more volumetric ultrasound images, such as for velocity imaging and / or another type of 3-D ultrasound imaging.

[0044] It will be appreciated that the generation of one or more ultrasound images and optional further processing from the received electrical signals can be implemented by a single processing unit. Alternatively, different operations can also be assigned to multiple processing units. In some embodiments, the processing unit that implements the signal and / or image processing is included in the console. In some embodiments, at least a portion of the signal processing and / or subsequent image processing can be performed by a computing device separate from the console. With this embodiment, the RF signal stored in the memory and / or the beamforming image stored in the memory of the computing device or the image received from the console (e.g., via an appropriate wired or wireless connection) can be loaded and processed by the image processing pipeline to generate the resulting 3-D image.

[0045] The imaging device may further include a display, and the display is configured to display the representation of the generated volumetric image. The display may be included in the console or in a separate computing device.

[0046] In another aspect, a method, particularly a computer-implemented method, comprises:

[0047] - receiving an echo signal from the row-column addressed transducer array, the echo signal representing an ultrasound echo pressure field received by the row-column addressed transducer array in response to transmitting the ultrasound pressure field,

[0048] - beamforming the received echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume,

[0049] - determining a set of trajectories, each trajectory intersecting an image point in the first set of image points,

[0050] - mapping a second set of image points of the image volume onto the first set of image points, and

[0051] - calculating corresponding image values ​​at mapped image points of the second set of image points from the image values ​​of the image points of the first set of image points, thereby obtaining a volumetric ultrasound image of the image volume.

[0052] In yet another aspect, a computer program includes instructions that, when executed by a computer or other data processing system, cause the computer or other data processing system to perform the computer-implemented operations of the method described herein. The computer program may be a computer-readable storage medium storing the instructions or a data signal encoding the instructions.

[0053] According to another aspect, embodiments of a data processing system are disclosed herein, the system being configured to perform the operations of the methods described herein. In particular, the data processing system may store program code that, when executed by the data processing system, causes the data processing system to perform the steps of the methods described herein. The data processing system may be embodied as a single computer, or a distributed system including multiple computers, such as a client-server system, a cloud-based system, etc.

[0054] Those skilled in the art will recognize other aspects of the present application upon reading and understanding the accompanying description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The various aspects disclosed herein will be illustrated by way of example and not limitation thereof, in the accompanying drawings, in which like reference numerals indicate similar elements:

[0056] Figure 1 An example of an imaging device according to an embodiment of this document is schematically shown.

[0057] Figure 2 Schematically illustrated is a row-column addressed transducer array according to embodiments disclosed herein.

[0058] Figure 3A and Figure 3B Schematically illustrates a coordinate system defined relative to a row-column addressed transducer array according to embodiments disclosed herein.

[0059] Figure 4 Schematically illustrates an embodiment according to the present invention Figure 1 An example processing pipeline for an imaging device.

[0060] Figure 5A-Figure 5C Schematically illustrates an example of a time-of-flight path used in RCA delay-and-sum beamforming according to embodiments disclosed herein.

[0061] Figure 6 The schematic diagram shows how elements along the y' axis can be efficiently synthesized according to embodiments disclosed herein.

[0062] Figure 7An example method according to embodiments herein is shown.

[0063] Figure 8A-8C Examples of low-resolution volumetric images and combined high-resolution volumetric images are shown.

[0064] Figure 9A-9B Shown is an output comparison between a conventional DAS RCA beamformer and an embodiment of the imaging apparatus and method disclosed herein.

[0065] Figure 10A-10B 1 shows beamforming using a conventional DAS RCA beamformer and embodiments of the imaging apparatus and method disclosed herein. Figure 9A-9B 3-D rendering of a cyst model.

[0066] Fig.11 A comparison of computation time as a function of the number of samples and channels in the receiving well is shown. DETAILED DESCRIPTION

[0067] An ultrasound imaging apparatus and related method for providing a volumetric ultrasound image of an image volume and a corresponding method for alleviating one or more of the above-mentioned disadvantages of prior art volumetric imaging methods are described below. In general, the ultrasound imaging apparatus comprises:

[0068] a) a row-column addressed transducer array configured to convert an excitation electrical pulse into an ultrasonic pressure field, and to convert a received ultrasonic echo pressure field into an echo signal,

[0069] b) a beamformer module configured to beamform the echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume, in particular at image points on an image plane within the image volume;

[0070] c) The reconstruction module is configured as follows:

[0071] - determining a set of trajectories, each trajectory intersecting an image point in the first set of image points,

[0072] - mapping a second set of image points of the image volume onto the first set of image points, in particular onto image points outside the image plane, and

[0073] - calculating corresponding image values ​​at mapped image points of the second set of image points from the image values ​​of the image points of the first set of image points, thereby obtaining a volumetric ultrasound image of the image volume.

[0074] Figure 1An example imaging device 102 is shown, which is configured to perform volumetric ultrasound imaging of an object. The imaging device 102 includes a probe 104 and a console 106, which are interconnected by suitable complementary hardware (electromechanical connectors 108 and 110 and cable 112, etc. as shown) and / or a wireless interface (not visible).

[0075] The probe 104 includes a row-column addressed transducer array (RCA) 114 having a plurality of transducer elements 116. The transducer array 114 includes a planar array, a curved array or other shaped array, a fully filled array or a sparse array, etc. The transducer elements 116 are configured to convert the excitation electrical pulses into an ultrasonic pressure field and convert the received ultrasonic pressure field (echo) into an electronic (e.g., radio frequency (RF)) echo signal. Therefore, the echo signal is generated when the transmitted pressure field interacts with a substance (e.g., human tissue, other biological or non-biological materials, etc.). The transducer elements of the RCA are arranged in a 2-D array.

[0076] The console 106 includes a transmit circuit (TX) 118 and a receive circuit (RX) 120, wherein the transmit circuit is configured to generate excitation electrical pulses that excite the transducer elements 116 and the receive circuit is configured to receive the RF signals generated by the transducer elements 116. In one embodiment, the RX 120 (or other circuits) are also configured to condition or pre-process the RF signals, such as amplification, digitization, etc. In the illustrated embodiment, a TX / RX controller 122 is configured to control the TX 118 and the RX 120 to perform the transmit and receive operations of the RCA. The TX 118 and the RX 120 address the transducer elements of the RCA by row and column, respectively. To do this, the signals received along the rows or columns are summed to produce one signal per row or column. Therefore, the RCA 114 effectively forms two orthogonal 1-D arrays having elongated transducer elements, such as Figure 2 described.

[0077] In one embodiment, TX 118 and RX 120 are controlled to cause RCA to perform volumetric imaging by transmitting from one of the 1-D arrays and receiving backscattered signals from the other 1-D array or the same 1-D array. For example, a subset (i.e., one or a subset) of the transmit array elements may be excited to simultaneously generate a pressure field, collectively emitting a focused beam corresponding to the emission of a virtual emitter position (particularly a virtual line emitter). All or a subset of the elements of the receive array may be used to receive echoes. This may be repeated for multiple different subsets of the transmit array, particularly for different positions of the virtual emitters, wherein each transmit / receive provides data to generate a low-resolution volumetric image, and a high-resolution volumetric image may be generated by combining multiple low-resolution images corresponding to different virtual emitter positions as described herein. Examples of suitable sequences are described in Jensen et al., "Synthetic aperture ultrasonic imaging," Ultrasonics, vol. 44, pp. 59-64, e5–e15, 2006. Another example of using plane waves is mentioned in Tanter et al., "Ultrafast imaging in biomedical ultrasound", IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2014, 61, 1, pp. 102-119.

[0078] The console 106 also includes a processing unit 124. The processing unit 124 may include one or more processors (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, etc.) configured to execute computer-readable instructions encoded or embedded on a computer-readable storage medium such as a memory 126 to perform computer-implemented operations described herein. In general, the processing unit 124 is configured to process RF signals to create a set of low-resolution volumetric ultrasound images and combine the low-resolution volumetric ultrasound images to generate a high-resolution volumetric ultrasound image. In particular, the processing unit 124 is configured to implement a processing pipeline including a beamformer module, a reconstruction module, and a combiner module as described herein.

[0079] As described in more detail below, in one example, the processing unit 124 implements a beamformer module, a reconstruction module, and a combiner module. The beamformer module beamforms the received echo signals to generate beamformed low-resolution image planes corresponding to different virtual transmitter positions. The reconstruction module calculates a low-resolution volumetric image based on each beamformed low-resolution image plane. To this end, the reconstruction module determines a trajectory of at least approximately constant image values ​​for each low-resolution image, the trajectory intersects the beamformed low-resolution image plane, maps the image coordinates of the image volume onto the beamformed low-resolution image plane using the determined trajectory, and interpolates the image values ​​at the mapped image coordinates based on the image values ​​of the beamformed low-resolution image plane, thereby obtaining a low-resolution volumetric ultrasound image. The combiner module combines the resulting multiple low-resolution volumetric ultrasound images corresponding to different virtual transmitter positions into a combined high-resolution volumetric ultrasound image.

[0080] The console 106 may also include a scan converter 128 and a display 130. The scan converter 128 is configured to scan convert each image for display, for example, by converting the image to a coordinate system of the display 130. A representation of the high-resolution volumetric ultrasound image is then displayed, such as a 3D rendering, a cross-section, or other type of representation. In addition to displaying the generated representation of the high-resolution volumetric ultrasound image, the high-resolution volumetric ultrasound image may also be stored and / or further processed, for example, to identify and / or classify structures or features of the imaged object.

[0081] The console 106 also includes a user interface 132, which includes one or more input devices (e.g., buttons, a touch pad, a touch screen, etc.) and one or more output devices (e.g., a display, a speaker, etc.). The console 106 also includes a controller 134, which is configured to control one or more of the transmit circuit 118, the receive circuit 120, the TX / RX controller 122, the processing pipeline 124, the scan converter 128, the display 130 and / or the user interface 132.

[0082] It is understood that other embodiments of the imaging device may include alternative or additional components, and / or the arrangement of the components may be different, and / or some components may be omitted. For example, the distribution of components between the probe and the console may be different, or the device may include an additional remote data processing system.

[0083] Figure 2 Schematically illustrates a row-column addressed transducer array according to an embodiment disclosed herein. In particular, Figure 2An example 6×6 RCA array 202 (N=6) is schematically shown. Each column 204 includes a conductive trace 206 in electrical communication with each element 208 of the column 204, wherein an electrode 210 is in electrical communication with the conductive trace 206. Each row 212 includes a conductive trace 214 in electrical communication with the elements 208 of the row 212, wherein an electrode 216 is in electrical communication with the conductive trace 214. The RCA effectively converts the 36-element 6×6 2-D array 202 into a 6-element 1-D column array 218 and an orthogonal 6-element 1-D row array 220. This effectively reduces the number of element channels from N to 1. 2 Reduced to 2N.

[0084] Suitable RCA arrays are described in US 10,302,752 and US 10,806,432.

[0085] In addition, the transducing element 208 may also include integrated apodization, which may be the same or different for each element. An example is described in WO2015 / 092458. In addition, the 2-D array 202 may have a planar 1-D array, one curved 1-D array, two curved 1-D arrays, a single curved lens in front of or behind one of the 1-D arrays, a double curved lens in front of or behind the 1-D array, a combination of at least one curved 1-D array and at least one curved lens, etc. An example is described in WO 2017 / 212313.

[0086] exist Figure 2 In the embodiment of the present invention, each row and each column has its own front-end circuit. For example, electrode 210 is in electrical communication with its own front-end circuit (not visible), and electrode 216 is in electrical communication with its own front-end circuit (not visible). In a variant, pairs of rows and columns can share front-end circuits, as described in U.S. Patent 10,806,432. In the case of shared front-end circuits, electrodes 210 and 216 are both in electrical communication with the same switch (not visible), which switches between electrodes 210 and 216 for transmission and reception. The switch can be part of the shared front-end circuit and / or separate from it. This configuration further reduces the number of channels from 2N to N.

[0087] Figure 3A and Figure 3BA coordinate system defined relative to a row-column addressed transducer array according to an embodiment disclosed herein is schematically shown. It will be appreciated that the rows of the RCA can be used to equalize the volume to be imaged and the columns can be used to receive backscattered signals, and vice versa, i.e., the columns of the RCA can be used to equalize the volume to be imaged and the rows can be used to receive backscattered signals. Therefore, for ease of explanation, it is convenient to introduce a coordinate system relative to the receiving aperture. Of course, other coordinate systems may also be used. For the purposes of this specification, the coordinate system is defined such that x' represents the axis of arrangement of the elements of the receiving array and y' represents the direction of elongation of each receiving element.

[0088] Please note that if Figure 2 The (x,y) coordinate system is defined as shown, that is, the rows of the array extend along the x-axis and the columns extend along the y-axis, then Figure 3A-3B As shown, if the row holes receive, then (x'; y') = (y; x), and if the column holes receive, then (x'; y') = (x; y). In particular, Figure 3A shows the (x', y') coordinate system when the row hole is received, and Figure 3B The (x', y') coordinate system is shown when the array holes are received. In any case, the z direction is the direction extending orthogonally out of the plane of the array, ie, orthogonal to the (x', y') plane, and the origin of the coordinate system is defined at the center of the array.

[0089] Figure 4 A non-limiting example of a processing pipeline, generally designated 400, is schematically shown, implemented by an embodiment of an imaging device disclosed herein, such as by Figure 1 The processing pipeline 400 shown receives RF signals from the receiving circuit 120 as input and outputs one or more volumetric ultrasound images.

[0090] The illustrated processing pipeline 400 includes a beamformer module 410. The beamformer module 410 is configured to beamform the RF signal onto an image plane and output a series of 2-D images, each image being associated with a corresponding virtual transmitter position. Non-limiting examples of suitable beamforming are described in MF Rasmussen, TL Christiansen, EV Thomsen, and JA Jensen, "3-D imaging using row–column-addressed arrays within integrated apodization—Part I: Apodization design and line element beamforming," IEEE Trans. Ultrason., Ferroelec., Freq. Contr. (IEEE Journal of Ultrasonics, Ferroelectrics, and Frequency Control), Vol. 62, No. 5, pp. 947–958, 2015. Another non-limiting example is described in Stuart et al., “Real-time volumetric synthetic aperture software beamforming of row-column probe data,” IEEE Trans. Ultrason., Ferroelec., Freq. Contr. (IEEE Journal of Ultrasonics, Ferroelectrics, and Frequency Control), April 8, 2021. Other beamforming methods are also considered herein.

[0091] To this end, the transducer array is controlled to generate an ultrasound transmission corresponding to the transmission of the virtual transmitter located at the virtual transmitter position. For each transmission, some or all elements of the transmission array are controlled to transmit ultrasound signals with appropriate phase offsets, thereby generating an ultrasound front that appears to originate from the virtual transmitter position. The RCA is controlled to generate a series of transmission signals corresponding to different positions of the virtual transmitter, in particular different positions along the y' and / or z direction. For each transmission, the elements of the receiving array receive the backscattered signals from the same volume, and for each transmission, the beamformer module creates a corresponding 2-D image associated with the transmission (i.e., for each virtual transmitter position). To this end, the beamformer defines an image plane, which can be the same or different for each transmission. The image plane can be defined as parallel to the (x',z) plane at an appropriate position along the y' axis, for example at the y' position of the corresponding virtual transmitter. For each image point on the image plane, the beamformer module performs a beamforming calculation to calculate the image value at the image point. The image points can be distributed on the image plane as an appropriate raster. The spatial density or sampling rate of the image points can be the same or different along the x' and z directions. The beamforming process involves a time-of-flight calculation for each virtual transmitter position and each image point. Using dynamic receive focusing, the beamforming process takes into account the flight time from the virtual transmitter position to the image point and back (specifically directly back by the shortest path) to the receiving element, e.g. Figure 5A-Figure 5C shown.

[0092] Figure 5A-Figure 5C Schematically illustrates an example of a time-of-flight path used in RCA delay-and-sum beamforming according to an embodiment disclosed herein. In particular, Figure 5A-Figure 5C The positions of the receive transducer elements 521 , the image points 530 , and the virtual transmitter 510 of the receive array 520 as seen from different directions are shown. Figure 5A shows a 3-D view, Figure 5B shows a side view along the y' direction, Figure 5C A top view along the z-direction is shown.

[0093] Since the elements of the transmit array are elongated in the x' direction, the virtual source 510 is a line extending in the x' direction, such as Figure 5A-Figure 5C shown.

[0094] In the (x', y', z) coordinate system, the position of the virtual transmitter 510 will be represented as (x', y', z). v ,z v ), the position of the image point 530 will be expressed as From the virtual transmitter 510 via the image point to (x e ,y′,0) is represented by a dashed line 540 .

[0095] Therefore, the total path from the reference point on the array to the virtual transmitter, from the virtual transmitter to the image point, and then from the image point back to the receiving element can be expressed as

[0096]

[0097] in:

[0098]

[0099] Therefore, the time of flight (ToF) used by the beamformer module for RCA delay and sum (DAS) beamforming is given by is given by , where c is the speed of sound in the imaged medium.

[0100] Figure 5B The ToF path diagram in also shows that focusing in the zx' plane is similar to 2-D plane wave imaging, for example, see G. Montaldo, M. Tanter, J. Bercoff, N. Benech and M. Fink, "Coherent plane-wave compounding for very high frame rate ultrasonography and transient elastography," IEEE Trans. Ultrason., Ferroelec., Freq. Contr. (IEEE Journal of Ultrasound, Ferroelectrics and Frequency Control), Vol. 56, pp. 489-506, March 2009. Therefore, it can be understood that in the various embodiments described herein, dynamic receive focusing is achieved in the x and z' dimensions. In fact, dynamic receive focusing can also be achieved along the y' axis, although there is only one receiving element along this direction. In order to achieve dynamic receive focusing along the y' axis, the various embodiments disclosed herein combine images acquired from different virtual transmitting sources located at different positions in the zy' plane. As Figure 6 As shown, the RCA is able to change the virtual source position in the y'z plane by using differently oriented apertures in transmit and receive, and the RCA is able to resolve upward looking objects because it can change the virtual source position in that direction.

[0101] Figure 6 FIG. 1 is a diagram illustrating how elements along the y′ axis can be efficiently synthesized in accordance with various embodiments disclosed herein. Figure 6Two rows of figures are included. The top row of figures shows the ToF path 540 for a fixed image point 530 and a fixed receiving element 521, but the position of the virtual transmitter 510 is different. The bottom row of figures shows that the transmissions from different virtual transmitter positions correspond to the transmissions from the fixed virtual transmitter position 510, but the receiving element 521 is moved along the y' axis. This shows that moving the transmission source along the y' axis is actually equivalent to receiving the transmission source from different elements along the y' axis. Combined, the different transmissions synthesize a larger receiving aperture, thereby providing focusing along the y' axis. Therefore, this method can be called "synthetic aperture" (SA) imaging.

[0102] Figure 8A-8C Focusing along the y' axis is further demonstrated, illustrating how the volumetric image data acquired at different virtual transmitter positions can be combined to form a high-resolution volumetric ultrasound image. Figure 8A-8C Simulated volumetric image data of a point target located at the center of the image volume (in this case (0; 0; 20) mm) is shown. Figure 8A-8C Demonstrates how point targets are resolved from an RCA firing sequence consisting of 22 unique virtual transmitter positions. Figure 8A-8C The RF data for the beamforming images shown were all acquired using a 3MHz 64+64RCA in a Field II simulation environment (see, for example, “Field: A program for simulating ultrasound systems,” Med.Biol.Eng.Comp., vol. 10th Nordic-Baltic Conference on Biomedical Imaging, vol. 4, Supplement 1, Part 1, pp. 351-353, 1996 and JA Jensen and NBSvendsen, “Calculation of pressure fields from arbitrarilyshaped, apodized, and excited ultrasound transducers,” IEEE Trans. Ultrason., Ferroelec., Freq. Contr., vol. 39, No. 2, pp. 262-267, 1992).

[0103] Fig. 8A and Figure 8BThe beamformed volumetric image data from two transmits with corresponding virtual transmitter positions are shown. The individual volumetric images from the individual transmitter positions are also referred to as low resolution volumetric images (LRVs) because they are not able to individually visualize a point target placed at the center of the volume resolved in all three dimensions. They resolve the point target as a line rather than a point. Only by combining different LRVs can point targets be accurately represented in all three dimensions, as shown in FIG. Figure 8C As shown in FIG. 1 , the figure shows a volume image obtained by combining 22 LRVs obtained using corresponding virtual transmitter positions. Figure 8C In , the imaged point scatterers are resolved at the intersections of the LRV lines. Therefore, the combined image can spatially resolve point objects in all three dimensions and is therefore also called a high-resolution volumetric image (HRV).

[0104] The inventors have realised that the creation of LRVs can be performed efficiently, since the beamforming operation to create each LRV does not need to be performed for every image point in the volume to be imaged. The beamforming operation need only be performed for a set of representative image points, in particular image points in an image plane. The remaining image values, in particular image values ​​outside the image plane, can then be calculated from the image values ​​of the set of representative image points, in particular image values ​​in the image plane.

[0105] For example, Figure 8A-8C It is shown that LRV alone can only determine the y' position of the point target, and the visualization amplitude is constant along the trajectory in the y'z plane. The trajectory depends on the virtual launcher position, i.e., the trajectory is Fig. 8A and Figure 8B The LRVs shown are different. The trajectories from the two LRVs intersect at the point target, and the point target can be resolved because the LRVs combine coherently at this location. The LRVs can be considered as a "back projection" of the projection of the point target on the x'z plane, and the volume is resolved by projecting the volume from different angles. However, instead of acquiring each image point in the LRV independently, various embodiments described herein determine back-projected trajectories and use them to acquire the remaining image points in the volume from image points in a single x'z plane.

[0106] Therefore, refer again Figure 4 , the processing pipeline 400 includes a reconstruction module 420. For each 2-D image generated by the beamformer module 410, the reconstruction module determines a set of back-projected trajectories.

[0107] For a given 2-D image, that is, for a given virtual emitter position, its back-projection trajectory can be obtained by solving the trajectory, where the distance That is, the virtual transmitter position to the image point Then return to the closest position x on the receiving holep The shortest distance between the two is constant. This solution corresponds to or at least approximates the solution obtained by dynamic apodization, i.e., the width of the receiving hole depends on the depth z of the image point relative to the receiving hole. p .

[0108] This trajectory yields locations in the image volume where the ToF to the closest location on the aperture is constant. If dynamic receive apodization is used, this trajectory also corresponds to locations where the entire ToF curve is constant relative to the effective part of the aperture; otherwise, it is still a good approximation. Assume that z p ≥0 and (y p ,z p )≠(y v ,z v ), the trajectory can be expressed as (x'; y'; z) = (x p ; y'; f(y')), where

[0109]

[0110] where y' is restricted to the interval

[0111]

[0112] The image values ​​along the trajectory are approximately constant, so only one point on the trajectory needs to be beamformed. Therefore, for a given virtual transmitter position, the reconstruction module can form a single beam from (x'; y p ; z) plane to calculate the image value of the entire 3-D LRV image, because any point in the volume can be mapped to this plane via the above equation. Assume that (y′,z)≠(y v ,z v ), mapping (x′,y′,z)→(x′,y p ,f(y p )) can be obtained through the following function:

[0113]

[0114] Since this function is independent of x', we only need to compute the mapping of the unique (y';z) coordinates. Therefore, assuming that the volume is of size N x’ N y’ N z To perform beamforming in a three-dimensional grid, we only need to calculate the mapping position N x’ N z In contrast, the existing method needs to calculate ToF N x’ N y’ N z N times.

[0115] In some embodiments, for different virtual source positions, the position of the image plane along the y′ axis is selected differently, preferably such that y p =y v , thereby avoiding the situation where the intersection of the trajectories is outside the trajectory domain defined by the above inequality. Nevertheless, in some embodiments, it is necessary to determine whether a given point in (x', y', z) is on a trajectory (the trajectory is also y' = y p limited), it can be asserted

[0116] |y p -y v |<|2z v -d((x′,y′,z),x′)|.

[0117] Another option is if z <z v , then we assert that f(y p ) <z v ; if z>z v , then we assert that f(y p )>z v . It is important to note that in some embodiments, it may not be necessary to assert the above conditions at all, as there may be several options to avoid these conditions. For example, in one embodiment, the process may derive two image planes, one for each solution in the conditional equation (1). With these two solutions for the image planes, the process may then reconstruct two 3-D LRVs. The process may then reconstruct two 3-D LRVs at z=z v In practice, one can also choose not to consider the domain of f(y'), because in ordinary synthetic aperture imaging, z v Stay away from the imaging area.

[0118] For plane wave imaging, the mapping function can be further simplified. First, the derivative of f(y') is calculated to obtain the simplified expression

[0119]

[0120] y v and z v Substitute r sin(φ) and -r cos(φ) respectively, and let r→∞

[0121] Conclusion

[0122]

[0123] Here, φ is the launch angle, and the equation states that the slope of the locus is half the slope along the launch wavefront. Therefore, the simplified expression for the locus is

[0124]

[0125] Still refer to Figure 4 , the device can then combine the volumetric ultrasound image information from multiple transmissions (i.e., different virtual transmitter positions) to obtain a spatially resolved volumetric ultrasound image, also called a high-resolution volumetric image, because it has a high spatial resolution in all three spatial directions. To this end, the processing pipeline also includes a combiner module 430, which receives a series of LRVs calculated by the reconstruction module 420 based on the series of beamformed 2-D images produced by the beamformer module 410. The combination module 430 then combines the LRVs to form a single HRV, for example, by summing the image values ​​of the LRVs (optionally weighted) at each image point, optionally followed by appropriate normalization.

[0126] In one variation, at least a portion of the processing pipeline 400 is implemented by a separate computing device distinct from the console. In this embodiment, the RF signals stored in the memory and / or the beamformed image planes stored in the memory can be loaded and processed by the processing pipeline 400 to generate the volumetric images described herein. Such a device may include a scan converter and a display for constructing and visually displaying a representation of the volumetric ultrasound image. Alternatively or additionally, the volumetric image can be transmitted to the system 102, another ultrasound system, and / or another computer device to construct and visually display a representation of the volumetric ultrasound image or otherwise process the volumetric ultrasound image.

[0127] Figure 7 An example method according to embodiments herein is shown.

[0128] The order of the following operations is for explanation purposes and is not restrictive. Therefore, one or more operations may be performed in different orders, including but not limited to being performed simultaneously. In addition, one or more operations may be omitted and / or one or more other operations may be added.

[0129] At S1 , ultrasonic waves are transmitted corresponding to a virtual transmitter position, as described herein and / or otherwise.

[0130] At S2 , an ultrasound signal corresponding to a virtual transmitter position is acquired, as described herein and / or otherwise.

[0131] It is understood that the S1 and S2 operations may be omitted. For example, in another case, a previously acquired and stored image is retrieved from a memory.

[0132] At S3 , the ultrasound signal is beamformed to produce a 2-D image, as described herein and / or otherwise.

[0133] At S4, the remaining 3-D image coordinates are mapped onto the plane of the 2-D image and their image values ​​are interpolated to generate a low resolution volume image (LRV) corresponding to the virtual emitter position.

[0134] Operations S1 to S4 are repeated for different virtual transmitter positions. The number of iterations depends on parameters such as the required resolution, the required update frequency, the size of the RCA, etc.

[0135] When all LRVs are generated, the process proceeds to S5 where the LRVs are combined into a single high resolution convolution image (HRV), as described herein or otherwise.

[0136] At S6, the created HRV is displayed and / or stored and / or otherwise processed, as described herein or otherwise. In addition, image information (such as detected objects, size, direction, volume flow, etc.) and / or derived quantities may be estimated and visualized.

[0137] When additional images need to be generated, the process returns to S1; otherwise the process may terminate.

[0138] The above contents can be implemented by computer-readable instructions, which are encoded or embedded in the memory 126 (i.e., computer-readable storage medium, excluding temporary media), and when the computer processor executes these instructions, the processor performs the operations described herein. Additionally or alternatively, at least one instruction in the computer-readable instructions is carried by a signal, carrier wave or other temporary medium (not a computer-readable storage medium).

[0139] In summary, various embodiments of the proposed RCA beamformer include a beamforming step and a reconstruction step. The beamforming step uses an RCA beamformer known in the art to reconstruct (x'; y p ; z) image plane is beamformed, and the reconstruction step maps the remaining coordinates onto this plane and interpolates its image values. It should be noted that in some embodiments, the z-axis may be sampled at least at the Nyquist frequency to allow accurate interpolation in the reconstruction. Alternatively, accurate reconstruction may be ensured in other ways, depending on the interpolation method used.

[0140] Since the reconstruction step is independent of the number of channels, beamforming can be done in only O(N x’ N y’ N z ), i.e., as the number of image points within the volume imaged by the 3D beamformed volume grows, the complexity of the prior art method is O(N x’ N y’ N zN), i.e., grows with the number of grid points in the 3D beamforming volume multiplied by the number of channels in the transducer array. Thus, embodiments of the apparatus disclosed herein greatly reduce computational complexity, particularly for large transducer arrays. Furthermore, in some embodiments, the complexity can be further reduced if desired. For example, since the trajectory need only be calculated for each unique (y'; z) coordinate, the calculated mapping can be stored in memory, eliminating the need to recalculate the mapping position for each volume realization. Alternatively, other optimizations may also be considered, such as using a GPU for calculations, depending on the computing hardware used. Thus, in some embodiments, instead of storing and reusing the mapping, dynamic calculation of the mapping may be used, thereby reducing memory requirements.

[0141] Finally, various embodiments of the processes disclosed herein also enable efficient, highly compressed image storage, since only the output of the beamforming step and position information (particularly virtual emitter positions) need to be stored to recover the volume.

[0142] Examples:

[0143] The performance of embodiments of the proposed RCA beamforming procedure disclosed herein was evaluated by performing guidewire and cyst phantom measurements using a cyst phantom designed for 3-D imaging.

[0144] The measurements were performed using a Vermon 128+128RCA probe connected to a Verasonics Vantage 256 research scanner and the simulations used the same transducer and sequence parameters. The parameters used for these measurements included:

[0145] -Number of components: 128++128

[0146] -Center frequency: 6MHz

[0147] - Transmit pulse period: 2

[0148] -Speed ​​of sound: 1540m / s

[0149] - Component pitch: 0.27mm

[0150] -Emissions per image: 192

[0151] - Pulse repetition frequency: 500Hz

[0152] - Transmit / receive apodization: von Hann

[0153] - Number of effective components: 32

[0154] - Transmit / Receive F quantity: -1 / 1

[0155] - Sampling frequency: 31.25MHz.

[0156] The imaging sequence used 96 defocused row shots and 96 defocused column shots, with a 32-element sliding aperture. The transmit and receive F numbers were set to -1 and 1, and RF data were acquired at a sampling rate of 31.25 MHz. p =y v For (x'; y p ; z) plane. Full 3-D reconstruction is performed from this plane using spline interpolation.

[0157] Fig.9A shows a 2-D slice of a volumetric B-mode image using a prior art beamforming method, while Fig. 9B Shown is a 2-D slice of a volumetric B-mode image taken using an embodiment of the beamforming method disclosed herein. Fig. 10A shows a 3-D rendering of a volumetric B-mode image using a prior art beamforming method, and Fig. 10B 3-D rendering of a volumetric B-mode image using an embodiment of the beamforming method disclosed herein is shown. Figure 9A-9B and Figure 10A-10B As can be seen in , the outputs from the two beamformers are visually indistinguishable. The beamformed volume correlation coefficient is calculated to be 99.80%.

[0158] By adding the average LRV beamforming time from 10 realizations to the increased L = N x =N y =N z = N values ​​to evaluate the computational complexity of the two beamforming methods. This means that in the analysis, the number of channels and samples in the side length of the beamforming volume increases simultaneously. It is also assumed that N x N y N z The axial sampling rate of the volume is sufficient for the proposed method.

[0159] Prior art RCA beamforming is performed using a CUDA C / C++ implementation of the RCA beamformer presented in MB Stuart, PM Jensen, JT R Olsen, AB Kristensen, M. Schou, B. Dammann, and JA Jensen, “Real-time volumetric synthetic aperturesoftware beamforming of row-column probe data”, IEEE Trans. Ultrason., Ferroelec., Freq. Contr., Vol. 68, No. 8, pp. 2608-2618, 2021. The reconstruction step is performed using MATLAB’s built-in interpolation functions without GPU acceleration. The interpolation method used by the RCA beamformer is cubic interpolation, while the full 3-D reconstruction as described previously is achieved using spline interpolation. Finally, the prior art and the proposed method are evaluated on a computer with an NVIDIA Quadro RTX 5000 graphics card and a 2.90GHz Intel Xeon Gold 6226R CPU.

[0160] Fig.11 A comparison of the computation time as a function of the number of samples and channels in the receive aperture is shown. The results assume that the beamforming step and the reconstruction step contain approximately the same number of samples along the axial side length. This assumption requires that N in the final beamforming volume z is higher than or equal to the sampling rate used in the beamforming step. Figure 1101 shows the computation time of the prior art RCA beamformer, while Figure 1102 shows the computation time of the method proposed in this article. As L increases, the computation time of the prior art RCA beamformer rapidly deviates from the computation time of the proposed RCA beamformer. For example, when L=64, the computation time of the prior art method is 12.31ms, while the proposed method achieves beamforming in 2.82ms. When L=500, the computation time of the prior art method is 32.15ms, while the proposed method performs beamforming in 0.75s. Moreover, in another more realistic test, based on the data acquired with 128+128RCA, the proposed beamformer is able to beamform N in 0.42s. x N y N z = 192 x 192 x 2000 LRV is beamformed and the prior art beamformer processes the volume in 3.36s.

[0161] At least some embodiments and / or aspects disclosed herein may be summarized as follows:

[0162] Embodiment 1: An ultrasonic imaging device for providing a volumetric ultrasonic image of an image volume, wherein the ultrasonic imaging device comprises:

[0163] a) a row-column addressed transducer array configured to convert an excitation electrical pulse into an ultrasonic pressure field, and to convert a received ultrasonic echo pressure field into an echo signal;

[0164] b) a beamformer module configured to beamform the echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume;

[0165] c) The reconstruction module is configured as follows:

[0166] - determining a set of trajectories, each trajectory intersecting an image point of said first set of image points,

[0167] - mapping a second set of image points of the image volume onto the first set of image points, and

[0168] - calculating corresponding image values ​​at mapped image points of the second group of image points based on the image values ​​of the image points of the first group of image points;

[0169] Embodiment 2: The ultrasonic imaging device according to embodiment 1 comprises a probe and a console operably coupled to the probe, wherein the probe comprises the row-column addressed transducer array.

[0170] Embodiment 3: An ultrasonic imaging device according to any one of the preceding embodiments, wherein the row-column addressed transducer array comprises a first group of transducer elements and a second group of transducer elements, the first group of transducer elements defines a first transducer array arranged along a first axis, and the second group of transducer elements defines a second transducer array arranged along a second axis.

[0171] Embodiment 4: The ultrasonic imaging device according to Embodiment 3 is configured to transmit ultrasonic waves through the first transducer array, and receive backscattered ultrasonic waves through the first transducer array or the second transducer array.

[0172] Embodiment 5: An ultrasonic imaging device according to any of the preceding embodiments, wherein each determined trajectory is defined by a constant position along the trajectory of a flight time from the virtual transmitter position to the closest position on the apertures of the receiving transducer elements of the first transducer array and the second transducer array.

[0173] Embodiment 6: An ultrasonic imaging device according to any one of the preceding embodiments, wherein the reconstruction module is configured to map each image coordinate of the image volume to the first set of image points and store a representation of the mapped image coordinates, wherein the reconstruction module is configured to use the stored representation of the mapped image coordinates to calculate multiple volume images.

[0174] Embodiment 7: An ultrasonic imaging device according to any one of the preceding embodiments, wherein the beamformer module is configured to perform delay and sum beamforming.

[0175] Embodiment 8: An ultrasonic imaging device according to any one of the preceding embodiments, wherein beamforming the echo signal using dynamic receive focusing includes, for each image point in the first group of image points, calculating the flight time of the shortest path from a virtual transmitter position to the image point and further from the image point to a receiving transducer element of the row-column addressed transducer array.

[0176] Embodiment 9: An ultrasonic imaging device according to any one of the preceding embodiments, wherein the first set of image points defines an image plane of a two-dimensional image within the image volume.

[0177] Embodiment 10: An ultrasonic imaging device according to Embodiment 9, wherein the image plane is a plane extending from a plane defined by the row-column addressed transducer array, in particular, a plane orthogonal thereto.

[0178] Embodiment 11: An ultrasonic imaging device according to any one of Embodiments 9 to 10, wherein the image plane is a plane orthogonal to the longitudinal direction of the receiving transducer elements of the row-column addressed transducer array.

[0179] Embodiment 12: An ultrasound imaging device according to any one of the preceding embodiments, configured to control the row-column addressed transducer array to perform multiple ultrasound transmissions corresponding to ultrasound transmitted from corresponding virtual transmitter positions; wherein the beamformer module and the reconstruction module are configured to calculate multiple low-resolution volume images, each low-resolution volume image corresponding to a corresponding virtual transmitter position, and wherein the imaging device further includes an image combiner module, which is configured to combine the multiple low-resolution volume images corresponding to different virtual transmitter positions into a combined high-resolution volume image, and the combined high-resolution volume image has a higher spatial resolution than the low-resolution volume image.

[0180] Embodiment 13: The ultrasonic imaging apparatus according to embodiment 12, wherein the beamformer module is configured to beamform the echo signals received from the row-column addressed transducer array in response to the transmission to generate a corresponding plurality of two-dimensional images, each two-dimensional image corresponding to one of the virtual transmitter positions; and wherein the reconstruction module is configured to calculate at least a first low-resolution volumetric image of the plurality of low-resolution volumetric images, the first low-resolution image corresponding to the first virtual transmitter position, at least by:

[0181] - determining a first set of trajectories to the position of said first virtual transmitter,

[0182] - mapping image coordinates of the image volume onto image locations of the first two-dimensional image using the first set of trajectories, and

[0183] - interpolating image values ​​at the mapped image coordinates from image values ​​of the first two-dimensional image plane, the interpolated image values ​​at the mapped image coordinates representing the first low-resolution volume image.

[0184] Embodiment 14: A method comprising:

[0185] - receiving an echo signal from the row-column addressed transducer array, the echo signal representing an ultrasound echo pressure field received by the row-column addressed transducer array in response to transmitting the ultrasound pressure field,

[0186] - beamforming the received echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume,

[0187] - determining a set of trajectories, each trajectory intersecting an image point of said first set of image points,

[0188] - mapping a second set of image points of the image volume onto the first set of image points, and

[0189] - calculating corresponding image values ​​at mapped image points of the second set of image points based on the image values ​​of the image points of the first set of image points.

[0190] Embodiment 15: A computer program comprising instructions, which, when executed by a data processing system, causes the data processing system to execute the steps of the method described in Embodiment 14.

[0191] Embodiment 16: A data processing system configured to execute the steps of the method described in Embodiment 14.

[0192] The present application has been described with reference to various embodiments. Others will make modifications and changes when reading this application. The present invention is intended to be interpreted as including all such modifications and changes as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. An ultrasound imaging device for providing a volumetric ultrasound image of an image volume, wherein: The ultrasonic imaging device comprises: a) a row-column addressed transducer array configured to convert an excitation electrical pulse into an ultrasonic pressure field and convert a received ultrasonic echo pressure field into an echo signal, wherein the row-column addressed transducer array comprises a first group of transducer elements and a second group of transducer elements, the first group of transducer elements defining a first transducer array arranged along a first axis, and the second group of transducer elements defining a second transducer array arranged along a second axis; b) a beamformer module configured to beamform the echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume; c) The reconstruction module is configured as follows: - determining a set of trajectories, each trajectory intersecting an image point of said first set of image points, wherein each of said determined trajectories is defined according to a virtual emitter position, - mapping a second set of image points of the image volume onto the first set of image points, and - calculating corresponding image values ​​at mapped image points of the second group of image points based on the image values ​​of the image points of the first group of image points; wherein the ultrasound imaging device is configured to control the row-column addressed transducer array to perform a plurality of ultrasound transmissions corresponding to ultrasound transmitted from corresponding virtual transmitter positions; wherein the beamformer module and the reconstruction module are configured to calculate a plurality of low-resolution volume images, each low-resolution volume image corresponding to a corresponding virtual transmitter position, and wherein the imaging device further comprises an image combiner module, the image combiner module being configured to combine the plurality of low-resolution volume images corresponding to different virtual transmitter positions into a combined high-resolution volume image, the combined high-resolution volume image having a higher spatial resolution than the low-resolution volume image.

2. The ultrasonic imaging apparatus according to claim 1, comprising a probe and a console operably coupled to the probe, wherein: The probe includes the row-column addressed transducer array.

3. An ultrasonic imaging device according to any one of the preceding claims, comprising a transmitting circuit, which is configured to generate an excitation electrical pulse to cause the row and column addressed transducer array to transmit a transmission sequence of ultrasonic pressure fields corresponding to corresponding virtual transmitter positions. 4 . The ultrasonic imaging device according to claim 1 , configured to transmit ultrasonic waves through the first transducer array and receive backscattered ultrasonic waves through the first transducer array or the second transducer array.

5. An ultrasonic imaging device according to any one of the preceding claims, wherein: Each of the determined trajectories is defined by a set of positions within the image volume, wherein a time of flight from the virtual transmitter position to a closest position on the apertures of the receiving transducer elements of the first and second transducer arrays is constant along the trajectory.

6. Ultrasonic imaging apparatus according to any one of the preceding claims, wherein: The reconstruction module is configured to map each image coordinate of the image volume onto the first set of image points and store a representation of the mapped image coordinates, wherein the reconstruction module is configured to calculate a plurality of volumetric images using the stored representation of the mapped image coordinates.

7. An ultrasonic imaging device according to any one of the preceding claims, wherein: The beamformer module is configured to perform delay-and-sum beamforming.

8. Ultrasonic imaging apparatus according to any one of the preceding claims, wherein: Beamforming the echo signals using dynamic receive focusing includes, for each image point in the first set of image points, calculating a flight time of a shortest path from a virtual transmitter position to the image point and further from the image point to a receive transducer element of the row-column addressed transducer array.

9. Ultrasonic imaging apparatus according to any one of the preceding claims, wherein: The first set of image points defines an image plane of a two-dimensional image within the image volume.

10. The ultrasonic imaging device according to claim 9, wherein: The image plane is a plane extending from, and in particular orthogonal to, a plane defined by the row-column addressed transducer array.

11. The ultrasonic imaging device according to any one of claims 9 to 10, wherein: The image plane is a plane orthogonal to the longitudinal direction of the receive transducer elements of the row-column addressed transducer array.

12. Ultrasonic imaging apparatus according to any one of the preceding claims, wherein: The beamformer module is configured to beamform echo signals received from the row-column addressed transducer array in response to the transmitting to produce a corresponding plurality of two-dimensional images, each two-dimensional image corresponding to one of the virtual transmitter positions; and wherein the reconstruction module is configured to compute at least a first low-resolution volumetric image of the plurality of low-resolution volumetric images, the first low-resolution image corresponding to a first virtual transmitter position by at least: - determining a first set of trajectories to the position of said first virtual transmitter, - mapping image coordinates of the image volume onto image locations of the first two-dimensional image using the first set of trajectories, and - interpolating image values ​​at the mapped image coordinates from image values ​​of the first two-dimensional image plane, the interpolated image values ​​at the mapped image coordinates representing the first low-resolution volume image.

13. An ultrasonic imaging device according to any one of the preceding claims, wherein: The reconstruction module is configured to determine each trajectory in the set of trajectories as a set of positions within the image volume, wherein a flight time from a virtual transmitter position via any one of the set of positions along the trajectory to a closest position on the apertures of the receiving transducer elements of the first transducer array and the second transducer array is constant along the trajectory.

14. A computer-implemented method comprising: - receiving an echo signal from a row-column addressed transducer array, the echo signal representing an ultrasound echo pressure field received by the row-column addressed transducer array in response to transmitting an ultrasound pressure field, - beamforming the received echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume, - determining a set of trajectories, each trajectory intersecting an image point of said first set of image points, - mapping a second set of image points of the image volume onto the first set of image points, and - calculating corresponding image values ​​at mapped image points of the second set of image points based on the image values ​​of the image points of the first set of image points.

15. A computer program comprising instructions which, when executed by a data processing system, cause the data processing system to perform the steps of the method according to claim 14.

16. A data processing system configured to perform the steps of the method according to claim 14.

17. An ultrasound imaging apparatus for providing a volumetric ultrasound image of an image volume, wherein: The ultrasonic imaging device comprises: d) a row-column addressed transducer array configured to convert an excitation electrical pulse into an ultrasonic pressure field, and to convert a received ultrasonic echo pressure field into an echo signal; e) a beamformer module configured to beamform the echo signals using dynamic receive focusing to generate corresponding image values ​​at a first set of image points within the image volume; f) Reconstruction module, configured as follows: - determining a set of trajectories, each trajectory intersecting an image point of said first set of image points, - mapping a second set of image points of the image volume onto the first set of image points, and - calculating corresponding image values ​​at mapped image points of the second set of image points based on the image values ​​of the image points of the first set of image points.

18. The ultrasonic imaging apparatus of claim 17, comprising a probe and a console operably coupled to the probe, wherein: The probe includes the row-column addressed transducer array.

19. The ultrasonic imaging device according to any one of claims 17 to 18, wherein: The row-column addressed transducer array includes a first set of transducer elements defining a first transducer array arranged along a first axis and a second set of transducer elements defining a second transducer array arranged along a second axis. 20 . The ultrasonic imaging apparatus according to claim 19 , configured to transmit ultrasonic waves through the first transducer array, and receive backscattered ultrasonic waves through the first transducer array or the second transducer array.

21. The ultrasonic imaging device according to any one of claims 17 to 20, wherein: Each of the determined trajectories is defined by a position wherein a time of flight from the virtual transmitter position to a closest position on the apertures of the receiving transducer elements of the first and second transducer arrays is constant along the trajectory.

22. The ultrasonic imaging device according to any one of claims 17 to 21, wherein: The reconstruction module is configured to map each image coordinate of the image volume onto the first set of image points and store a representation of the mapped image coordinates, wherein the reconstruction module is configured to calculate a plurality of volumetric images using the stored representation of the mapped image coordinates.

23. The ultrasonic imaging device according to any one of claims 17 to 22, wherein: The beamformer module is configured to perform delay-and-sum beamforming.

24. The ultrasonic imaging device according to any one of claims 17 to 23, wherein: Beamforming the echo signals using dynamic receive focusing includes, for each image point in the first set of image points, calculating a flight time of a shortest path from a virtual transmitter position to the image point and further from the image point to a receive transducer element of the row-column addressed transducer array.

25. The ultrasonic imaging device according to any one of claims 17 to 24, wherein: The first set of image points defines an image plane of a two-dimensional image within the image volume.

26. The ultrasonic imaging device according to claim 25, wherein: The image plane is a plane extending from, and in particular orthogonal to, a plane defined by the row-column addressed transducer array.

27. The ultrasonic imaging device according to any one of claims 25 to 26, wherein: The image plane is a plane orthogonal to the longitudinal direction of the receive transducer elements of the row-column addressed transducer array.

28. The ultrasonic imaging device according to any one of claims 17 to 27, configured to control the row-column addressed transducer array to perform a plurality of ultrasound transmissions corresponding to ultrasound transmitted from corresponding virtual transmitter positions; wherein, The beamformer module and the reconstruction module are configured to compute a plurality of low-resolution volumetric images, each low-resolution volumetric image corresponding to a respective virtual emitter position, and wherein the imaging device further comprises an image combiner module configured to combine the plurality of low-resolution volumetric images corresponding to different virtual emitter positions into a combined high-resolution volumetric image, the combined high-resolution volumetric image having a higher spatial resolution than the low-resolution volumetric images.

29. The ultrasonic imaging device according to claim 28, wherein: The beamformer module is configured to beamform echo signals received from the row-column addressed transducer array in response to the transmitting to produce a corresponding plurality of two-dimensional images, each two-dimensional image corresponding to one of the virtual transmitter positions; and wherein the reconstruction module is configured to compute at least a first low-resolution volumetric image of the plurality of low-resolution volumetric images, the first low-resolution image corresponding to a first virtual transmitter position by at least: - determining a first set of trajectories to the position of said first virtual transmitter, - mapping image coordinates of the image volume onto image locations of the first two-dimensional image using the first set of trajectories, and - interpolating image values ​​at the mapped image coordinates from image values ​​of the first two-dimensional image plane, the interpolated image values ​​at the mapped image coordinates representing the first low-resolution volume image.

30. An ultrasonic imaging apparatus according to any one of claims 17 to 29; each of the determined trajectories being defined in terms of a virtual transmitter position.

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