Receive/Transmit Aperture Selection for 3D Ultrasound Imaging with a 2D Matrix Transducer

Abstract

Recently, we realized a prototype matrix transducer consisting of 48 rows of 80 elements on top of a tiled set of Application Specific Integrated Circuits (ASICs) implementing a row-level control connecting one transmit/receive channel to an arbitrary subset of elements per row. A fully sampled array data acquisition is implemented by a column-by-column (CBC) imaging scheme (80 transmit-receive shots) which achieves 250 volumes/second (V/s) at a pulse repetition frequency of 20 kHz. However, for several clinical applications such as carotid pulse wave imaging (CPWI), a volume rate of 1000 per second is needed. This allows only 20 transmit-receive shots per 3D image. In this study, we propose a shifting aperture scheme and investigate the effects of receive/transmit aperture size and aperture shifting step in the elevation direction. The row-level circuit is used to interconnect elements of a receive aperture in the elevation (row) direction. An angular weighting method is used to suppress the grating lobes caused by the enlargement of the effective elevation pitch of the array, as a result of element interconnection in the elevation direction. The effective aperture size, level of grating lobes, and resolution/sidelobes are used to select suitable reception/transmission parameters. Based on our assessment, the proposed imaging sequence is a full transmission (all 80 elements excited at the same time), a receive aperture size of 5 and an aperture shifting step of 3. Numerical results obtained at depths of 10, 15, and 20 mm show that, compared to the fully sampled array, the 1000 V/s is achieved at the expense of, on average, about two times wider point spread function and 4 dB higher clutter level. The resulting grating lobes were at −27 dB. The proposed imaging sequence can be used for carotid pulse wave imaging to generate an informative 3D arterial stiffness map, for cardiovascular disease assessment.

Multi-angle data acquisition to compensate transducer finite size in photoacoustic tomography

“…Video-rate imaging can be achieved using ring arrays, but spatial aliasing and arc artifacts may occur due to the pitch size (the spacing between the array elements); the pitch must be lower than half of the wavelength at the central frequency of the array [45] . This necessitates a very large number of elements, read-out circuits and cables, which impose manufacturing difficulties and setup complexities [42] , [46] , [47] , [48] . Further development of our data acquisition strategy in combination with ring arrays could remove the rotation step in our approach and possibly mitigate the effects of aliasing and arc artifacts caused by the large pitch size of the current ring arrays [13] , [14] .…”

“…In MA-PAT, for each central rotation, the RF data is back-projected considering the transducer directivity pattern to reduce the number of spatial samples, clutter artifacts and aliasing [42] . Therefore, the virtual detector (resembling the combination of all central rotations around the axis of the transducer at a spatial sample) is called a directional virtual detector in our study.…”

The Core of Medical Imaging: State of the Art and Perspectives on the Detectors

“…Going from 2D to 3D ultrasound imaging, a 2D matrix transducer is required, entailing fabrication and implementation problems [6]. This is the reason why 3D ultrasound imaging methods based on 2-D array probes are continuing to improve in terms of fabrication and processing [7,8], and synthetic aperture ultrasound imaging [9,10]. Recently, the combination of miniaturized phased-array transducers and minimally invasive robotic surgery instruments is a further challenge in array development; preliminary phantom measurements demonstrate the feasibility to provide intraoperative image guidance and tissue characterization during endoscopic procedures [11].…”

Transcranial Ultrasound Imaging with Estimating the Geometry, Position and Wave-Speed of Temporal Bone

“…where, is the output of the beamformer at pixel , and are the number of transmissions and receivers, respectively, is the recorded data, and are the transmit and receive travel times, respectively, and ( , , ) W P i j is a weight calculated for pixel . In this paper, this weight is based on the far field directivity of the elements of the array [30,31]. To accurately reconstruct the images, the phase aberration caused by the skull (directly affecting the arrival times used for beamforming) should be taken into account.…”