Volumetric ultrasound imaging with row-column addressed 2-D arrays using Spatial Matched Filter beamforming

Abstract

Abstract-For 3-D ultrasound imaging with row-column addressed 2-D arrays, the two orthogonal 1-D transmit and receive arrays are both used for one-way focusing in the lateral and elevation directions separately and since they are not in the same plane, the two-way focusing is the same as one-way focusing. However, the achievable spatial resolution and contrast of the B-mode images in Delay and Sum (DAS) beamforming are limited by the aperture size and by the operating frequency. This paper, investigates Spatial Matched Filter (SMF) beamforming on row-column addressed 2-D arrays to increase spatial resolution. The performance is investigated on both simulated and experimentally collected 3-D data by comparing the Point Spread Functions (PSFs) and the phantom images obtained with standard DAS and with SMF. Results show that the SMF beamformer outperforms DAS in both simulated and experimental trials and that a higher contrast resolution can be achieved by SMF beamforming (i.e., narrower main lobe and lower side lobes). The 6dB, 20dB and 40dB cystic resolution for a DAS simulated PSF at (0,0,30)mm are 1.22mm, 3.54mm and 7.46mm, for SMF beamforming they are 1.11mm, 2.33mm and 5.42mm accordingly. For measured RF-data of an iron needle facing toward the transducer positioned at (0,0,32.5)mm along the central axis, the 6dB, 20dB and 40dB cystic resolution for DAS beamforming are 1.99mm, 2.19mm and 4.26mm, and they are 0.8mm, 2.06mm and 4.18mm for SMF beamforming accordingly. SMF beamforming increases the contrast resolution which turns into a better quality of the B-mode images.

Pushing the boundaries of optoacoustic microscopy by total impulse response characterization

“…In contrast, in the TIR-SMF approach (Fig. 6b), filtered and averaged optoacoustic data were cross-correlated with the corresponding signals of SOAPs at the identical spatial positions 39 . After cross-correlation, A-scans were superimposed in time and space.…”

Imaging Performance for Two Row–Column Arrays

“…As an alternative to dynamic receive focusing using DAS beamforming, the signal from each channel of an array can be spatially matched filtered to align its output with that from the other channels [24]- [26], [29]. This was suggested by Yen [26] for use on RCA arrays.…”

Large-Pitch Methods for 2D/3D Synthetic Transmit Aperture Ultrasound Imaging

“…The spatial matched filter (SMF) method has been investigated for different applications and was first introduced to conventional B-mode [76]. Further investigations using the SMF were done for the row-column addressed array [77] and synthetic aperture sequential beamforming (SASB) [78]. The SMF is constructed based on the system transmit and receive spatial impulse responses at each imaging point.…”

“…Thus, the image quality can be improved compared to other combinations with similar M. In the beamforming process, we used an analytical SRF applied to LPSTA to partially compensate the contrast deterioration in the reconstructed images due to the SAPs applied in transmit and receive. The SRF of the spatial matched filter method has been used in B-mode [75], [76] and row-column addressed array [77] and synthetic aperture sequential beamforming (SASB) [78]. In this Chapter, we applied it to LPSTA and derived an analytical expression for the beam pattern based on a far-field approximation.…”

“…Normally, to calculate the geometry distance using a standard DAS approach, it is assumed that the transmitter and receiver are a point source, in which the impulse response can be represented as a Delta function [75], [77]. However, when the transmit and receive elements are combined as SAPs, the Dirac delta function representation is a poor approximation.…”