ω- k Algorithm for Sparse-Transmit Sparse-Receive Diverging Beam Synthetic Aperture Transmit Scheme
03 Jun 2020-IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 67, Iss: 10, pp 2046-2056
TL;DR: A fast and efficient frequency–wavenumber algorithm for the sparse DBSAT scheme and an additional novel step of recovering missing frame data due to sparse transmit is introduced, namely, projection onto elliptical sets (POES).
Abstract: In synthetic aperture (SA) imaging reported in the ultrasound imaging literature, typically, the delay and sum (DAS) beamformer is used; however, it is computationally expensive due to the pixel-by-pixel processing performed in the time domain. Recently, the adaptation of frequency-domain beamformers for medical ultrasound SA imaging, particularly to single-element/multielement synthetic transmit aperture (STA/MSTA) schemes, has been reported. In such reports, usually, less attention is paid to reducing system complexity. Recently, a sparse-transmit sparse-receive version of diverging beam-based synthetic aperture technique (DBSAT) was shown to achieve a reduction in system complexity by using fewer parallel receive channels, yet it achieves better quality and higher frame rate than conventional focused beamforming. However, this was also demonstrated using the DAS beamformer. In this work, we aim at achieving a reduction in computational cost, in addition to a reduction in system complexity, by implementing a fast and efficient frequency–wavenumber ( $\omega $ - ${k}$ ) algorithm for the sparse DBSAT scheme. In doing so, an additional novel step of recovering missing frame data due to sparse transmit is introduced, namely, projection onto elliptical sets (POES). The results from this novel combination of $\omega $ - ${k}$ with POES recovery showed that it is feasible to achieve several orders of magnitude faster reconstruction compared with the standard DAS beamforming, without any compromise in the image quality and, in some cases, with improved image quality. The average value of the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) calculated from cyst at 15-mm depth obtained using the different schemes was 4.94 and 5.73 dB better when $\omega $ - ${k}$ was employed instead of DAS, respectively. In addition, for the sparse data set acquired with a 50% overlap during transmit and 64 active receive elements, DAS reconstruction takes as long as ~647 s, whereas the $\omega $ - ${k}$ algorithm takes only ~2 s when programmed and executed in MATLAB.
Citations
More filters
TL;DR: In this article , a sparse-transmit scheme (with only 8 transmits) on Synthetic Transmit Aperture technique (sparse STA) was chosen to evaluate the beamformers ability to generate the high-resolution Ultrasound image.
6 citations
TL;DR: In this paper , the authors proposed two Fourier-domain beamformers (vs1 and vs2) for non-steered diverging wave imaging and an explicit interpolation scheme for virtual-source-based steered divergence wave imaging using a convex probe.
Abstract: Convex probes have been widely used in clinical abdominal imaging for providing deep penetration and wide field of view. Ultrafast imaging modalities have been studied extensively in the ultrasound community. Specifically, broader wavefronts, such as plane wave and spherical wave, are used for transmission. For convex array, spherical wavefront can be simply synthesized by turning all elements simultaneously. Due to the lack to transmit focus, the image quality is suboptimal. One solution is to adopt virtual sources behind the transducer and compound corresponding images. In this work, we propose two novel Fourier-domain beamformers (vs1 and vs2) for nonsteered diverging wave imaging and an explicit interpolation scheme for virtual-source-based steered diverging wave imaging using a convex probe. The received echoes are first beamformed using the proposed beamformers and then interpolated along the range axis. A total of 31 virtual sources located on a circular line are used. The lateral resolution, the contrast ( C ), and the contrast-to-noise ratio (CNR) are evaluated in simulations, phantom experiments, ex vivo imaging of the bovine heart, and in vivo imaging of the liver. The results show that the two proposed Fourier-domain beamformers give higher contrast than dynamic receive focusing (DRF) with better resolution. In vitro results demonstrate the enhancement on CNR: 6.7-dB improvement by vs1 and 5.9-dB improvement by vs2. Ex vivo imaging experiments on the bovine heart validate the CNR enhancements by 8.4 dB (vs1) and 8.3 dB (vs2). In vivo imaging on the human liver also reveals 6.7- and 5.5-dB improvements of CNR by vs1 and vs2, respectively. The computation time of vs1 and vs2, depending on the image pixel number, is shortened by 2-73 and 4-216 times than the DRF.
3 citations
References
More filters
TL;DR: In this article, the authors proposed to decompose the measured field into monochromatic plane waves of appropriate amplitudes, wave lengths and propagation directions, and their recombination at the time when the sounding pulse was emitted, can produce a map of the backscattered electromagnetic field.
Abstract: Synthetic aperture radar (SAR) data focusing has been traditionally performed using matched filter techniques. However, downward continuation techniques can produce, with a great computational efficiency, results that only the most sophisticated conventional techniques can achieve. The basic idea is to decompose the measured field into monochromatic plane waves of appropriate amplitudes, wave lengths and propagation directions. The backpropagation of these plane waves, and their recombination at the time when the sounding pulse was emitted, can produce a map of the backscattered electromagnetic field. In order to obtain correct focusing of synthetic aperture radar raw data, both the geometrical and the transmission parameters of the system should be known as precisely as possible. The transmission parameters are generally known very precisely, whereas the geometrical ones (i.e. sensor-target relative position, satellite velocity and attitude, etc.) can be derived from the ephemerides of the satel...
58 citations
01 Jan 1994
TL;DR: By replacing the two-way imaging system with a one-way array of virtual elements, complete subsets of the synthetic focus dataset can be readily identified and can be used to significantly reduce the data acquisition requirements for synthetic focus imaging, leading to the possibility of very high frame rate imaging.
Abstract: Synthetic focus is a method of constructing images from the signals associated with each pair of transmit/receive elements of a two-way transducer array. Using conventional aperture designs, synthetic focus datasets contain significant redundancy. The redundancy is exact in the far field, and is approximate in the near field. By replacing the two-way imaging system with a one-way array of virtual elements, complete subsets of the synthetic focus dataset can be readily identified. These complete subsets contain all the information necessary to construct images. These techniques can also be used to significantly reduce the data acquisition requirements for synthetic focus imaging, leading to the possibility of very high frame rate imaging. Performance using partial datasets is compared with that of full datasets through simulations
49 citations
Journal Article•
TL;DR: The paper describes the use of synthetic transmit aperture (STA) imaging in medical ultrasound with a single element transmitting and all elements receiving apertures and the 2D ultrasound images of wire phantom are presented to demonstrate the benefits of SA imaging.
Abstract: The paper describes the use of synthetic transmit aperture
(STA) imaging in medical ultrasound. The synthetic aperture (SA) imaging is a
novel approach to today's commercial systems. In these systems the image is
acquired sequentially one image line at a time that puts a strict limit on the
frame rate and the possibility of acquiring a sufficient amount of data for high
image quality. This limitation can be lifted by employing SA imaging where the
data are acquired simultaneously from all directions over a number of emissions,
and the full image can be reconstructed from those data. Due to the complete
data set, it is possible to have full transmitting and receiving focusing at the
entire image region to improve the contrast dynamic and spatial resolution. The
paper describes the STA imaging with a single element transmitting and all
elements receiving apertures. In experiments, 32-element linear transducer array
with 0.48 mm inter-element spacing and a burst pulse of 100ns duration were
used. The single element transmission aperture was used to generate a spherical
wave covering the full image region. The 2D ultrasound images of wire phantom
are presented to demonstrate the benefits of SA imaging.
47 citations
"ω- k Algorithm for Sparse-Transmit ..." refers background in this paper
...This transmit–receive sequence is repeated until all elements of the transducer have transmitted [4]–[7]....
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TL;DR: The results confirm applicability of FBV in ultrasound, and 20 times less processing time is attained in comparison with DAS, while providing a more efficient algorithm with20 times less computations.
Abstract: An efficient Fourier beamformation algorithm is presented for multistatic synthetic aperture ultrasound imaging using virtual sources. The concept is based on the frequency domain wavenumber algorithm from radar and sonar and is extended to a multielement transmit/receive configuration using virtual sources. Window functions are used to extract the azimuth processing bandwidths and weight the data to reduce side lobes in the final image. Field II simulated data and SARUS (Synthetic Aperture Real-time Ultrasound System) measured data are used to evaluate the results in terms of point spread function, resolution, contrast, signal-to-noise ratio, and processing time. Lateral resolutions of 0.53 and 0.66 mm are obtained for Fourier Beamformation Using Virtual Sources (FBV) and delay and sum (DAS) on point target simulated data. Corresponding axial resolutions are 0.21 mm for FBV and 0.20 mm for DAS. The results are also consistent over different depths evaluated using a simulated phantom containing several point targets at different depths. FBV shows a better lateral resolution at all depths, and the axial and cystic resolutions of −6, −12, and −20 dB are almost the same for FBV and DAS. To evaluate the cyst phantom metrics, three different criteria of power ratio, contrast ratio, and contrast-to-noise ratio have been used. Results show that the algorithms have a different performance in the cyst center and near the boundary. FBV has a better performance near the boundary; however, DAS is better in the more central area of the cyst. Measured data from phantoms are also used for evaluation. The results confirm applicability of FBV in ultrasound, and 20 times less processing time is attained in comparison with DAS. Evaluating the results over a wide variety of parameters and having almost the same results for simulated and measured data demonstrates the ability of FBV in preserving the quality of image as DAS, while providing a more efficient algorithm with 20 times less computations.
36 citations
"ω- k Algorithm for Sparse-Transmit ..." refers methods in this paper
...[27], we perform a wrapping around delay operation along each frame’s...
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...The methodology for calculating theoretical values of computational cost has been derived and described in [27] and [43]....
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...In [27], the ω-k algorithm was modified for diverging beam transmission with a virtual source behind the transducer by using a specific methodology to rearrange the full aperture 3-D data....
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...The equations required for performing Stolt migration on MSTA with virtual source behind the transducer have been derived in detail in [16], [18], [27], and [39]....
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...observed and reported in the prior literature that employs this beamforming method [27]....
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TL;DR: This paper investigates two compressed sensing approaches that can be used to reconstruct 3-D synthetic aperture radar (SAR) images with undersampled measurements, and demonstrates that the Stolt-CS contributes little to image quality improvement or computational complexity reduction, while the NUFFT-CS achieves a good tradeoff between the reconstruction quality and the computational costs.
27 citations
"ω- k Algorithm for Sparse-Transmit ..." refers background in this paper
...the nonuniform fast Fourier transform (FFT) reconstruction on undersampled 3-D SAR data has been explored [34]....
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