Sparse array imaging with spatially-encoded transmits

Chiao, Richard Y.; Thomas, Lewis J.; Silverstein, S.D.

doi:10.1109/ultsym.1997.663318

Cited by 118 publications

(63 citation statements)

References 7 publications

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“…Hadamard encoding (Chiao et al 1997) was used to spatially encode the waveforms, where the Hadamard matrix was multiplied to the waveforms for the multiple transmissions (128 transmissions using 128 elements) and where all elements were used in receiving. The ultrasound acquisition lasted 2 s. This type of spatiotemporal encoding allowed virtual focusing in posttreatment by combining the RF data issue from the different transmissions.…”

Section: Ultrasound Acquisitionsmentioning

confidence: 99%

Robust sound speed estimation for ultrasound-based hepatic steatosis assessment

et al. 2017

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Hepatic steatosis is a common condition, the prevalence of which is increasing along with non-alcoholic fatty liver disease (NAFLD). Currently, the most accurate noninvasive imaging method for diagnosing and quantifying hepatic steatosis is MRI, which estimates the proton-density fat fraction (PDFF) as a measure of fractional fat content. However, MRI suffers several limitations including cost, contra-indications and poor availability. Although conventional ultrasound is widely used by radiologists for hepatic steatosis assessment, it remains qualitative and operator dependent. Interestingly, the speed of sound within soft tissues is known to vary slightly from muscle (1.575 mm • µs −1 ) to fat (1.450 mm • µs −1 ). Building upon this fact, steatosis could affect liver sound speed when the fat content increases. The main objectives of this study are to propose a robust method for sound speed estimation (SSE) locally in Institute of Physics and Engineering in Medicine

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Section: Ultrasound Acquisitionsmentioning

confidence: 99%

Robust sound speed estimation for ultrasound-based hepatic steatosis assessment

et al. 2017

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“…In synthetic transmit aperture (STA) imaging [4,5] a single element is used to transmit a spherical wave that occupies the entire region of interest. The backscattered signals are registered using a multi-element receive aperture and RF-samples from all channels are stored.…”

Section: Introductionmentioning

confidence: 99%

Sequential beamforming for synthetic aperture imaging

2013

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a b s t r a c tSynthetic aperture sequential beamforming (SASB) is a novel technique which allows to implement synthetic aperture beamforming on a system with a restricted complexity, and without storing RF-data. The objective is to improve lateral resolution and obtain a more depth independent resolution compared to conventional ultrasound imaging. SASB is a two-stage procedure using two separate beamformers. The initial step is to construct and store a set of B-mode image lines using a single focal point in both transmit and receive. The focal points are considered virtual sources and virtual receivers making up a virtual array. The second stage applies the focused image lines from the first stage as input data, and take advantage of the virtual array in the delay and sum beamforming. The size of the virtual array is dynamically expanded and the image is dynamically focused in both transmit and receive and a range independent lateral resolution is obtained. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The lateral resolution increases with a decreasing F#. Grating lobes appear if F# 6 2 for a linear array with k-pitch. The performance of SASB with the virtual source at 20 mm and F# = 1.5 is compared with conventional dynamic receive focusing (DRF). The axial resolution is the same for the two methods. For the lateral resolution there is improvement in FWHM of at least a factor of 2 and the improvement at À40 dB is at least a factor of 3. With SASB the resolution is almost constant throughout the range. For DRF the FWHM increases almost linearly with range and the resolution at À40 dB is fluctuating with range. The theoretical potential improvement in SNR of SASB over DRF has been estimated. An improvement is attained at the entire range, and at a depth of 80 mm the improvement is 8 dB.

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“…The synthetic aperture technique synthesizes a larger aperture from measurements carried out using apertures located at different positions. Synthetic aperture can be divided into two major groups; the synthetic receive aperture, where a larger receive aperture is synthesized, and the synthetic transmit aperture, 9 where a larger transmit aperture is synthesized. The basic principle of synthetic transmit aperture is that a single point source emits a spherical wave, insonifying the entire image region.…”

Section: Introductionmentioning

confidence: 99%

Preliminary comparison of 3D synthetic aperture imaging with Explososcan

et al. 2012

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Explososcan is the 'gold standard' for real-time 3D medical ultrasound imaging. In this paper, 3D synthetic aperture imaging is compared to Explososcan by simulation of 3D point spread functions. The simulations mimic a 32x32 element prototype transducer. The transducer mimicked is a dense matrix phased array with a pitch of 300 µm, made by Vermon. For both imaging techniques, 289 emissions are used to image a volume spanning 60• in both the azimuth and elevation direction and 150 mm in depth. This results for both techniques in a frame rate of 18 Hz. The implemented synthetic aperture technique reduces the number of transmit channels from 1024 to 256, compared to Explososcan. In terms of FWHM performance, was Explososcan and synthetic aperture found to perform similar. At 90 mm depth is Explososcan's FWHM performance 7 % better than that of synthetic aperture. Synthetic aperture improved the cystic resolution, which expresses the ability to detect anechoic cysts in a uniform scattering media, at all depths except at Explososcan's focus point. Synthetic aperture reduced the cyst radius, R 20dB , at 90 mm depth by 48 %. Synthetic aperture imaging was shown to reduce the number of transmit channels by four and still, generally, improve the imaging quality.

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Sparse array imaging with spatially-encoded transmits

Cited by 118 publications

References 7 publications

Robust sound speed estimation for ultrasound-based hepatic steatosis assessment

Robust sound speed estimation for ultrasound-based hepatic steatosis assessment

Sequential beamforming for synthetic aperture imaging

Preliminary comparison of 3D synthetic aperture imaging with Explososcan

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