arXiv subjects

Scott Schoen Jr

Publications and source records attributed to Scott Schoen Jr.

5 recordsLinked to original sources

arXiv2025

Wavefield Correlation Imaging in Arbitrary Media with Inherent Aberration Correction

Ultrasound (US) imaging is an indispensable tool for diagnostic imaging, particularly given its cost, safety, and portability profiles compared to other modalities. However, US is challenged in subjects with morphological heterogeneity (e.g., those with overweight or obesity), largely because conventional imaging algorithms do not account for such variation in the beamforming process. Specific knowledge of the these spatial variations enables supplemental corrections of these algorithms, but with added computational complexity. Wavefield correlation imaging (WCI) enables efficient image formation in the spatial frequency domain that, in its canonical formulation, assumes a uniform medium. In this work, we present an extension of WCI to arbitrary known speed-of-sound distributions directly in the image formation process, and demonstrate its feasibility in silico, in vitro, and in vivo. We report resolution improvements of over 30% and contrast improvements of order 10% over conventional WCI imaging. Together our results suggest heterogeneous WCI (HWCI) may have high translational potential to improve the objective quality, and thus clinical utility, of ultrasound images.

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arXiv2024

Efficient Aberration Correction via Optimal Bulk Speed of Sound Compensation

Diagnostic ultrasound is a versatile and practical tool in the abdomen, and is particularly vital toward the detection and mitigation of early-stage non-alcoholic fatty liver disease (NAFLD). However, its performance in those with obesity -- who are at increased risk for NAFLD -- is degraded due to distortions of the ultrasound as it traverses thicker, acoustically heterogeneous body walls (aberration). Many aberration correction methods for ultrasound require measures of channel data relationships. Simpler, bulk speed of sound optimizations based on the image itself have demonstrated empirical efficacy, but their analytical limitations have not been evaluated. Herein, we assess analytically the bounds of a single, optimal speed of sound correction in receive beamforming to correct aberration, and improve the resulting images. Additionally, we propose an objective metric on the post-sum B-mode image to identify this speed of sound, and validate this technique through in virto phantom experiments and in vivo abdominal ultrasound data collection with physical aberrating layers. We find that a bulk correction may approximate the aberration profile for layers of relevant thicknesses (1 to 3 cm) and speeds of sound (1400 to 1500 m/s). Additionally, through in vitro experiments, we show significant improvement in resolution (average point target width reduced by 60 %) and improved boundary delineation in vivo with bulk speed of sound correction determined automatically from the beamformed images. Together, our results demonstrate the utility of simple, efficient bulk speed of sound correction to improve the quality of diagnostic liver images.

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arXiv2020

Morphological Reconstruction Improves Microvessel Mapping in Super-Resolution Ultrasound

Generation of super-resolution (SR) ultrasound (US) images, created from the successive local-ization of individual microbubbles in the circulation, has enabled the visualization of microvascular structure and flow at a level of detail that was not possible previously. Despite rapid progress, tradeoffs between spatial and temporal resolution may challenge the translation of this promising technology to the clinic. To temper these trade-offs, we propose a method based on morphological image reconstriction. This method can extract from ultrafast contrast-enhanced ultrasound (CEUS) images hundreds of microbubble peaks per image (312-by-180 pixels) with intensity values varying by an order of magnitude. Specifically, it offers a fourfold increase in the number of peaks detected per frame, requires on the order of 100 ms for processing, and is robust to additive electronic noise (down to 3.6 dB CNR in CEUS images). By integrating this method to a SR framework we demonstrate a 6-fold improvement in spatial resolution, as compared to CEUS, in imaging chicken embryo microvessels. This method that is computationally efficient and, thus, scalable to large data sets, may augment the abilities of SR-US in imaging microvascular structure and function.

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arXiv2020

Acoustic Source Localization with the Angular Spectrum Approach in Continuously Stratified Media

The angular spectrum approach (ASA)---a fast, frequency domain method for calculation of the acoustic field---enables passive source localization and modeling forward propagation in homogeneous media with high computational efficiency. Here we show that, if the medium is continuously stratified, a first-order analytical solution may be obtained for the field at arbitrary depth. Our simulations show that the stratified ASA solution enables accurate source localization as compared to the uncorrected ASA (error from 1.2$\pm$0.3 to 0.49$\pm$0.3 wavelengths) at scalings relevant to biomedical ($kL \sim$ 500, where $L$ is the length of the measurement aperture), underwater ($kL \sim$ 800), and atmospheric ($kL \sim$ 10) acoustic applications. Overall the total computation was on the order milliseconds on standard hardware (225$\pm$84 ms, compared with $78\pm63$ ms for the homogeneous ASA formulation over all cases). Collectively, the results suggest the proposed ASA phase correction enables efficient and accurate method for source localization in continuously stratified environments.

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arXiv2019

Heterogeneous Angular Spectrum Approach for Trans-skull Imaging and Focusing

Ultrasound, alone or in concert with circulating microbubble contrast agents, has emerged as a promising modality for therapy and imaging of brain diseases. While this has become possible due to advancements in aberration correction methods, a range of applications, including adaptive focusing and tracking of the microbubble dynamics through the human skull, may benefit from even more computationally efficient methods to account for skull aberrations. Here, we derive a general method for the angular spectrum approach (ASA) in a heterogeneous medium, based on a numerical marching scheme to approximate the full implicit solution. We then demonstrate its functionality with simulations for (human) skull-related aberration correction and trans-skull passive acoustic mapping. Our simulations show that the general solution provides accurate trans-skull focusing as compared to the uncorrected case for clinically relevant frequencies, apertures, and targets, with the effects of skull attenuation and amplitude shading included. In the case of source localization, our method leads to an average of 75 % error reduction and 40 to 60 % increase in peak intensity, evaluated over the range of frequencies as compared to the homogeneous medium ASA. Overall, total computation times for both focusing and point source localization of the order milliseconds can be attained with this approach. Collectively our findings indicate that the proposed phase correction method based on the ASA could provide a computationally efficient and accurate method for trans-skull transmit focusing and imaging of point scatterers, potentially opening new possibilities for treatment and diagnosis of brain diseases.

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