3D full-waveform inversion in ultrasound computed tomography employing a ring-array

Abstract

Ultrasound computed tomography (USCT) is an emerging medical imaging modality that holds great promise for breast cancer diagnosis. Full-waveform inversion (FWI)-based image reconstruction methods for USCT can produce high spatial resolution and accurate images of the acoustic properties of soft tissues. A common USCT design employs a circular ring-array comprised of elevation-focused ultrasonic transducers. Volumetric imaging can be achieved by translating the ring-array orthogonally to the imaging plane. Slice-by-slice two-dimensional (2D) reconstruction methods have been implemented to form a composite three-dimensional (3D) volumes by stacking together reconstructed cross-sectional images at each ring-array position. However, this 2D approach does not account for the 3D wave propagation physics and the focusing properties of the transducers, and can result in out-of-plane scattering-based artifacts and inaccuracies. To overcome this, a new 3D time-domain FWI method is proposed for ring-array-based USCT that concurrently utilizes measurement data acquired from multiple positions of the ring-array. A virtual imaging study of ring-array-based USCT that employs a realistic 3D numerical breast phantom was conducted to assess the impact of the number of ring-array measurements on image quality.

A Forward Model Incorporating Elevation-Focused Transducer Properties for 3-D Full-Waveform Inversion in Ultrasound Computed Tomography

“…As such, the images reconstructed by use of the 2-D method appear sharp but contain conspicuous artifacts due to the modeling error involved. This motivates the development of new algorithms incorporating USCT data corresponding to multiposition of the ring-array to further improve the spatial resolution of 3-D reconstruction [74].…”

“…The NBPs and computer-simulated pressure traces used in the case study have been released under Public Domain CC-0 dedication and are available for download from [ 41 ].…”

“…This demonstrates, for the first time, the feasibility of incorporating transducer elevational focusing effects in a 3-D time-domain FWI reconstruction method for ring-array-based USCT and reveals improvements in image quality over the traditional SBS reconstruction approach. To enable related investigations by other researchers, the 3-D NBPs and corresponding 3-D USCT measurement data used in the case study have been made publicly available under CC-0 licensing [ 41 ].…”

Tomografia de mama por ultrassom usando um modelo de elementos finitos.

“…The idea of stacking slices of the object, or layer by layer tomography, is the method used, for instance, in [23,24,25,26,27,28], published around ten years ago, and also in the very recent [29,30] and [31] which, albeit using transducers located in a circular ring that moves perpendicularly to the slice plane, started to account for 3D effects using transducer focusing. Each of the transducers are arranged in a low height strip, approximately 2 cm high, and can emit a pulse in other directions than the slice plane using an acoustical lens in front of rigid flat transducers and time delays.…”

“…Note that the above cited works use transducers positioned around a plane ring. They can improve the results of purely plane slice by slice tomographies accounting for sound scattering from structures out of the transducer plane [29,30]. For a tomograph to be considered truly 3D, it should take into account the waves emitted from a transducer at one height and captured at another.…”