SURF imaging beams in an aberrative medium: generation and postprocessing enhancement

TL;DR

This study demonstrates that SURF imaging beams can be generated and enhanced through postprocessing even in strongly aberrative media, such as body-walls, which distort ultrasound wave-fronts and affect reverberation suppression.

Contribution

It shows the feasibility of generating and postprocessing SURF imaging beams in aberrative media, extending previous homogeneous medium studies to more realistic scenarios.

Findings

Synthetic SURF beams are achievable in aberrative conditions.

Postprocessing methods effectively adjust reverberation suppression depth.

Aberrations larger than previously measured still allow SURF techniques to work.

Abstract

This paper presents numerical simulations of dual-frequency second-order ultrasound field (SURF) reverberation suppression transmit-pulse complexes. Such propagation was previously studied in a homogeneous medium. Here instead the propagation path includes a strongly aberrating body-wall modeled by a sequence of delay-screens. The applied SURF transmit pulse complexes each consist of a high-frequency imaging 3.5 MHz pulse combined with a low-frequency 0.5 MHz sound speed manipulation pulse. Furthermore, the feasibility of two signal post-processing methods are investigated using the aberrated transmit SURF beams. These methods are previously shown to adjust the depth of maximum SURF reverberation suppression within a homogeneous medium. The request of the study arises because imaging situations where reverberation suppression is useful are also likely to produce pulse wave-front distortion (aberration). Such distortions could potentially produce time-delays that cancel the accumulated propagation time-delay needed for the SURF reverberation suppression technique. Results show that both the generation of synthetic SURF reverberation suppression imaging transmit-beams, and the following post-processing adjustments, are attainable even when a body-wall introduces time-delays which are larger than previously reported delays measured on human body-wall specimens. The peer-reviewed version of this paper is published in IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, vol. 59, no. 11, pp. 2588-2595, November 2012. DOI: 10.1109/TUFFC.2012.2494 The final version is available online at http://dx.doi.org/10.1109/TUFFC.2012.2494 The current e-print is typeset by the authors and differs in e.g. pagination and typographic detail.