A model of distributed phase aberration for deblurring phase estimated from scattering

Abstract

Correction of aberration in ultrasound imaging uses the response of a point reflector or its equivalent to characterize the aberration. Because a point reflector is usually unavailable, its equivalent is obtained using statistical methods, such as processing reflections from multiple focal regions in a random medium. However, the validity of methods that use reflections from multiple points is limited to isoplanatic patches for which the aberration is essentially the same. In this study, aberration is modeled by an offset phase screen to relax the isoplanatic restriction. Methods are developed to determine the depth and phase of the screen and to use the model for compensation of aberration as the beam is steered. Use of the model to enhance the performance of the noted statistical estimation procedure is also described. Experimental results obtained with tissue-mimicking phantoms that implement different models and produce different amounts of aberration are presented to show the efficacy of these methods. The improvement in b-scan resolution realized with the model is illustrated. The results show that the isoplanatic patch assumption for estimation of aberration can be relaxed and that propagation-path characteristics and aberration estimation are closely related.

The Impact of Model-Based Clutter Suppression on Cluttered, Aberrated Wavefronts

“…The resulting degradation is primarily thought to be arrival time variation called phase aberration. In order to minimize the effects of phase aberration, many methods have been developed to correct distorted wavefronts [4], [7]–[14]. …”

3-D Transcranial Ultrasound Imaging with Bilateral Phase Aberration Correction of Multiple Isoplanatic Patches: A Pilot Human Study with Microbubble Contrast Enhancement

“…3). This technique builds on the investigations of Waag and colleagues into propagation path-dependence of aberration, in which measurements made using multiple sets of transmit-receive aperture pairs are used to correct for path-dependent effects which cause the nearfield phase screen model to break down (Waag and Astheimer 2005; Astheimer et al 2006; Tillett et al 2010). …”

Comparison of temporal and spectral scattering methods using acoustically large breast models derived from magnetic resonance images

“…Versions of the aberration correction algorithms have been verified in experiments to produce essentially diffractionlimited focusing. 5,6 Quantification of resolution limits in the presence of aberration and with the use of aberration correction will lead to development of improved focusing techniques. These techniques could also be used to tailor transducer apertures to obtain the best balance between resolution and cost for commercial systems that image in vivo human tissues, resulting in improved diagnostic capabilities.…”