A New Technique for the Estimation of Cardiac Motion in Echocardiography Based on Transverse Oscillations: A Preliminary Evaluation In Silico and a Feasibility Demonstration In Vivo

Abstract

Quantification of regional myocardial motion and deformation from cardiac ultrasound is fostering considerable research efforts. Despite the tremendous improvements done in the field, all existing approaches still face a common limitation which is intrinsically connected with the formation of the ultrasound images. Specifically, the reduced lateral resolution and the absence of phase information in the lateral direction highly limit the accuracy in the computation of lateral displacements. In this context, this paper introduces a novel setup for the estimation of cardiac motion with ultrasound. The framework includes an unconventional beamforming technique and a dedicated motion estimation algorithm. The beamformer aims at introducing phase information in the lateral direction by producing transverse oscillations. The estimator directly exploits the phase information in the two directions by decomposing the image into two 2-D single-orthant analytic signals. An in silico evaluation of the proposed framework is presented on five ultra-realistic simulated echocardiographic sequences, where the proposed motion estimator is contrasted against other two phase-based solutions exploiting the presence of transverse oscillations and against block-matching on standard images. An implementation of the new beamforming strategy on a research ultrasound platform is also shown along with a preliminary in vivo evaluation on one healthy subject.

Motion estimation-based image enhancement in ultrasound imaging

“…The size of the simulated US image is 30.04 mm  34.72 mm, or 2311 pixels  217 pixels axially and laterally, respectively. The number of scatterers S, set to 5  10 4 in our experiments, is chosen so that the speckle is fully [23,25].…”

Real‐time ultrasound‐tagging to track the 2D motion of the common carotid artery wall in vivo

“…[35][36][37][38] As for echocardiography, recent studies have presented an extension of the US-tagging framework to assess the 2D motion of the heart wall 39,40 as well as its deformation. 41 Other studies proposed to exploit the monogenic phase of RF-2D images 42,43 and to adapt TOs beamforming to sector scans performed using a phased array 44 as well as a convex array. 45 The application of UStagging to assess LOKI in the CCA has also been investigated by our team in a preliminary one-case study, 46 as well as in combination with ultrafast imaging.…”

The role of the image phase in cardiac strain imaging

“…1(d,f)): the two signal components in (2) capture the orthogonal tag directions, while the frequency f 0 relates to the tag spacing [6]. Finally, a phase definition based on single orthant analytic signals was adopted in [8]. The signal model is:…”

“…Hereto, we analyzed several definitions of image phase in function of their capability to encode relevant image features and to derive accurate motion estimators. They include the monogenic signal [2,5,6], the structure multivector [7] and single-orthant signals [8].…”