Regional cardiac motion and strain estimation in three-dimensional echocardiography: a validation study in thick-walled univentricular phantoms

Abstract

Automatic quantification of regional left ventricular deformation in volumetric ultrasound data remains challenging. Many methods have been proposed to extract myocardial motion, including techniques using block matching, phase-based correlation, differential optical flow methods, and image registration. Our lab previously presented an approach based on elastic registration of subsequent volumes using a B-spline representation of the underlying transformation field. Encouraging results were obtained for the assessment of global left ventricular function, but a thorough validation on a regional level was still lacking. For this purpose, univentricular thick-walled cardiac phantoms were deformed in an experimental setup to locally assess strain accuracy against sonomicrometry as a reference method and to assess whether regions containing stiff inclusions could be detected. Our method showed good correlations against sonomicrometry: r(2) was 0.96, 0.92, and 0.84 for the radial (ε(RR)), longitudinal (ε(LL)), and circumferential (ε(CC)) strain, respectively. Absolute strain errors and strain drift were low for ε(LL) (absolute mean error: 2.42%, drift: -1.05%) and ε(CC) (error: 1.79%, drift: -1.33%) and slightly higher for ε(RR) (error: 3.37%, drift: 3.05%). The discriminative power of our methodology was adequate to resolve full transmural inclusions down to 17 mm in diameter, although the inclusion-to-surrounding tissue stiffness ratio was required to be at least 5:2 (absolute difference of 39.42 kPa). When the inclusion-to-surrounding tissue stiffness ratio was lowered to approximately 2:1 (absolute difference of 22.63 kPa), only larger inclusions down to 27 mm in diameter could still be identified. Radial strain was found not to be reliable in identifying dysfunctional regions.

3D Strain Assessment in Ultrasound (Straus): A Synthetic Comparison of Five Tracking Methodologies

“…Polyvinyl alcohol (PVA) gels [20] have been proposed as a tissue-mimicking material for MR and US. Since the number of freeze-thaw cycles affects the properties of the material, stiffer inclusions can be embedded for quantifying the localizability of lesions, both in terms of size and stiffness extent [21].…”

Patient-Specific Quantitation of Mitral Valve Strain by Computer Analysis of Three-Dimensional Echocardiography

“…Automated registration of 3D echocardiographic image sequences is crucial to quantify cardiac deformations 15,17 and to compute mitral leaflets strain. MV apparatus deformations were modeled by diffeomorphisms of R 3 , [18][19][20][21] which are arbitrary invertible and continuously differentiable 3D spatial deformations.…”

Three-Dimensional Cardiac Motion Estimation Based on Non-rigid Image Registration Using a Novel Transformation Model Adapted to the Heart

“…The choice of these registration components have all been proven useful for myocardial motion estimation [1,2,3]. In practice, subsequent images I f were registered to each other in a pair-wise fashion.…”

“…Traditionally, this FFD model is formulated in Cartesian space (Fig. 1a), and has already been shown to be successful for cardiac motion estimation of ultrasound data [1,2,3]. However, this topology may be suboptimal as it treats the blood pool and the myocardium similarly, and as it intrinsically imposes spatial smoothness in non-physiologic directions.…”