Quantitative Assessment of the Effect of the Out-of-Plane Movement of the Homogenous Ellipsoidal Model of the Left Ventricle on the Deformation Measures Estimated Using 2-D Speckle Tracking—An In-Silico Study

Abstract

Effect of the out-of-plane (OOP) movement amplitude on estimates of global displacements (radial, circumferential) and strains (radial , circumferential ) was studied in an ellipsoidal model of the left ventricle using finite-element modeling (FEM), synthetic ultrasonic data, and short-axis view. This effect was assessed using median of the absolute relative error (RE) of the global parameters. FEM provided node displacements for synthetic ultrasonic data and reference data generation. Displacements were estimated using block-matching (BM) and B-spline (BS) methods. FEM-derived data analysis, free from errors resulting from speckle tracking, indicated that the tissue motion introduced REs of global strain estimates below 4.5%. The effect of the OOP motion amplitude on strain estimates was strain specific and depended on the displacement estimation method. In the case of , the increase of the OOP amplitude resulted in quasi-linear increase of the RE from approximately 10% to 15%. The modulus of the end-systolic (ES) errors of the estimates almost linearly increased with increasing OOP amplitude approximately from 10% to 16%. REs of the estimate were close to 80% and 40%, respectively, in the case of the BM and BS methods, and increased with increasing OOP amplitude. The modulus of the ES errors of the estimates in the case of the BS method was about -40% and showed low sensitivity to the OOP amplitude; in the BM case, these errors varied approximately from -70% to -58% for OOP amplitude from 0 to 15 mm.

Evaluation of strain averaging area and strain estimation errors in a spheroidal left ventricular model using synthetic image data and speckle tracking

“…The LV model exploited in this study was based on a physical LV phantom [ 30 ], similarly as presented previously [ 2 , 7 , 31 , 32 ]. Modeling technique and all the properties of the model resulting from extensive studies were described in [ 33 ].…”

“…Synthetic RF data were generated analogically as in [ 7 ]. Briefly, the RF data were simulated using FIELD II package [ 50 , 51 ] and meshes obtained from the FEM simulations.…”

“…Incremental (interframe) displacements were estimated using a hierarchical block matching method (HBM) [ 52 ] in implementation similar to that described in [ 11 ], expanded by two-directional incremental displacement estimation [ 2 , 7 , 32 ]. The main algorithm is shown in the Fig.…”

“…It is of interest to address the resolution of the STE together with accuracy of the strain estimation, as both are important from the clinical point of view. There were numerous studies on the STE accuracy [ 7 – 20 ], however, comparison of their results is difficult, due to different study design or different error measures used. One of the conclusions of these works is that the accuracy of global strain estimates is of order of several hundredths and that of global displacement estimates is about 1–2 mm.…”

“…One of the conclusions of these works is that the accuracy of global strain estimates is of order of several hundredths and that of global displacement estimates is about 1–2 mm. Some results indicate a link between estimation accuracy and the direction of the displacement with respect to the ultrasonic wave propagation direction [ 2 , 7 , 11 , 14 , 20 ]. The errors of the estimate of the deformation perpendicular to the wave propagation direction are usually greater than those of the deformation parallel to this direction.…”