Experimental setup with dual chamber cardiac phantom for ultrasonic elastography

Abstract

Strain (S) and strain rate (SR) imaging may enable to detect and quantify changes in regional myocardial wall contractility and viability. However, the range and rate of cardiac wall deformation make development and evaluation of strain estimation algorithms difficult. A well-controlled experimental setup capable of producing the deformation patterns similar to those encountered in vivo may provide controlled data for this development. Such a setup was build, consisting of a 2-chamber biventricular homogeneous Polyvinyl Alcohol (PVA) heart phantom connected to a hydraulic pulsatile mock circulation system. The phantom was cyclically deformed using a computer controlled piston pump at a stroke volume near 83 ml, stroke rate of 1 Hz, and systole/diastole ratio 2/3. The internal LV pressure data were collected using a tip-catheter manometer (F 4.1, Sentron, Nl). Two dimensional color Doppler myocardial imaging (CDMI) data were recorded from the phantom using standard long and short axis views (∼200 frames/s, 2.4 MHz, Vivid 7, GE, Norway). Tissue velocity (TV), S and SR values for both radial and longitudinal phantom wall deformation were estimated. For radial deformation SR and S profiles were computed for anterior, lateral, posterior and inferior LV wall segments. For longitudinal deformation, they were determined for mid segment of the lateral LV wall. The obtained values of TV, SE and S are close to those found in clinical research. The experimental setup appears to be an interesting tool providing controlled data for testing new methods and algorithms for myocardial strain and strain rate estimation.