Detection and Quantification of Myocardial Scars using Contrast-Enhanced 3D-Echocardiography Running Title: Infarct size by 3D-Echo

Background Myocardial infarct scars are usually imaged using delayed-enhanced cardiac magnetic resonance (DE-cMR). In this study, we tested the hypothesis that the detection and the quantification of myocardial scars can be evaluated by 3D-Echo. Methods and Results Fifty patients with a healed myocardial infarction (>3 months) and 10 controls underwent 3D-Echo and DE-cMR within 2 weeks. 3D-Echo images were acquired using different settings, in the presence or absence of contrast. The highest contrast-to-noise ratio was obtained using second harmonic imaging (1.6/3.2 MHz), at an MI of 0.5, in the presence of contrast. Using this modality, the sensitivity and specificity for the 3D-Echo detection of cMR scars on a segmental basis were 78% and 99%, respectively. On a per patient basis, they were of 96% and 90%, respectively. Good correlation and limits of agreement were found between the assessment of scar mass by 3D-Echo and DE-cMR (r=0.93, p<0.001, bias: 1.4±3.6g), and the concordance between both techniques for the assessment of scar transmurality was good. Intraobserver, interobserver and day-to-day reproducibility was comparable between 3D-Echo and DE-cMR for both the detection and the quantification of scars. Conclusions Contrast-enhanced 3D-Echo is a promising new tool for the detection and the quantification of myocardial infarct scars.