Feature tracking of cine-MRI identifies left ventricular segments with myocardial scar

• Background: The aim of the study was to apply a new feature tracking software (Diogenes MRI, Tomtec GmbH, Unterschliessheim, Germany) on cine-MR images to evaluate its utility and ability to detect infarcted myocardium and to assess the transmural extent of scar without the need for administering intravenous gadolinium-based contrast agents. Methods: Thirty patients (3 women and 27 men) were selected based on the presence or absence of extensive myocardial scar in the perfusion area of the left anterior descending coronary artery (LAD) but not in remote areas. Seventeen had a scar transmurality >75% in at least one segment belonging to the LAD area (scar patients) and thirteen had scar <1% in this area or in other parts of the myocardium (non-scar patients). The software tracked the motion of the wall through the entire cardiac cycle using two different techniques. Velocity, displacement and strain were calculated in 48 points in the longitudinal direction, tangential to the endocardial outline, and in the radial direction, perpendicular to the tangent. Results: In the scar patients, LAD segments showed lower functional measures than remote segments. The remote segments in the scar group showed, in turn, lower functional measures than the remote segments in the non-scar group. Receiver-operatorcharacteristic (ROC) curves were constructed for all measurements. Best area-undercurve was for radial strain, 0.89, where a cut-off value of 38.8% had 80% sensitivity and 86% specificity for the detection of a segment with scar transmurality >50% in the LAD distribution. As a percentage of the mean, intraobserver variability was for radial measures 16-14-26% for displacement-velocity-strain and for the corresponding interobserver measurements 13-12-18%. Conclusions: With the presented method, we show for the first time its ability to detect scar segments with various transmurality already from an analysis of cine-MRI, without the need for the administration of gadolinium-based contrast. The accuracy and repeatability of the radial functional measurements is satisfactory and global measures agree with other aspects of global left ventricular function.

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MEDICIN

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