Regional myocardial contractile function: multiparametric strain mapping.

Magnetic resonance imaging (MRI) with tissue tagging enables the quantification of multiple strain indices that can be combined through normalization into a single multiparametric index of regional myocardial contractile function. The aim of this study was to test the ability of multiparametric strain analysis to quantify regional differences in contractile function in an ovine model of myocardial injury. Regional variance in myocardial contractile function was induced in eight sheep by the ligation of the blood supply to the anterior and apical left ventricular (LV) myocardial walls. LV systolic strain was obtained from tissue tagged MRI images. A normal strain database (n=50) defines all parameters of systolic strain and allows normalization of regional function at 15,300 LV points by calculation of a z-score. Multiparametric systolic strain z-scores were therefore determined for 15,300 points in each injured sheep left ventricle. Multiparametric z-scores were found to vary significantly by region (P<0.001). z-Scores in regions remote to the infarct were found to be significantly smaller than those in the regions most likely to include infarcted myocardium. In this pre-clinical evaluation of MRI-based multiparametric strain analysis, it accurately quantified and visually defined regional differences in myocardial contractile function.