Semiquantitative Analysis of Ischemic Dysfunctional Myocardial Tissue: Comparison of Contrast Enhanced MRI and Myocardial PET

Cardiac Positron Emission Tomography (PET) has been demonstrated to be highly specific in differentiating viable from scarred myocardium in patients with ischemic left ventricular dysfunction. The aim of this study was to compare PET imaging with contrast-enhanced magnetic resonance imaging (ceMRI) in patients with ischemic myocardial dysfunction, analysing semiquantitatively the amount of non-viable myocardial tissue. Results: 10 patients with left ventricle ischemic dysfunction underwent myocardial PET with 13N-ammonia/FDG and delayed sequences of cardiac MRI after injection of gadolinium diethyltriaminepentaacetic acid (Gd-DTPA). PET and MRI images were divided into 17 segments and examined by 2 independent observers. Extent of tissue damage was estimated using a 5- point scoring system. Using PET as gold standard, accuracy in detecting scar tissue was determined for ceMRI. High agreement rate (63% and 69%) between myocardial necrosis in PET and ceMRI was evaluated by Kappa test. Comparison between scores in transmutable extension in PET/ceMRI study with a “0 tolerance” system (that is considering results agreement only if overlap results), the 2 blinded observers demonstrated an agreement rate of 68.9% and 76.5% respectively, with a difference of 7.6% [IC 95% from – 2 to 17.1]. With one point of tolerance (considering results agreement even if there was one point of difference), an agreement rate of 93.6 and 95.3% emerged, with a difference of 1.8% [IC 95% from -3.1 to 6.6%]. Conclusions: In the identification of non-viable myocardium, semiquantative analysis of cardiac PET and ceMRI obtained similar accuracy of the two imaging techniques.