Combination of contrast-enhanced cardiac MR and nuclear myocardial imaging in evaluation of myocardial viability in ischemic cardiomyopathy

Abstract

Objective To explore the imaging characteristics and the complementarity of contrast- enhanced cardiac magnetic resonance CMR and nuclear myocardial perfusion/metabolic imaging in the evaluation of myocardial viability in patients with ischemic cardiomyopathy. Methods A total of 111 patients with diagnosed coronary artery disease and left ventricular dysfunction were retrospectively enrolled in this study. All patients underwent CMR and nuclear myocardial imaging within 1 month. Cine CMR was employed to evaluate cardiac function and wall motion. Contrast-enhanced CMR and myocardial perfusion/metabolic images were quantitatively assessed using a standard 17-segment and 5-score system. Dysfunctional segments were classified as viable or non- viable based on contrast- enhanced CMR and myocardial perfusion/metabolic imaging, respectively. No enhancement or sub-endocardial enhancement was defined as viable, while transmural enhancement was defined as non-viable. Severely matched perfusion/metabolism defects on nuclear imaging were assigned as non-viable while other patterns were considered as viable.Kappa index was calculated to evaluate the diagnostic concordance in assessing myocardial viability between contrast- enhanced CMR and myocardial perfusion/metabolic imaging. Results Among 1 887 segments in 111 patients, 80.3%(1 516/1 887) were dysfunctional. Of them, 63.3% (959/1 516) were viable and 36.7%(557/1 516) were non-viable on contrast-enhanced CMR, while 79.7%(1 208/1 516) were viable and 20.3% (308/1 516) were non-viable on nuclear myocardial imaging. The two modalities had a moderate concordance (Kappa=0.46, P<0.01). In segments with normal perfusion and metabolism, 73.9% (431/583) had various extent of enhancement but most of them(84.2%, 363/431) were subendocardial. On the other hand, 21.0% (117/557) segments with transmural enhancement had hibernating myocardium on nuclear imaging. Conclusions Contrast-enhanced CMR and nuclear myocardial imaging have a moderate concordance in the evaluation of myocardial viability in ischemic cardiomyopathy. Combination of the two modalities is expected to improve the diagnostic accuracy in assessing myocardial viability. Key words: Myocardium; Magnetic resonance imaging; Nuclear imaging; Myocardial ischemia