Contrast-enhanced myocardial inversion time at the null point for detection of left ventricular myocardial fibrosis in patients with dilated and hypertrophic cardiomyopathy: A Pilot Study

Abstract

OBJECTIVE. The purpose of this article is to investigate a noninvasive method for quantifying diffuse myocardial fibrosis with cardiac MRI in patients with dilated cardiomyopathy and hypertrophic cardiomyopathy. MATERIALS AND METHODS. We performed cardiac MRI on 35 patients (24 patients with dilated cardiomyopathy and 11 patients with hypertrophic cardiomyopathy) and 10 control subjects, on a clinical 1.5-T cardiac MRI scanner. Delayed hyperenhancement images were obtained 15 minutes after injection of a bolus of gadopentetate dimeglumine (0.2 mmol/kg), to identify fibrosis using an inversion recovery gradient-echo technique (inversion time scout sequence: TR, 20.8 milliseconds; TE, 1.3 milliseconds; inversion time, individually determined to null the myocardial signal [range, 85-800 milliseconds]). An inversion time mapping sequence was used to calculate the contrast-enhanced myocardial inversion time at the null point of a single midventricular slice as an index of diffuse fibrosis. RESULTS. The mean contrast-enhanced myocardial inversion time at the null point was significantly shorter in the patient group than the control group (343. 7 ± 27.9 vs 390.4 ± 19.3 milliseconds; p < 0.0001). In the patient group, the mean contrast-enhanced myocardial inversion time at the null point was shorter in patients with dilated cardiomyopathy than in patients with hypertrophic cardiomyopathy (337.0 ± 29.6 vs 358.6 ± 17.1 milliseconds, p = 0.02). In the dilated cardiomyopathy group, contrast-enhanced myocardial inversion time at the null point was significantly related to the left ventricular ejection fraction (r = 0.52; p = 0.01). However, in the hypertrophic cardiomyopathy group, contrast-enhanced myocardial inversion time at the null point had only a small positive correlation with the left ventricular ejection fraction (r = 0.27; p = 0.41). CONCLUSION. Contrast-enhanced myocardial inversion time at the null point is shorter with myocardial fibrosis in patients with dilated cardiomyopathy and hypertrophic cardiomyopathy. In dilated cardiomyopathy, contrast-enhanced myocardial inversion time at the null point is inversely related to the severity of dilated cardiomyopathy Copyright © 2010 by the American Roentgen Ray Society.