T1 Mapping for the Diagnosis of Acute Myocarditis Using CMR Comparison to T2-Weighted and Late Gadolinium Enhanced Imaging

OBJECTIVES This study sought to test the diagnostic performance of native T-1 mapping in acute myocarditis compared with cardiac magnetic resonance (CMR) techniques such as dark-blood T-2-weighted (T2W)-CMR, bright-blood T2W-CMR, and late gadolinium enhancement (LGE) imaging. BACKGROUND The diagnosis of acute myocarditis on CMR often requires multiple techniques, including T2W, early gadolinium enhancement, and LGE imaging. Novel techniques such as T-1 mapping and bright-blood T2W-CMR are also sensitive to changes in free water content. We hypothesized that these techniques can serve as new and potentially superior diagnostic criteria for myocarditis. METHODS We investigated 50 patients with suspected acute myocarditis (age 42 +/- 16 years; 22% women) and 45 controls (age 42 +/- 14 years; 22% women). CMR at 1.5-T (median 3 days from presentation) included: 1) dark-blood T2W-CMR (short-tau inversion recovery); 2) bright-blood T2W-CMR (acquisition for cardiac unified T-2 edema); 3) native T-1 mapping (shortened modified look-locker inversion recovery); and 4) LGE. Image analysis included: 1) global T-2 signal intensity ratio of myocardium compared with skeletal muscle; 2) myocardial T-1 relaxation times; and 3) areas of LGE. RESULTS Compared with controls, patients had significantly higher global T-2 signal intensity ratios by dark-blood T2W-CMR (1.73 +/- 0.27 vs. 1.56 +/- 0.15, p < 0.01), bright-blood T2W-CMR (2.02 +/- 0.33 vs. 1.84 +/- 0.17, p < 0.01), and mean myocardial T-1 (1,010 +/- 65 ms vs. 941 +/- 18 ms, p < 0.01). Receiver-operating characteristic analysis showed clear differences in diagnostic performance. The areas under the curve for each method were: T-1 mapping (0.95), LGE (0.96), dark-blood T-2 (0.78), and bright-blood T-2 (0.76). A T-1 cutoff of 990 ms had a sensitivity, specificity, and diagnostic accuracy of 90%, 91%, and 91%, respectively. CONCLUSIONS Native T-1 mapping as a novel criterion for the detection of acute myocarditis showed excellent and superior diagnostic performance compared with T2W-CMR. It also has a higher sensitivity compared with T2W and LGE techniques, which may be especially useful in detecting subtle focal disease and when gadolinium contrast imaging is not feasible. (C) 2013 by the American College of Cardiology Foundation