Association of segmental T2 ratio and late gadolinium enhancement in patients with acute myocarditis: a feasibility study

Background: Cardiac Magnetic Resonance is a valuable tool in the diagnosis of acute myocarditis, but dyspnea or chest pain often reduce patient's compliance, so definition of faster MR protocols is of paramount importance. Methods: Short Tau Inversion Recovery(STIR) and Phase Sensitive Inversion Recovery(PSIR)images for the assessment of Late Gadolinium Enhancement(LGE)of 22 patients with clinical suspicion of acute myocarditis were retrospectively evaluated. Signal intensity in STIR images was measured by 2 readers by placing region of interests(ROIs)within the area of maximal signal intensity in each myocardial segment derived from the ACC/AHA segmental scheme. Segmental T2 ratio was assessed with the formula: Signal intensity of myocardium/Signal intensity of muscle. Receiver operating characteristic (ROC) curves were used to compare diagnostic performance of T2 Signal intensity and T2 ratio in predicting the presence of LGE in each myocardial segment. Bland-Altman analysis was used to assess inter reader agreement. Results: Signal intensity in STIR images showed an AUC of 0.54(95%CI:0.44-0.63) for Reader 1 and 0.53(95%CI:0.44-0.63) for Reader 2. Segmental T2 ratio showed an AUC of 0.8(95%CI:0.73-0.87) for Reader 1 and 0.77(95%CI:0.71-0.84) for Reader 2. Bland-Altman analysis showed good agreement for both T2 signal intensity(mean difference =-18.5 Reader1 Vs Reader 2 and 2SD=247.3)and T2 ratio(mean difference=0.03 Vs Reader2 and 2SD=0.9). Conclusions: Segmental T2 ratio showed a good diagnostic accuracy in predicting the presence of LGE in patients with clinical suspicion of acute myocarditis and might be a promising approach in reducing scan times with no reduction in diagnostic accuracy