Diagnosis of acute global myocarditis using cardiac MRI with quantitative t1 and t2 mapping: case report and literature review

Abstract

The diagnosis of myocarditis can be challenging given that symptoms, clinical exam findings, electrocardiogram results, biomarkers, and echocardiogram results are often non-specific. Endocardial biopsy is an established method for diagnosing myocarditis, but carries the risk of complications and false negative results. Cardiac magnetic resonance imaging (MRI) has become the primary non-invasive imaging tool in patients with suspected myocarditis. Myocarditis can be diagnosed by using three tissue markers including edema, hyperemia/capillary leak, and necrosis/fibrosis. The interpretation of cardiac MR findings can be confusing, especially when the myocardium is diffusely involved. Using T1 and T2 maps, the diagnosis of myocarditis can be made even in cases of global myocarditis with the help of quantitative analysis. We herein describe a case of acute global myocarditis which was diagnosed by using quantitative T1 and T2 mapping.

Keywords: Magnetic resonance imaging; Myocarditis; T1 map; T2 map.

Fig. 1

Cardiac MR findings in acute global myocarditis. Cine images during end-diastolic (A) and end-systolic (B) phases demonstrated global systolic dysfunction with EF of 30%. T2-Weighted images (C) revealed global edema with ratio of myocardium to skeletal muscle of > 2.0. On TI scout images, it was difficult to determine optimal nulling time for LV. We selected 270 ms as ideal nulling time in this study (D). LV = left ventricle, SI = signal intensity, EF = ejection fraction. On LGE images with magnitude and PSIR (E, F), diffuse hyper SI of entire LV myocardium was likely but uncertain. T2 map images (G) and Pre-T1 map images (H) demonstrated diffuse myocardial edema with increased T2 and T1 values. LGE = late gadolinium enhancement, LV = left ventricle, PSIR = phase-sensitive inversion recovery. On post-T1 mapping images (I), mean myocardial T1 value was similar to T1 value for LV cavity. Mean ECV fraction of LV myocardium was 45.9 ± 1.9% (range: 43-49.7%). ECV = extracellular volume, LV = left ventricle