Acute myocarditis is an inflammation of the heart muscle commonly of viral etiology.

Diagnostic cardiac MRI (CMR) criteria are based on the demonstration of edema, hyperemia, and necrosis in the myocardium (Lake Louise criteria). 

The typical late gadolinium enhancement (LGE) pattern is subepicardial and mid myocardial involving the lateral wall of the left ventricle and the interventricular septum.