|In the setting of clinically suspected myocarditis,*CMR findings are consistent with myocardial inflammation, if at least 2 of the following criteria are present:|
|Regional or global myocardial SI increase in T2-weighted images.†|
|Increased global myocardial early gadolinium enhancement ratio between myocardium and skeletal muscle in gadolinium-enhanced T1-weighted images.‡|
|There is at least 1 focal lesion with nonischemic regional distribution in inversion recovery-prepared gadolinium-enhanced T1-weighted images (“late gadolinium enhancement”).§|
|A CMR study is consistent with myocyte injury and/or scar caused by myocardial inflammation if Criterion 3 is present.|
|A repeat CMR study between 1 and 2 weeks after the initial CMR study is recommended if|
|None of the criteria are present, but the onset of symptoms has been very recent and there is strong clinical evidence for myocardial inflammation.|
|One of the criteria is present.|
|The presence of LV dysfunction or pericardial effusion provides additional, supportive evidence for myocarditis.|
Abbreviations as in Table 6.
↵* The clinical suspicion for active myocarditis should be based on the criteria listed in Table 5.
↵† Images should be obtained using a body coil or a surface coil with an effective surface coil intensity correction algorithm; global signal intensity (SI) increase has to be quantified by an SI ratio of myocardium over skeletal muscle of ≥2.0). If the edema is more subendocardial or transmural in combination with a colocalized ischemic (including the subendocardial layer) pattern of late gadolinium enhancement, acute myocardial infarction is more likely and should be reported.
↵‡ Images should be obtained using a body coil or a surface coil with an effective surface coil intensity correction algorithm; a global SI enhancement ratio of myocardium over skeletal muscle of ≥4.0 or an absolute myocardial enhancement of ≥45% is consistent with myocarditis.
↵§ Images should be obtained at least 5 min after gadolinium injection; foci typically exclude the subendocardial layer, are often multifocal, and involve the subepicardium. If the late gadolinium enhancement pattern clearly indicates myocardial infarction and is colocalized with a transmural regional edema, acute myocardial infarction is more likely and should be reported.