How to Image Myocarditis

Myocarditis is an inflammatory disease involving the heart muscle and potentially the pericardium. While there are many potential causative agents, commonly grouped into infectious (viral, bacterial, parasitic) or noninfectious (autoimmune, systemic disorders, drugs, cancer related), the main pathological pathways ultimately lead to an inflammatory process of the myocardium resulting in necrosis and edema. As there are specific therapies available for patients with myocarditis, reliable and early diagnosis is crucial. Multimodality imaging, especially cardiovascular magnetic resonance, has made a noninvasive diagnosis feasible. Cardiovascular magnetic resonance can not only provide a diagnosis based on the updated Lake Louise criteria, but it also functions as a diagnostic gateway, leading to other imaging modalities, for example, positron emission tomography or computed tomography. Finally, imaging results can help to initiate treatment options as well as determine when a patient can return to work or exercise. This review will cover multimodal imaging in patients with myocarditis with a focus on cardiovascular magnetic resonance, providing case examples of how imaging can guide care and treatment in these patients. In addition, the review focuses on the recent European Society for Cardiology guideline on the management of myocarditis and pericarditis comparing the recommendation to the American College of Cardiology expert consensus statements and the Japanese Circulation Society guidelines.