Clinical and Advanced MRI Techniques for Detection of Checkpoint Inhibitor Associated Myocarditis

Purpose of Review With the advent of immune checkpoint inhibitors (ICIs), cancer treatment has been revolutionized; however, these agents are associated with immune-related adverse events, including myocarditis, which ranges from mild to fulminant in severity. Currently, there are no established guidelines in diagnosing ICI-associated myocarditis, and the gold standard test for diagnosis of myocarditis in general is invasive endomyocardial biopsy (EMB). Cardiac magnetic resonance (CMR) imaging is a noninvasive test with the advantage of providing structural, functional and tissue characterization information. Additionally, it provides high spatial and temporal resolution without exposure to ionizing radiation, iodinated contrast, or radioactive isotopes. Recent Findings With an increasing number of reported cases of ICI associated myocarditis, understanding of the disease process and associated CMR findings is growing. Diagnostic testing with cardiac biomarkers, electrocardiogram, and echocardiogram can be nonspecific and EMB can have sampling errors. CMR as a diagnostic tool can provide functional assessment of biventricular ejection fraction, myocardial strain, tissue characterization of myocardial edema and inflammation as well as fibrosis. Furthermore, with advanced parametric mapping techniques, CMR provides even more sensitive and quantitative information about myocardial inflammation and fibrosis, including measurements of extracellular volume. Summary ICI-associated myocarditis is a serious immune adverse event, and CMR plays a vital role in establishing its diagnosis, providing prognostic information, and has the potential for use as a tool for screening and serial monitoring in patients exposed to ICIs.