Suspected Chronic Myocarditis at Cardiac MR: Diagnostic Accuracy and Association with Immunohistologically Detected Inflammation and Viral Persistence

Abstract

In patients clinically suspected of having CMC, increased gRE and ER indicating inflammation were common findings that could be confirmed at immunohistologic analysis, whereas LE had low sensitivity and accuracy. Cardiac MR imaging may be helpful in detecting intramyocardial inflammation noninvasively, but it fails to depict viral persistence.

The emerging clinical role of cardiovascular magnetic resonance imaging

“…It was shown that early enhancement changes are detectable soon after the clinical onset of disease and vanish with declining symptoms at follow-up (121). Two studies from independent working groups have shown that sequences that assess edema and hyperemia are more sensitive, while late enhancement imaging is more specific for the diagnosis of myocarditis (117,118). This is in accordance with the current understanding of pathophysiology.…”

“…• T1-weighted early contrast-enhanced sequences assess myocardial hyperemia and capillary leak (116); • T2-weighted sequences assess myocardial edema (117,118); and • Late enhancement assesses cardiomyocyte necrosis or fibrosis (119,120). Therefore, a comprehensive in vivo assessment of tissue pathology is possible, beyond the analysis of myocardial volumes and function.…”

“…This combined approach yielded a sensitivity of 76%, a specificity of 95.5% and an accuracy of 85% for the diagnosis of acute myocarditis in a study applying comprehensive clinical information as a reference standard (117). Another study of patients with chronic active myocarditis, using myocardial biopsy with histology and immunohistology as a reference standard, yielded a sensitivity of 62%, a specificity of 89% and a diagnostic accuracy of 74% (118). In a recent review paper (123), CMR imaging was considered to be the most powerful noninvasive tool for determining whether active myocarditis is present.…”

Myocarditis-A Quick Review

“…For example, regions of myocarditis are reported to correlate closely with regions of abnormal signal on cardiac MRI. 7,8 The lack of consensus regarding the value of invasive studies such as endomyocardial biopsy and the overall good prognosis for patients with mild, acute dilated cardiomyopathy who have suspected myocarditis have led to recent recommendations that endomyocardial biopsy should be considered on the basis of the likelihood of finding specific treatable disorders. …”

Modern Imaging of Myocarditis: Possibilities and Challenges

“…2): 1) a regional or global myocardial signal intensity (SI) increase on T2-weighted (T2w) images, 2) an increased global myocardial early gadolinium enhancement ratio (EGEr) between myocardium and skeletal muscle in gadolinium-enhanced T1-weighted (T1w) images, and 3) at least one focal lesion with non-ischemic regional distribution in inversion recovery-prepared gadolinium-enhanced T1w images (late gadolinium enhancement, LGE). The SI increase on T2w images can either be analyzed visually or can be quantified by an SI ratio of myocardium over skeletal muscle of ≥ 1.9 ("T2-ratio" / "edema ratio") [22,23]. The largest to date meta-analysis dealing with the T2-ratio showed an average sensitivity of 70 % and an average specificity of 71 % for detecting myocardial edema [21].…”