Accuracy of cardiovascular magnetic resonance in myocarditis: comparison of MR and histological findings in an animal model

Abstract

Background: Because endomyocardial biopsy has low sensitivity of about 20%, it can be performed near to myocardium that presented as late gadolinium enhancement (LGE) in cardiovascular magnetic resonance (CMR). However the important issue of comparing topography of CMR and histological findings has not yet been investigated. Thus the current study was performed using an animal model of myocarditis.

Results: In 10 male Lewis rats experimental autoimmune myocarditis was induced, 10 rats served as control. On day 21 animals were examined by CMR to compare topographic distribution of LGE to histological inflammation. Sensitivity, specificity, positive and negative predictive values for LGE in diagnosing myocarditis were determined for each segment of myocardium. Latter diagnostic values varied widely depending on topographic distribution of LGE and inflammation as well as on the used CMR sequence. Sensitivity of LGE was up to 76% (left lateral myocardium) and positive predictive values were up to 85% (left lateral myocardium), whereas sensitivity and positive predictive value dropped to 0-33% (left inferior myocardium).

Conclusions: Topographic distribution of LGE and histological inflammation seem to influence sensitivity, specificity, positive and negative predictive values. Nevertheless, positive predictive value for LGE of up to 85% indicates that endomyocardial biopsy should be performed "MR-guided". LGE seems to have greater sensitivity than endomyocardial biopsy for the diagnosis of myocarditis.

Figure 1

Distribution of histological inflammation. Bullseye plots showing distribution of histologically verified inflammation inside right (A) and left (B) ventricular wall from apex (internal segment) to heart base (external segments). Myocardial inflammation was predominantly located in the anterior and lateral wall of right and left ventricle.

Figure 2

Distribution of Late Gadolinium Enhancement. Bullseye plots showing distribution of LGE (LGE) inside the left ventricular wall from apex (internal segments) to heart base (external segments). LGE was mainly located in the anterior and lateral wall of the left ventricle.

Figure 3

Sample images of CMR. CMR images and histopathological finding of an animal from the experimental group: (A) Turbo-FLASH-examination without fat saturation. (B) TSE-examination without fat saturation. (C) Histopathological findings with visible infiltration in the left anterior.