MR Imaging of Arrhythmogenic Right Ventricular Cardiomyopathy: Morphologic Findings and Interobserver Reliability

Abstract

Background: Magnetic resonance (MR) imaging is frequently used to diagnose arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). However, the reliability of various MR imaging features for diagnosing ARVC/D is unknown. The purpose of this study was to determine which morphologic MR imaging features have the greatest interobserver reliability for diagnosing ARVC/D. Methods: Forty-five sets of films of cardiac MR images were sent to 8 radiologists and 5 cardiologists with experience in this field. There were 7 cases of definite ARVC/D as defined by the Task Force criteria. Six cases were controls. The remaining 32 cases had MR imaging because of clinical suspicion of ARVC/D. Readers evaluated the images for the presence of (a) right ventricle (RV) enlargement, (b) RV abnormal morphology, (c) left ventricle enlargement, (d) presence of high T₁ signal (fat) in the myocardium, and (e) location of high T₁ signal (fat) on a Likert scale with formatted responses. Results: Readers indicated that the Task Force ARVC/D cases had significantly more (χ² = 119.93, d.f. = 10, p < 0.0001) RV chamber size enlargement (58%) than either the suspected ARVC/D (12%) or no ARVC/D (14%) cases. When readers reported the RV chamber size as enlarged they were significantly more likely to report the case as ARVC/D present (χ²⁼33.98, d.f. = 1, p < 0.0001). When readers reported the morphology as abnormal they were more likely to diagnose the case as ARVC/D present (χ² = 78.4, d.f. = 1, p < 0.0001), and the Task Force ARVC/D (47%) cases received significantly more abnormal reports than either suspected ARVC/D (20%) or non-ARVC/D (15%) cases. There was no significant difference between patient groups in the reported presence of high signal intensity (fat) in the RV (χ² = 0.9, d.f. = 2, p > 0.05). Conclusions: Reviewers found that the size and shape of abnormalities in the RV are key MR imaging discriminates of ARVD. Subsequent protocol development and multicenter trials need to address these parameters. Essential steps in improving accuracy and reducing variability include a standardized acquisition protocol and standardized analysis with dynamic cine review of regional RV function and quantification of RV and left ventricle volumes.

Arrhythmogenic right ventricular cardiomyopathy/dysplasia: a not so rare “disease of the desmosome” with multiple clinical presentations

“…Quantitative analysis showed that RV enddiastolic diameter and outflow tract area were significantly higher, and RV ejection fraction lower in ARVC/D patients compared to controls 66 . Using less dedicated software, the presence of fatty infiltration of the right ventricular myocardium may be less reliably detected 68 . Moreover, even in normal individuals epicardial fat is usually present and tongues of epicardial fat may extend into the RV myocardium 68 .…”

“…Using less dedicated software, the presence of fatty infiltration of the right ventricular myocardium may be less reliably detected 68 . Moreover, even in normal individuals epicardial fat is usually present and tongues of epicardial fat may extend into the RV myocardium 68 . ARVC/D patients, but not normal individuals, have fibrosis of the RV as well as fatty infiltrates, which both may be detected by MRI 69 .…”

Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

“…MRI is emerging as a useful "Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia" non-invasive tool to identify morphologic abnormalities such as myocardial fat, right ventricular chamber size and shape, and wall motion abnormalities with newer cine techniques. However, with conventional MR technology, the identification of myocardial fat was not found to be a reliable predictor of the presence of ARVC/D 15 . Diffuse hypokinesis or regional wall motion abnormalities of the right ventricle can be seen with contrast ventriculography, considered to be the most reliable test to assess structural abnormalities.…”

Arrhythmogenic Cardiomyopathy: Electrical and Structural Phenotypes

“…120 Yet, myocardial fibrosis and fat as potential diagnostic features were not integrated in the TFC, because of their limited specificity, high intra-and inter-observer variability and the need for highly specialised interpreters. 121,122 This owes to the fact that the RV is very thin and epicardial fat cannot reliably be distinguished from intramyocardial fat. However, CMR plays an important role for ARVC/D diagnosis (see Figure 2A).…”