Quantitative cardiac magnetic resonance standardized signal intensity comparison in dilated cardiomyopathy vs. cardiac sarcoidosis.

Background: Dilated cardiomyopathy (DCM) and cardiac sarcoidosis (CS) manifest unique late gadolinium enhancement (LGE) patterns on cardiac magnetic resonance (CMR), indicative of different myocardial scar distributions. However, the overlap in these patterns due to their lack of specificity complicates differentiation. This study introduces a novel quantitative method employing z-score analysis of LGE-CMR intensity to objectively compare the spatial distribution of LGE intensity between DCM and CS.

Methods: This retrospective study included 22 NICM patients (13 DCM, 9 CS) who underwent CMR before electrophysiology study from November 2018 to May 2023. LGE images were delineated into sub-endocardial, mid-myocardial, and sub-epicardial layers across anterior, lateral, inferior, and septal walls using the AHA 17-segment model. CMR signal intensities were standardized to z-scores (z = (x - μ)/σ), with x as the signal intensity for a specific myocardial segment, and μ and σ as the mean and SD for all LV myocardial segments, to map regional intensity variations.

Results: Compared to DCM, CS patients exhibited significantly higher CMR signal intensity z-scores in the septum (β = 0.32, p = 0.009), particularly in the endocardial third of the right ventricular (RV) side (β = 0.56, p = 0.001). A z-score greater than 0.40 in this area was associated with a CS diagnosis, with an area under the ROC curve of 0.692 in fivefold cross-validation.

Conclusion: Patients with CS exhibit higher affinity for contrast in the septum, particularly on the RV endocardium. Standardized analysis of CMR signal intensities provides a novel, quantitative method for distinguishing CS from DCM, with the former exhibiting higher CMR signal intensity z-scores in the septum.