Abstract Body (Do not enter title and authors here): Introduction/Background: Dilated cardiomyopathy (DCM) and cardiac sarcoidosis (CS) manifest unique late gadolinium enhancement (LGE) patterns on cardiac magnetic resonance (CMR), indicative of differing distributions of myocardial scar tissue. Nevertheless, these LGE patterns lack specificity, leading to significant overlap between the two conditions.

Goals/Aims: This study seeks to introduce a novel quantitative method employing z-score analysis of LGE-CMR signal intensity to objectively evaluate and compare the spatial distribution of LGE intensity between DCM and CS.

Methods/Approach: The retrospective cohort included 22 NICM patients (13 DCM, 9 CS) that underwent pre-procedural CMR prior to ventricular tachycardia (VT) ablation between November 2018 to May 2023. LGE images were delineated into sub-endocardial, mid-myocardial, and sub-epicardial layers, categorized into anterior, lateral, inferior, and septal walls based on the AHA 17 segment model for LV myocardial segmentation. CMR signal intensities were standardized as z-scores: z = (x−μ)/σ, where x is the MRI signal intensity for a specific myocardial segment and layer, and μ and σ are the mean and standard deviation across all myocardial segments and layers of the LV, to characterize regional intensity variations.

Results/Data: Compared to patients with DCM, those with CS 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 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 5-fold cross-validation.

Conclusions: 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.