Assessment of MRI-Derived proton density fat fraction of total subcutaneous adipose tissue for discrimination primary aldosteronism subtypes.

PURPOSE: Distinguishing unilateral aldosterone-producing adenoma (APA) from bilateral adrenocortical hyperplasia (BAH) in primary aldosteronism (PA) dictates differential management. The current study aimed to find non-invasive biomarkers for subtype classification of PA. METHODS: PA subtypes in the cross-sectional study were confirmed via adrenal vein sampling (AVS) and/ or histopathology. Abdominal adipose tissue volumes, including total visceral adipose tissue (TVAT), total subcutaneous adipose tissue (TSAT), and the 11th thoracic to first lumbar vertebra (T11-L1) layers, were quantified using proton-density fat fraction magnetic resonance imaging (MR-PDFF). Diagnostic efficacy was assessed via logistic regression and receiver-operating-characteristic (ROC) analyses. RESULTS: A total of 74 patients were enrolled in the study (mean age 46.6 ± 12.3 years; 50% male), including 22 with essential hypertension (EH) and 52 with PA. Quantitative MR indicated significantly lower TSAT in patients with PA compared to those with EH (p < 0.05), while TVAT showed no significant difference. Compared to both EH and BAH groups, the APA group exhibited significantly lower TSAT and T11-L1 SAT (p < 0.05). Multivariate logistic regression model indicated that TSAT as a potential discriminator between APA and BAH (AUC 0.834; cut-off value: 956.2‰). Consistent with this, random forest analysis supported a major role for TSAT in PA subtype classification (overall accuracy 90.38%). CONCLUSION: This study suggests that MRI-quantified TSAT shows promising discriminative capacity for distinguishing subtype classification of PA, indicating its possible role as an imaging-based adjunctive tool with prospective clinical utility in patient stratification.