Associations Between Biochemical Risk Markers and MRI-Determined Ectopic Fat Distribution in Liver and Pancreas of Pediatric Obesity.

BACKGROUND

Ectopic fat deposition in the liver and pancreas is closely linked to metabolic dysfunction, a key driver of the global burden of chronic disease. However, studies on intra-organ distribution of ectopic fat in the pediatric obese population remain limited.

PURPOSE: To assess MRI-based spatial distribution patterns of hepatic and pancreatic fat using a fully automated nnU-Net model and evaluate their association with biochemical risk markers.

STUDY TYPE: Prospective.

SUBJECT: Eighty-one pediatric patients (age: 12 [11, 13] years, 57 males) with overweight or obesity based on body mass index z-score.

FIELD STRENGTH/SEQUENCE: 1.5 T, gradient-echo modified-DIXON T1W.

ASSESSMENT: The spatial distribution of fat in liver and pancreas, the correlations between hepatic and pancreatic fat fraction (FF), and the association between the fat measures and biochemical risk markers were evaluated.

STATISTICAL TESTS: Paired Wilcoxon test or t-test, repeated measure ANOVA or Friedman's test, Kruskal-Wallis test, Spearman correlation analysis. Significance was set at p < 0.05.

RESULTS

Hepatic FF was significantly higher in the right lobe (median, 16.22%) than in the left lobe (median, 10.43%), and increased with distance from the portal vein. The degree of hepatic fat heterogeneity increased with the amount of fat deposition (whole variance: Level 0: 4.10; Level 1: 11.53; Level 2: 28.94; Level 3: 31.21). Then, the FF and its variance in the pancreatic body and tail were significantly higher than those in the head. A weak but statistically significant correlation (r range, 0.29-0.38) was observed between hepatic and pancreatic FF. Hepatic FF correlated with triglyceride and apolipoprotein B, but pancreatic fat showed no association (p range, 0.096-0.994) with lipid profiles, HOMA-IR, or HOMA-β.

DATA

CONCLUSION

Intra-hepatic and intra-pancreatic fat were heterogeneously distributed in pediatric obese population. Although fat accumulation in the liver and pancreas was weakly correlated, hepatic and pancreatic fat may arise from distinct metabolic disorders.

EVIDENCE LEVEL: 2.

TECHNICAL EFFICACY: Stage 1.