Diagnostic Accuracy of Magnetic Resonance Imaging Hepatic Proton Density Fat Fraction in Pediatric Nonalcoholic Fatty Liver Disease

ABSTRACT

We assessed the performance of magnetic resonance imaging (MRI) proton density fat fraction (PDFF) in children to stratify hepatic steatosis grade before and after treatment in the Cysteamine Bitartrate Delayed-Release for the Treatment of Nonalcoholic Fatty Liver Disease in Children (CyNCh) trial, using centrally-scored histology as reference. Participants had multi-echo 1.5T or 3T MRI on scanners from three manufacturers. Of 169 enrolled children, 110 (65%) and 83 (49%) had MRI and liver biopsy at baseline and at end-of-treatment (EOT; 52-weeks), respectively. At baseline, 17% (19/110), 28% (31/110), and 55% (60/110) of liver biopsies showed grades 1, 2, and 3 histologic steatosis; corresponding PDFF (mean ± standard deviation) values were 10.9 ± 4.1%, 18.4 ± 6.2%, and 25.7 ± 9.7%, respectively. PDFF classified grade 1 vs. 2-3 and 1-2 vs. 3 steatosis with areas under receiving operator characteristic curves (AUROCs) of 0.87 (95% confidence interval [CI]: 0.80, 0.94) and 0.79 (0.70, 0.87), respectively. PDFF cut-offs at 90% specificity were 17.5% for grades 2-3 steatosis, and 23.3% for grade 3 steatosis. At EOT, 47% (39/83), 41% (34/83), and 12% (10/83) of biopsies showed improved, unchanged, and worsened steatosis grade, respectively, with corresponding PDFF (mean ± standard deviation) changes of -7.8 ± 6.3%, -1.2 ± 7.8% and 4.9 ± 5.0%, respectively. PDFF change classified steatosis grade improvement and worsening with AUROCs (95% CIs) of 0.76 (0.66, 0.87) and 0.83 (0.73, 0.92), respectively. PDFF change cut-off values at 90% specificity were -11.0% and +5.5% for improvement and worsening. Conclusion: MRI-estimated PDFF has high diagnostic accuracy to both classify and predict histologic steatosis grade, and change in histologic steatosis grade in children with NAFLD. This article is protected by copyright. All rights reserved.

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