Objectives: To determine the prevalence of nonalcoholic fatty liver disease (NAFLD) in children with obesity because current estimates range from 1.7% to 85%. A second objective was to evaluate the diagnostic accuracy of alanine aminotransferase (ALT) for NAFLD in children with obesity. Study Design:We evaluated children ages 9-17 years with obesity for the presence of NAFLD. Diseases other than NAFLD were excluded by history and laboratories. Hepatic steatosis was measured by liver magnetic resonance imaging (MRI) proton density fat fraction (PDFF). The diagnostic accuracy of ALT for detecting NAFLD was evaluated. Results:The study included 408 children with obesity that had a mean age of 13.2 years and mean BMI percentile of 98.0. The study population had a mean ALT of 32 U/L and median hepatic MRI-PDFF of 3.7%. The estimated prevalence of NAFLD was 26.0% (95% CI 24.2 -27.7), 29.4% in males (CI 26.1 -32.7%) and 22.6% in females (CI 16.0 -29.1%). Optimal ALT cut-point was 42 U/L (47.8% sensitivity, 93.2% specificity) for males and 30 U/L (52.1% sensitivity, 88.8% specificity) for females. CART model with sex, ALT, and insulin had 80% diagnostic accuracy for NAFLD.

Objectives: We sought to evaluate the relevance of pediatric dairy fat recommendations for children at risk for nonalcoholic fatty liver disease (NAFLD) by studying the association between dairy fat intake and the amount of liver fat. The effects of dairy fat may be mediated by odd chain fatty acids (OCFA), such as pentadecanoic acid (C15:0), and monomethyl branched chain fatty acids (BCFA), such as iso-heptadecanoic acid (iso-C17:0). Therefore, we also evaluated the association between plasma levels of OCFA and BCFA with the amount of liver fat. Methods: Observational, cross-sectional, community-based sample of 237 children ages 8 to 17. Dairy fat intake was assessed by 3 24-hour dietary recalls. Plasma fatty acids were measured by gas chromatography-mass spectrometry. Main outcome was hepatic steatosis measured by whole liver magnetic resonance imaging proton density fat fraction (MRI-PDFF). Results: Median dairy fat intake was 10.6 grams/day (range 0.0--44.5 g/day). Median liver MRI-PDFF was 4.5% (range 0.9%–45.1%). Dairy fat intake was inversely correlated with liver MRI-PDFF (r = −0.162; P = .012). In multivariable log linear regression, plasma C15:0 and iso-C17:0 were inverse predictors of liver MRI-PDFF (B = −0.247, P = 0.048; and B = −0.234, P = 0.009). Conclusions: Dairy fat intake, plasma C15:0, and plasma iso-C17:0 were inversely correlated with hepatic steatosis in children. These hypothesis-generating findings should be tested through clinical trials to better inform dietary guidelines.

Background Magnetic resonance elastography (MRE) can determine the presence and stage of liver fibrosis. Data on normative MRE values, while reported in adults, are limited in children. Purpose To determine the distribution of MRE‐measured liver stiffness in children without liver disease. Study Type Prospective, observational. Population Eighty‐one healthy children (mean 12.6 ± 2.6 years, range 8–17 years). Field Strength/Sequence 3.0T Signa HDxt, General Electric MR Scanner; 2D GRE MRE sequence. Assessment History, examination, laboratory evaluation, and (MR) exams (proton density fat fraction, PDFF, and MRE) were performed. MR elastograms were analyzed manually at two reading centers and compared with each other for agreement and with published values in healthy adults and thresholds for fibrosis in adult and pediatric patients. Statistical Tests Descriptive statistics, Bland–Altman analysis, t‐test to compare hepatic stiffness values with reference standards. Results Stiffness values obtained at both reading centers were similar, without significant bias (P = 0.362) and with excellent correlation (intraclass correlation coefficient [ICC] = 0.782). Mean hepatic stiffness value for the study population was 2.45 ± 0.35 kPa (95th percentile 3.19 kPa), which was significantly higher than reported values for healthy adult subjects (2.10 ± 0.23 kPa, P < 0.001). In all, 74–85% of subjects had stiffness measurements suggestive of no fibrosis. Data Conclusion Mean liver stiffness measured with MRE in this cohort was significantly higher than that reported in healthy adults. Despite rigorous screening, some healthy children had stiffness measurements suggestive of liver fibrosis using current published thresholds. Although MRE has the potential to provide noninvasive assessment in patients with suspected hepatic disease, further refinement of this technology will help advance its use as a diagnostic tool for evidence of fibrosis in pediatric populations. Level of Evidence: 1 Technical Efficacy: 5 J. Magn. Reson. Imaging 2020;51:919–927.