Coincident with the rise in prevalence of childhood and adolescent obesity over the past few decades, nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease in children in the United States.^1,2 NAFLD encompasses a range of severity from bland steatosis to nonalcoholic steatohepatitis (NASH) that may ultimately result in advanced fibrosis, cirrhosis, and hepatocellular carcinoma.³ Cirrhosis due to NAFLD has been described in children.⁴ Presence of NAFLD in children independently increases risks for cardiovascular disease.⁵

Purpose: To compare PRESS and STEAM MR spectroscopy for assessment of liver fat in human subjects.Materials and Methods: Single‐voxel (20 × 20 × 20 mm) PRESS and STEAM spectra were obtained at 1.5T in 49 human subjects with known or suspected fatty liver disease. PRESS and STEAM sequences were obtained with fixed TR (1500 msec) and different TE (five PRESS spectra between TE 30‐70 msec, five STEAM spectra between TE 20–60 msec). Spectra were quantified and T2 and T2‐corrected peak area were calculated by different techniques. The values were compared for PRESS and STEAM.Results: Water T2 values from PRESS and STEAM were not significantly different (P = 0.33). Fat peak T2s were 25%–50% shorter on PRESS than on STEAM (P < 0.02 for all comparisons) and there was no correlation between T2s of individual peaks. PRESS systematically overestimated the relative fat peak areas (by 7%–263%) compared to STEAM (P < 0.005 for all comparisons). The peak area given by PRESS was more dependent on the T2‐correction technique than STEAM.Conclusion: Measured liver fat depends on the MRS sequence used. Compared to STEAM, PRESS underestimates T2 values of fat, overestimates fat fraction, and provides a less consistent fat fraction estimate, probably due to J coupling effects. J. Magn. Reson. Imaging 2009;30:145–152.

Onent features are associated with specific histological features or severity of NAFLD. METHODS: Children and adolescents aged 6–17 years enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) with clinical data obtained within 6 months of liver biopsy were included. MetS was defined as the presence of three or more of the following features as determined by application of age-adjusted normative values: central obesity, dyslipidemia, impaired fasting glucose, and elevated blood pressure. Liver biopsies were evaluated by the Pathology Committee of the NASH CRN. RESULTS: Two hundred fifty four children were included in the analysis, of whom 65 (26%) met specified criteria for MetS. Among children with MetS, there is a higher proportion of females who were on average older in age and pubertal. The risk of MetS was greatest among those with severe steatosis (odds ratio (OR)=2.58 for grade 3 vs. grade 1 steatosis,P=0.001). The presence of hepatocellular ballooning was also significantly associated with MetS (OR=2.10,P=0.03). Those with advanced fibrosis (stage 3/4) had an OR for MetS of 3.21 (P=0.04) vs. those without fibrosis (stage 0). Borderline zone 1 or definite NASH patterns compared with “not NASH” were strongly associated with MetS (OR=4.44,P=0.005 and OR=4.07,P=0.002, respectively). The mean NAFLD Activity Score (NAS) was greater among children with MetS vs. those without (4.8 ± 1.4 vs. 4.3 ± 1.4,P=0.01). Central obesity was significantly associated with steatosis, fibrosis, hepatocellular ballooning, and NAFLD pattern. Insulin resistance was significantly associated with steatosis, fibrosis, hepatocellular ballooning, NAS, and NAFLD pattern. CONCLUSIONS: MetS is common among children with NAFLD and is associated with severity of steatosis, hepatocellular ballooning, NAS, NAFLD pattern, and the presence of advanced fibrosis. Individual MetS features, particularly central obesity and insulin resistance, were also associated with severity of NAFLD. MetS features should be considered in children with NAFLD as individually and collectively they help identify children with more advanced disease....