T1-weighted dual-echo MRI for fat quantification in pediatric nonalcoholic fatty liver disease

AIM： To determine in obese children with nonalcoholic fatty liver disease （NAFLD） the accuracy of magnetic resonance imaging （MRI） in assessing liver fat concentration. METHODS： A case-control study was performed. Cases were 25 obese children with biopsy-proven NAFLD. Controls were 25 obese children matched for age and gender, without NAFLD at ultrasonography and with normal levels of aminotransferases and insulin. Hepatic fat fraction （HFF） by MRI was obtained using a modification of the Dixon method.RESULTS： HFF ranged from 2% to 44% [mean, 19.0% （95% CI, 15.1-27.4）] in children with NAFLD, while in the controls this value ranged from 0.08% to 4.69% [2.0% （1.3-2.5）, P 〈 0.0001]. HFF was highly correlated with histological steatosis （r = 0.883, P 〈 0.0001） in the NAFLD children. According to the histological grade of steatosis, the mean HFF was 8.7% （95% CI, 6.0-11.6） for mild, 21.6% （15.3-27.0） for moderate, and 39.7% （34.4-45.0） for severe fatty liver infiltration. With a cutoff of 4.85%, HFF had a sensitivity of 95.8% for the diagnosis of histological steato- sis ≥ 5%. All control children had HFF lower than 4.85%; thus, the specificity was 100%. Alter 12 mo, children with weight loss displayed a significant decrease in HFF. CONCLUSION： MRI is an accurate methodology for liver fat quantification in pediatric NAFLD.