Background: Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in children in certain regions and is rising in prevalence with increasing obesity. Accurate noninvasive imaging methods for diagnosing and quantifying liver fat are needed to guide NAFLD management. Objective: To evaluate four ultrasound technologies for quantitative assessment of liver fat content in children, using MRI proton density fat fraction (PDFF) as reference standard. Methods: This prospective study enrolled children who underwent clinical abdominal MRI without general anesthesia between November 2018 and July 2019. Patients underwent investigational liver ultrasound within a day of 1.5 or 3T MRI. Acquired ultrasound radiofrequency data were processed offline to compute acoustic attenuation coefficient, hepatorenal index (HRI), Nakagami parameter, and shear wave elastography (SWE) parameters (elasticity, viscosity and dispersion). Ultrasound parameters were compared to MRI PDFF obtained using a multi-echo sequence. A second observer independently performed offline attenuation coefficient and HRI measurements in all patients. Results: A total of 48 patients were enrolled: 22 girls, 26 boys; mean age 13 years (range, 7-17 years); mean body mass index 22.25 kg/m2 (range, 14.5-48.1 kg/m2). A total of 21% (10/48) had steatosis (PDFF >5%). PDFF was correlated with attenuation coefficient (r=0.76, 95% CI 0.60-0.86, p<.001), HRI (r=0.84, 95% CI 0.74-0.91, p<.001), and Nakagami parameter (r=0.55, 95% CI, 0.32-0.72, p<.001), but not SWE parameters (r=0.05-0.25; p>.05). In patients with no, mild, moderate, and severe steatosis based on PDFF, mean±SD attenuation coefficient was 0.48±0.08, 0.54±0.03, 0.57±0.04, and 0.86±0.07 dB/cm/MHz, and mean±SD HRI was 1.28±0.30, 1.59±0.23, 2.25±0.04, and 3.06±0.49. For attenuation coefficient, threshold of 0.54 dB/cm/MHz achieved sensitivity 80% and specificity 82% for steatosis, and of 0.60 dB/cm/MHz achieved sensitivity 80% and specificity 98% for moderate steatosis. For HRI, threshold of 1.48 achieved sensitivity 90% and specificity 76% for steatosis, and of 2.11 achieved sensitivity 100% and specificity 100% for moderate steatosis. Inter-observer concordance coefficient was 0.92 for attenuation coefficient and 0.91 for HRI. Conclusion: Attenuation coefficient and HRI accurately detected and quantified liver fat in this small sample of children. Clinical Impact: Quantitative ultrasound parameters may guide NAFLD diagnosis and management in children.
View details for DOI 10.2214/AJR.20.24874
View details for PubMedID 33438457