Ultrasound-based attenuation imaging values increased with hepatic steatosis severity in pediatric patients with overweight or obesity in a prospective, single-center, cross-sectional study, although the findings were not validated against magnetic resonance imaging proton density fat fraction or histology.
The study included 653 children who underwent liver ultrasound at Shenzhen Children’s Hospital in China from October 2023 to June 2024. Following exclusions for liver and endocrine disorders and unsuccessful attenuation imaging procedures, the final cohort included 97 children with overweight, 292 with obesity, and 264 healthy-weight controls.
Researchers used attenuation imaging to calculate the liver attenuation coefficient, a quantitative ultrasound measure intended to reflect hepatic fat-related acoustic attenuation. Median attenuation imaging values were 0.51 dB/cm/MHz in healthy-weight controls, 0.54 dB/cm/MHz in children with overweight, and 0.64 dB/cm/MHz in children with obesity.
Among children with overweight or obesity, visual ultrasound grading identified no steatosis in 216 patients, mild steatosis in 142, moderate steatosis in 22, and severe steatosis in nine. Median attenuation imaging values increased stepwise across steatosis grades, from 0.53 dB/cm/MHz in patients without steatosis to 0.77, 0.85, and 0.89 dB/cm/MHz in those with mild, moderate, and severe steatosis, respectively.
The investigators reported a strong association between attenuation imaging values and steatosis grade by eta-squared analysis (η² = 0.626), suggesting that steatosis grade accounted for a substantial proportion of attenuation imaging variability in the cohort. However, attenuation imaging values did not significantly differ between the moderate and severe steatosis groups, and the small number of patients in those subgroups likely limited statistical power to detect higher-grade differences.
Importantly, the reference comparator was visual ultrasound grading rather than magnetic resonance imaging proton density fat fraction (MRI-PDFF) or biopsy. Because conventional ultrasound has recognized limitations for quantitative steatosis assessment, the observed attenuation imaging correlations should be interpreted within the constraints of that reference standard.
Attenuation imaging values also correlated with several anthropometric and metabolic measures among children with overweight or obesity, including age, body mass index, skin-to-liver distance, alanine aminotransferase, aspartate aminotransferase, triglycerides, uric acid, and high-density lipoprotein cholesterol. The strongest reported correlation was with alanine aminotransferase. No significant correlation was observed with sex.
In subgroup analyses, attenuation imaging values did not significantly correlate with shear wave elasticity, shear wave speed, or shear wave dispersion measurements among patients who underwent those assessments, suggesting attenuation imaging may capture a different tissue characteristic than elastography-based parameters.
The study also found that children with overweight or obesity but no ultrasonographic steatosis had slightly higher attenuation imaging values than healthy-weight controls, at 0.53 vs 0.51 dB/cm/MHz. The researchers cautioned that the clinical significance of this small difference remains uncertain and that abdominal wall thickness or subcutaneous fat composition may have influenced the measurements.
The control-group attenuation imaging values were generally consistent with two prior pediatric studies but differed from another published cohort, highlighting the possibility that attenuation imaging reference ranges may vary by population and ultrasound platform.
Additional limitations included the lack of MRI-PDFF or histologic validation, absence of formal intraobserver and interobserver reproducibility testing, and the study’s single-center South China cohort, which may limit generalizability.
“Broad generalization of these results is not warranted,” wrote Tingting Liu, of Shenzhen Children’s Hospital in Shenzhen, China, and colleagues.
The researchers said future multicenter studies incorporating MRI-PDFF, standardized attenuation imaging protocols across platforms, and histologic validation in selected patients will be needed to establish the clinical utility of attenuation imaging in pediatric metabolic-associated steatotic liver disease.
The researchers reported no competing interests.
Source: Insights into Imaging