Background Childhood obesity is rising worldwide, leading to an increased prevalence of metabolic dysfunction-associated steatotic liver disease, the most common pediatric liver disease. Ultrasound-derived fat fraction (UDFF) is a recently developed technique for quantifying hepatic fat that has been validated in children, providing a rapid, reliable, and non-invasive alternative to conventional imaging. Objective To evaluate the association between weight status, expressed as body mass index (BMI) z-score, and UDFF in a pediatric population without underlying liver disease. Materials and methods Abdominal ultrasounds including a UDFF measurement in patients without liver disease were retrospectively evaluated. We calculated the BMI z-score for all patients and classified them as normal weight (zBMI) or overweight (zBMI≥1). UDFF values were compared across zBMI categories, sex and ethnicity (Hispanic/Latino or non-Hispanic/non-Latino), using chi-square tests (P<0.05). Pearson’s correlation was used to assess the relationship between continuous UDFF values and zBMI. Logistic regression analyses were performed to assess associations between elevated UDFF (>6%) and adiposity markers (zBMI and ultrasound-measured abdominal wall thickness (AWT)), as well as ethnicity. Results Of 223 subjects, 93 (41 males/52 females, mean age of 8.2 years) met the inclusion criteria. In the normal-weight population (n=46), 41 (89.1%) had normal UDFF, and 5 (10.9%) had elevated UDFF. In the overweight group (n =47), 29 (61.7%) had normal UDFF and 18 (38.3%) had elevated UDFF. UDFF values showed a positive correlation with zBMI, and higher zBMI increased the odds of elevated UDFF. In the multivariable model including zBMI, AWT, and ethnicity, ultrasound-measured abdominal wall thickness was the strongest predictor of elevated UDFF. Conclusion BMI z-score was positively associated with hepatic fat content and with higher odds of elevated UDFF. When multiple factors were considered together, ultrasound-measured abdominal wall thickness showed the strongest independent association with elevated UDFF supporting the central role of adiposity in pediatric hepatic fat accumulation. UDFF may serve as a valuable complement to routine clinical markers, using zBMI, for early identification of children with hepatic steatosis. Larger prospective studies are needed to define its role in clinical practice.

Exploring the association between BMI and liver fat in children: a study using ultrasound-derived fat fraction (UDFF)

期刊论文
发表日期：

2025年12月23日

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Marine Moeremans,
Richard A. Barth,
Max Zalcman,
Erika Rubesova

摘要

Background

Childhood obesity is rising worldwide, leading to an increased prevalence of metabolic dysfunction-associated steatotic liver disease, the most common pediatric liver disease. Ultrasound-derived fat fraction (UDFF) is a recently developed technique for quantifying hepatic fat that has been validated in children, providing a rapid, reliable, and non-invasive alternative to conventional imaging.

Objective

To evaluate the association between weight status, expressed as body mass index (BMI) z-score, and UDFF in a pediatric population without underlying liver disease.

Materials and methods

Abdominal ultrasounds including a UDFF measurement in patients without liver disease were retrospectively evaluated. We calculated the BMI z-score for all patients and classified them as normal weight (zBMI) or overweight (zBMI≥1). UDFF values were compared across zBMI categories, sex and ethnicity (Hispanic/Latino or non-Hispanic/non-Latino), using chi-square tests (P<0.05). Pearson’s correlation was used to assess the relationship between continuous UDFF values and zBMI. Logistic regression analyses were performed to assess associations between elevated UDFF (>6%) and adiposity markers (zBMI and ultrasound-measured abdominal wall thickness (AWT)), as well as ethnicity.

Results

Of 223 subjects, 93 (41 males/52 females, mean age of 8.2 years) met the inclusion criteria. In the normal-weight population (n=46), 41 (89.1%) had normal UDFF, and 5 (10.9%) had elevated UDFF. In the overweight group (n =47), 29 (61.7%) had normal UDFF and 18 (38.3%) had elevated UDFF. UDFF values showed a positive correlation with zBMI, and higher zBMI increased the odds of elevated UDFF. In the multivariable model including zBMI, AWT, and ethnicity, ultrasound-measured abdominal wall thickness was the strongest predictor of elevated UDFF.

Conclusion

BMI z-score was positively associated with hepatic fat content and with higher odds of elevated UDFF. When multiple factors were considered together, ultrasound-measured abdominal wall thickness showed the strongest independent association with elevated UDFF supporting the central role of adiposity in pediatric hepatic fat accumulation. UDFF may serve as a valuable complement to routine clinical markers, using zBMI, for early identification of children with hepatic steatosis. Larger prospective studies are needed to define its role in clinical practice.