Ultrasound of the rectus femoris as a novel tool to measure sarcopenia in pediatric chronic liver disease.

BACKGROUND

Sarcopenia, assessed by psoas muscle CT or MRI, predicts adverse outcomes in adults with advanced chronic liver disease (CLD). However, these radiologic techniques are understudied in children. Ultrasound (US) measures of leg muscle quality and quantity potentially offer a novel, safe, and practical means to assess sarcopenia in pediatric patients.

METHODS

We prospectively enrolled pediatric patients (age ≤18) with and without CLD. US of the rectus femoris muscle was performed in triplicate for cross-sectional area (CSA), muscle thickness (MT), echogenic intensity (EI), and fascicle length (FL, calculated). Muscle measures were assessed for intra-rater reliability by intraclass correlation coefficients (ICC) and association with CLD, PELD/MELD, and body mass index (BMI) z-score using logistic regression, linear regression, and Pearson correlation, respectively.

RESULTS

Among 156 participants (N=69 CLD, N=85 healthy), reliability was excellent for CSA, MT, and EI, with ICC ranging from 0.946 (95% CI 0.929-0.959) for EI-right to 0.998 (95% CI 0.998-0.999) for CSA-left, and good for FL (right 0.823, 95% CI 0.769-0.866; left 0.768, 95% CI 0.698-0.825). In age-adjusted and sex-adjusted logistic regression, CLD likelihood decreased with increasing MT and FL (per unit increase: OR=0.82, 95% CI 0.71-0.96; OR=0.99, 95% CI 0.97-0.99) and CLD likelihood increased with increasing EI (OR=1.04, 95% CI 1.01-1.08) for right-side measures (but not left-side). Among CLD, all muscle measures, except EI, were positively correlated with BMI z-score and negatively associated with PELD/MELD score after age-adjustment and sex-adjustment.

CONCLUSIONS

Pediatric ultrasound of the rectus femoris muscle demonstrates excellent intra-rater reliability, correlates with measures of malnutrition (BMI) and distinguishes CLD from healthy participants. This may offer a novel tool for assessing sarcopenia and liver disease severity in pediatric CLD.