Abdominal MRI scans already performed to monitor liver disease in people with Fontan circulation can double as a tool for measuring skeletal muscle mass, according to a new retrospective study published in Pediatric Radiology. The researchers found that imaging-defined low muscle mass was common in both children and adults with this single-ventricle heart condition, appearing in roughly three in ten children and two in ten adults examined.
The altered physiology, exercise limitation, nutritional challenges, and chronic liver disease that accompany it leave patients vulnerable to reduced skeletal muscle mass. Because these patients also undergo regular abdominal MRI to surveil Fontan-associated liver disease, known as FALD, the research team asked whether those clinically acquired scans could be repurposed to assess muscle without any additional imaging.
The single-center, cross-sectional study included 124 individuals with Fontan circulation who had undergone abdominal MRI for FALD surveillance. Of these, 78 participants, or 63 percent, were male. The cohort comprised 57 children aged 3.2 to 17.4 years, with a median age of 14.1 years, and 67 adults aged 18.1 to 43.7 years, with a median age of 22.3 years.
The investigators used age-appropriate published measurement approaches, applying pediatric total psoas area for the children and adult total skeletal muscle index for the adults, and analyzed the two groups separately. Low muscle mass was identified in 17 of 57 children, or 30 percent, and 14 of 67 adults, or 21 percent, using these pediatric- and adult-specific techniques.
Beyond measuring muscle, the team secondarily explored whether low muscle mass was associated with clinical and imaging markers related to FALD. Continuous variables were summarized with medians and interquartile ranges and examined using Spearman correlations and Mann-Whitney U tests, while sparse cardiac and outcome data were treated descriptively.
The exploratory analyses did not identify a consistent pattern linking low muscle mass with the available FALD-related measures, which included liver stiffness measurement, liver biochemistries, and liver scoring systems. Several comparisons, including those involving ejection fractions and aortopulmonary collateral flow, were limited by missing data, small subgroups, and few outcome events, so no firm conclusions could be drawn about those relationships.
The authors conclude that clinically acquired liver MRI examinations can be repurposed to identify imaging-defined low muscle mass in individuals with Fontan circulation, offering a way to extract additional clinically relevant information from scans patients already receive. They note that the frequency of low muscle mass observed in both age groups supports prospective evaluation of standardized MRI measurements combined with muscle function, exercise capacity, and longitudinal outcomes.
As a retrospective, single-center, cross-sectional study, the work establishes feasibility and prevalence estimates rather than causal relationships or prognostic predictions. The authors frame their findings as groundwork: the observed frequencies justify future prospective studies that pair standardized MRI muscle measurements with functional testing and long-term follow-up to determine what imaging-defined low muscle mass means for the health of children and adults living with Fontan circulation.
Subject of Research: Opportunistic MRI measurement of skeletal muscle mass in children and adults with Fontan circulation
Article Title: Opportunistic MRI assessment of skeletal muscle mass in children and adults with Fontan circulation
Article References: Kong, T. Y., Razavi, J., Dillman, J. R., Hegde, S., Somasundaram, E., Morin, C. E., & Bonn, J. (2026). Opportunistic MRI assessment of skeletal muscle mass in children and adults with Fontan circulation. Pediatric Radiology. https://doi.org/10.1007/s00247-026-06824-7
Image Credits: AI Generated
DOI: 10.1007/s00247-026-06824-7
Keywords: Fontan circulation, skeletal muscle mass, MRI, Pediatric Radiology, FALD, liver disease surveillance, congenital heart disease, psoas area, retrospective study, cross-sectional study, Opportunistic, assessment
News Source: Harold Sullivan. (October 29, 2026). Liver MRI Scans Reveal Low Muscle Mass in Many Fontan Patients. Scienmag.
