Sonographic findings in fontan-associated liver disease across pediatric and adult patients: A cross-sectional imaging study.

BACKGROUND: This study aimed to characterize sonographic hepatic findings across pediatric, adolescent, and adult Fontan patients and to examine their cross-sectional relationships with time since Fontan completion and chronological age. As a secondary objective, we explored a composite score integrating complementary sonographic findings.

MATERIALS AND METHODS: In this retrospective cross-sectional analysis of a prospectively established single-center Fontan cohort, hepatic ultrasound findings from 153 patients were evaluated, including gray-scale imaging, Doppler assessment, and shear-wave elastography performed according to institutional acquisition protocols. Individual sonographic findings were analyzed as the primary imaging outcomes. Cross-sectional associations with time since Fontan completion were assessed using sex-adjusted regression models; additional models simultaneously included chronological age, time since Fontan completion, and sex to examine their closely related contributions. A secondary exploratory 5-point composite score integrating five complementary sonographic domains was evaluated descriptively.

RESULTS: Longer time since Fontan completion was associated cross-sectionally with greater IVC diameter, liver size, shear-wave velocity, structural abnormality, and hepatic nodularity in sex-adjusted analyses. Chronological age and time since Fontan completion were nearly collinear (r = 0.970). When both variables and sex were included simultaneously, associations with IVC diameter, liver size, shear-wave velocity, and structural classification were attenuated and no longer statistically significant, whereas hepatic nodularity remained associated with time since Fontan completion (OR = 1.22/year; 95% CI 1.03-1.45; p = 0.024). Complete composite-score data were available in 101 patients; mean scores were 0.81 ± 0.88, 2.15 ± 1.26, 3.18 ± 0.80, and 4.27 ± 0.80 across < 5-, 5-<10-, 10-<20-, and ≥ 20-year post-Fontan categories, respectively. In 15 patients with serial examinations, scores were higher at the later examination in 10 and unchanged in five (p = 0.004). In a stratified subset of 40 independently reread examinations, interobserver agreement was high for liver size (ICC = 0.922) and IVC diameter (ICC = 0.947), whereas agreement for qualitative sonographic findings was lower (κ = 0.202-0.369).

CONCLUSION: Sonographic vascular, morphologic, structural, elastographic, and nodular abnormalities differed across patients examined at increasing intervals after Fontan completion. However, because chronological age and Fontan duration were nearly collinear, this cross-sectional study cannot determine whether these imaging gradients reflect duration of Fontan physiology, chronological maturation, or both. Hepatic nodularity showed the most robust association with time since Fontan completion in simultaneous models. The composite score provides a secondary exploratory framework for integrating complementary sonographic findings but requires prospective longitudinal and external validation. The limited interobserver agreement for qualitative findings further emphasizes the need for standardized image interpretation and supports the exploratory status of the composite score.