Interobserver Agreement in Contrast-enhanced US for Hepatic Nodules in Patients with Fontan-associated Liver Disease

Background The Fontan procedure for single-ventricle congenital heart disease enables survival into adulthood but causes Fontan-associated liver disease (FALD), characterized by progressive hepatic fibrosis and hepatic nodules. Contrast-enhanced US (CEUS) is a proven method to evaluate hepatic nodules, but CEUS findings of FALD nodules have not been systematically described. Purpose To evaluate hepatic CEUS findings and assess interobserver agreement in CEUS interpretations in participants with FALD. Materials and Methods This single-center prospective study included participants with FALD who underwent hepatic CEUS between June 2018 and December 2023. Imaging was evaluated blindly by two CEUS-specialized physicians. Clinical variables were collected via chart review, and biopsy diagnoses were obtained from pathologic examination. Interobserver variability in CEUS findings and diagnoses was quantified using Cohen κ, reported as means and standard errors. Results This study included 32 participants (mean age, 30 years ± 8.7 [SD]; 19 male). Thirty-five hepatic nodules were evaluated, including 20 (57%) focal nodular hyperplasia-like lesions, seven (20%) regenerative nodules, five (14%) hemangiomas, and three (9%) possible malignancies. Interobserver agreement was 100% (κ = 1; no disagreements observed) for CEUS-guided nodule diagnoses. Interobserver agreement was also 100% for CEUS findings, except arterial phase hepatic enhancement pattern (mean κ = 0.92; standard error = 0.07) and lesion echogenicity (mean κ = 0.55; standard error = 0.13). For five biopsied FALD nodules, CEUS diagnosis agreed with pathologic diagnosis, except for one diagnosis of possible malignancy that was biopsy-proven benign adenoma. Washout was seen in 38% (11 of 29) of nodules evaluated with multiphase abdominal CT or MRI. However, at CEUS, only 14% (four of 29) exhibited washout. Conclusion In participants with FALD, there was excellent interobserver agreement in the evaluation of FALD nodules at hepatic CEUS, and CEUS diagnoses mostly agreed with pathologic diagnoses in the subset of cases with biopsies, including for malignant lesions and lesions requiring follow-up. © RSNA, 2026 See also the editorial by Barr in this issue.