To determine whether abdominal magnetic resonance imaging (MRI) detects hepatic abnormalities before clinical or biochemical perturbations in patients after the Fontan procedure.

Thirty-nine children and adolescents who underwent the Fontan procedure and were referred to a pediatric hepatologist by cardiology services between 2011 and 2012 were reviewed retrospectively. Physical examination findings, routine laboratory tests of liver function, evaluation for chronic liver disease, and abdominal MRI findings were recorded. MRI findings were evaluated relative to time elapsed since surgery by 2 radiologists (blinded).

Assessment for coexisting chronic liver disease was negative in all patients. All patients had a normal serum albumin level and International Normalized Ratio. Twenty-six of the 39 patients (67%) underwent abdominal MRI, 4 had MRI-incompatible hardware, and 9 did not undergo MRI because of insurance denial. All MRI scans demonstrated morphologic liver changes with varying degrees of reticular contrast enhancement compatible with fibrosis and congestion. Reticular contrast enhancement was often nonuniform, and 9 patients (35%) had multifocal arterially enhancing lesions.

MRI can identify hepatic abnormalities in patients after Fontan surgery that go undetected by standard clinical and laboratory assessments. These abnormalities are not uniformly distributed throughout the liver, and thus assessment by liver biopsy analysis is subject to sampling error.