Liver T1 mapping in Fontan patients and patients with biventricular congenital heart disease - insights into the effects of venous congestions on diffuse liver disease.

T1 relaxation time quantification on parametric maps is routinely used in cardiac imaging and may serve as a non-invasive biomarker for diffuse liver disease. In this study, we aimed to investigate the relationship between liver T1 values and cardiac function in patients with congenital heart disease (CHD) and compared patients with a biventricular circulation (BVC) to those with a Fontan circulation (FC). Magnetic resonance images from patients with CHD, obtained between June and December 2023 on a 1.5 T machine, were retrospectively reviewed. The examinations included cardiac cine sequences to assess ventricular mass and volumes, along with liver T1 mapping. T1 values were measured in eight liver segments and were compared with ventricular mass and volumes in patients with BVC and FC. In total, 104 patients (75 with BVC and 29 with FC) were included. T1 values varied significantly among the eight liver segments in both patient groups. In an age-matched comparison, patients with FC had significantly higher T1 values in all liver segments. In patients with BVC and right ventricular (RV) enlargement, a positive correlation between RV volume and T1 values in the right liver lobe was found (R > 0.504, p < 0.033). In patients with FC, the T1 values did not differ between patients with an extracardiac conduit or a lateral tunnel. Liver T1 mapping suggests more severe liver affection in patients with FC compared to those with BVC. It seems a valuable addition to cardiovascular magnetic resonance for patients who are at risk of systemic venous congestion.