T1 mapping of the myocardium and liver in the single ventricle population

Background Fontan associated liver disease (FALD) is an increasingly recognized complication of the single ventricle circulation characterized by hepatic venous congestion leading to hepatic fibrosis. Within the Fontan myocardium, fibrotic myocardial remodeling may occur and lead to ventricular dysfunction. Magnetic resonance imaging (MRI) T1 mapping can characterize both myocardial and liver properties. Objective The aim of this study was to compare myocardial and liver T1 between single ventricle patients with and without a Fontan and biventricular controls.Materials and methods A retrospective study of 3 groups of patients: 16 single ventricle patients before Fontan (SVpre 2 newborns, 9 pre-Glenn, 5 pre-Fontan, 31% single right ventricle [SRV]), 16 Fontans (56% SRV) and 10 repaired d-transposition of the great arteries (TGA). Native modified Look-Locker inversion T1 times were measured in the myocardium and liver. Cardiac MRI parameters, myocardial and liver T1 values were compared in the three groups. Correlations were assessed between liver T1 and cardiac parameters. Results Myocardial T1 was higher in SVpre (1,056 +/- 48 ms) and Fontans (1,047 +/- 41 ms) compared to TGA (1,012 +/- 48 ms, P < 0.05). Increased liver T1 was found in both SVpre (683 +/- 82 ms) and Fontan (727 +/- 49 ms) patients compared to TGA patients (587 +/- 58 ms, P < 0.001). There was no difference between single left ventricle (SLV) versus SRV myocardial or liver T1. Liver T1 showed moderate correlations with myocardial T1 (r = 0.48, confidence interval [CI] 0.26-0.72) and ejection fraction (r =-0.36, CI-0.66-0.95) but not with other volumetric parameters.Conclusion Increased liver T1 at both pre-and post-Fontan stages suggests there are intrinsic liver abnormalities early in the course of single ventricle palliation. Increased myocardial T1 and its relationship to liver T1 suggest a combination of edema from passive venous congestion and/or myocardial fibrosis occurring in this population. Liver T1 may provide an earlier marker of liver disease warranting further study.