Hepatic magnetic resonance T1-mapping and extracellular volume fraction compared to shear-wave elastography in pediatric Fontan-associated liver disease

Abstract

Background: Children with Fontan circulation are at risk of developing hepatic fibrosis/cirrhosis. Reliable noninvasive monitoring techniques are lacking or under development.

Objective: To investigate surrogate indicators of hepatic fibrosis in adolescents with Fontan circulation by evaluating hepatic magnetic resonance (MR) T1 mapping and extracellular volume fraction measurements compared to US shear-wave elastography.

Materials and methods: We analyzed hepatic native T1 times and extracellular volume fractions with modified Look-Locker inversion recovery. Liver stiffness was analyzed with shear-wave elastography. We compared results between 45 pediatric patients ages 16.7±0.6 years with Fontan circulation and 15 healthy controls ages 19.2±1.2 years. Measurements were correlated to clinical and hemodynamic data from cardiac catheterization.

Results: MR mapping was successful in 35/45 patients, revealing higher hepatic T1 times (774±44 ms) than in controls (632±52 ms; P<0.001) and higher extracellular volume fractions (47.4±5.0%) than in controls (34.6±3.8%; P<0.001). Liver stiffness was 1.91±0.13 m/s in patients vs. 1.20±0.10 m/s in controls (P<0.001). Native T1 times correlated with central venous pressures (r=0.5, P=0.007). Native T1 was not correlated with elastography in patients (r=0.2, P=0.1) or controls (r = -0.3, P=0.3). Extracellular volume fraction was correlated with elastography in patients (r=0.5, P=0.005) but not in controls (r=0.2, P=0.6).

Conclusion: Increased hepatic MR relaxometry and shear-wave elastography values in adolescents with Fontan circulation suggested the presence of hepatic fibrosis or congestion. Central venous pressure was related to T1 times. Changes were detected differently with MR relaxometry and elastography; thus, these techniques should not be used interchangeably in monitoring hepatic fibrosis.

Keywords: Adolescents; Chronic liver disease; Fontan procedure; Liver; Magnetic resonance imaging; Ultrasonographic elastography.

Fig. 1

Images of shear-wave elastography and native MR T1 mapping in an 18-year-old male control subject. a Shear-wave elastography. The blue color in the region of interest (yellow circle) indicates a normal value <1.4 m/s. b Native MR T1 map shows a relatively uniform color; white circles indicate five regions of interest in the liver (1–5), one in the spleen (6), one in the inferior caval vein (7) and one in the aorta (8)

Fig. 2

Images of shear-wave elastography and native MR T1 mapping in a 15-year old girl with Fontan circulation. a Shear-wave elastography. The colors in the region of interest (yellow circle) indicate an increased value of 1.9 m/s. b Native MR T1 map shows an uneven color distribution. White circles indicate five regions of interest within the liver (1–5), one in the spleen (6), one in the inferior caval vein (7) and one in the aorta (8)

Fig. 3

Graphs show MR results in the Fontan group compared to the control group. a, b Native T1 times (a) and extracellular volume fractions (b) are higher in the Fontan group

Fig. 4

Graph shows liver stiffness measured with US shear-wave elastography in the Fontan and control groups

Fig. 5

Bland–Altman plots show observer variation results. a–d Intraobserver (a and c) and interobserver (b and d) agreements analyzed for MR native T1 times in the Fontan group (a, b) and the control group (c, d). Results for the MR of extracellular volume fraction are shown in Online Supplementary Material 2. COV coefficient of variation