Fontan-Associated Liver Disease: Quantification and Visualization of Abdominal Hemodynamics by 4D Flow MRI

Background: Liver fibrosis has been recognized as a long-term morbidity associated with Fontan circulation (Fontan associated liver disease [FALD]). Chronic central venous congestion is suspected to be the main driver of FALD. The optimal imaging modality to screen for FALD and to monitor progression has not yet been defined. The study aimed to quantitatively evaluate liver hemodynamics with four-dimensional phase contrast flow magnetic resonance imaging (4D PC flow MRI).

Method: Fontan patients (n = 22) underwent an MRI protocol with 4D flow MRI at 1.5 Tesla (Magnetom Aera, Siemens Healthcare, Erlangen, Germany) assessing portal, splenic and hepatic venous blood flow and derived parameters including wall shear stress. Regions of interest included the superior mesenteric vein, portal vein, splenic vein, left and right portal vein branch, right hepatic vein, and inferior vena cava. 4D PC flow MRI datasets were evaluated using a dedicated software (GTflow, Gyrotools, Switzerland). Routine FALD screening included abdominal ultrasound and laboratory testing. Severity was graded based on ultrasound and laboratory abnormalities.

Results: Median age at MRI was 18.5 (IQR: 15.5–20.2) years. FALD was graded as “none or mild” in 15 and as “moderate to severe” in the remaining 7 cases. No significant differences in portal, splenic, and hepatic venous blood flow measurements were observed. A trend toward higher blood flow in the right hepatic vein (5.1 [2.4–6.7] vs. 2.4 [1.7–3.1] mL/s, p = 0.067) was seen in patients with moderate to severe FALD. Wall shear stress showed no differences.

Features of portal hypertension (ascites, splenomegaly, or thrombocytopenia) were associated with higher blood flow (3.0 [2.3–4.8] vs. 2.1 [1.6–2.6] mL/s, p = 0.012) and higher wall shear stress in the splenic vein (45 [31–54] vs. 20 [18–28] N/cm², p = 0.016). Correlation analysis showed a relationship between platelet count and left portal vein blood flow (r = 0.544, p = 0.009), platelet count and portal vein wall shear stress (r = −0.434, p = 0.044), gamma-GT levels and superior mesenteric vein blood flow (r = 0.528, p = 0.014), and gamma-GT levels and inferior vena cava wall shear stress (r = 0.493, p = 0.020).

Conclusion: 4D PC flow MRI is suitable to comprehensively assess liver hemodynamics and might help to improve the understanding of Fontan associated liver disease. Further studies with larger cohorts aiming to integrate 4D PC flow MRI in the clinical follow-up of Fontan patients with FALD are needed.

Publication History

Article published online:
28 January 2023