Diminished liver microperfusion in Fontan patients: A biexponential DWI study

Area of Science:

• Radiology
• Hepatology
• Cardiology

Background:

• Hepatic apparent diffusion coefficients (ADC) decrease in Fontan circulation patients, but the cause (diffusion vs. microperfusion) is unclear.
• Understanding this distinction is crucial for managing potential liver disease in these patients.

Purpose of the Study:

• To differentiate between true molecular diffusion and microperfusion in Fontan circulation livers using intravoxel incoherent motion (IVIM) modeling.
• To compare these parameters with a control group and correlate them with liver function and disease progression.

Main Methods:

• 1.5T MRI with diffusion-weighted imaging (DWI) was used to examine 59 Fontan patients and 19 controls.
• IVIM parameters (Dslow, Dfast, ffast) and ADC were calculated for liver segments.
• Correlations were made with clinical data, follow-up duration, and liver function tests.

Main Results:

• Fontan livers showed significantly reduced microperfusion (Dfast, ffast) compared to controls.
• Molecular diffusion (Dslow) was similar, but ADC was lower in Fontan patients.
• ADC and Dslow decreased with longer follow-up duration post-Fontan, while microperfusion remained stable.

Conclusions:

• Decreasing ADC in Fontan livers primarily reflects reduced hepatic microperfusion, not altered molecular diffusion.
• Long-term, both molecular diffusion and ADC decline post-Fontan, suggesting early intracellular changes preceding fibrosis and cirrhosis.