A method of three-dimensional branching geometry to differentiate the intrahepatic vascular type in early-stage liver fibrosis using X-ray phase-contrast CT

Abstract

Purpose: Differentiating the intrahepatic vascular type is essential for the early diagnosis of liver fibrosis. X-ray phase-contrast computed tomography (PCCT) is a label-free, high-resolution imaging modality for imaging vascular networks in a whole liver lobe. This study explores the use of three-dimensional (3D) branching geometry to differentiate between the hepatic vein (HV) and portal vein (PV) in early-stage liver fibrosis with PCCT.

Method: Bile duct ligation surgery was conducted in mice to induce early-stage liver fibrosis. The individual liver lobes of mice were imaged using PCCT, and morphological characteristics, including vascular diameter, cross-sectional area, eccentricity, branch angle, bifurcation index, area ratio and junction exponent, were investigated in 3D modality. These characteristics were used to differentiate the HV from the PV, and their performance was evaluated through receiver operating characteristic (ROC) curve analysis.

Results: PCCT revealed a 3D vascular structure of the liver lobes. For intact lobes, the differentiation method between the HV and PV using the junction exponent had an AUC of 0.99 (95% CI: 0.98-1.00). Moreover, the AUCs of the junction exponent for 15, 10, and 5 branches in dissected lobes for differentiation were 0.98 (95% CI: 0.94-1.00), 0.86 (95% CI: 0.73-0.99) and 0.82 (95% CI: 0.67-0.97), respectively.

Conclusion: The method of 3D branching geometry using the junction exponent could differentiate the HV from PV in early-stage liver fibrosis via the PCCT, which provides the foundation for further analysis of liver fibrosis.

Keywords: Branching geometry; Differentiation method; Hepatic vasculature; Liver fibrosis; X-ray phase-contrast computed tomography.