Heterogeneous development of liver fibrosis in chronic hepatitis C patients; assessment by extracellular volume fraction map generated from routine clinical CT data.

Objectives: To clarify the heterogeneous development of liver fibrosis in patients with chronic hepatitis C (CHC) using extracellular volume fraction (ECV) map obtained from routine clinical CT data.

Methods: Between November 2012 and July 2020, patients with CHC were retrospectively recruited who had undergone four-phase CT and MR elastography (MRE) within one year. Patients were divided into 4 grades to represent different cirrhotic/fibrotic stage, using two different methods; one based on liver stiffness measured by MRE (MRE model), and the other by mALBI grades (mALBI model). Liver was anatomically divided into 16 sections, namely peripheral and central areas of each segment. ECV map was generated according to the previously reported method, and ECV was measured for the 16 sections. Estimated pathological fibrosis grade was assigned for each section based on the previously reported data.

Results: There were 150 patients available. In each anatomical section, ECV significantly increases as cirrhotic /fibrotic stage progresses. The peripheral areas of segments 4,5 and 8 were the earliest to show F2 or F3-equivalent ECV (p < 0.05), followed by central areas or other segments. The central areas of segments 6 and 7 were the last to be involved by fibrosis both in MRE and mALBI models, finally almost all sections showing F4-equivalent ECV at the end stage fibrosis.

Conclusion: Fibrosis starts at the peripheral areas of segments 4, 5, and 8, and spreads towards other parts of the liver, with the central areas of segments 6 and 7 being the last, in patients with CHC.