Liver Fibrosis in Chronic Hepatitis C Virus Infection: Differentiating Minimal from Intermediate Fibrosis with Perfusion CT

Purpose: To prospectively assess the utility of perfusion computed tomography (CT) for differentiating minimal from intermediate fibrosis in treatment-naive patients with chronic hepatitis C virus (HCV) infection. Materials and Methods: This study was approved by the Institutional Review Board, and informed consent was obtained. Fifty-two patients with treatment-naive HCV infection underwent perfusion CT and percutaneous liver biopsy on the same day. Portal vein, arterial, and total liver perfusion; mean transit time; and distribution volumes for the right and left liver lobes were measured. Liver samples were scored for fibrosis, and fibrosis area was determined. Differences in quantitative perfusion parameters between patients with minimal fibrosis (score of F1) and those with intermediate fibrosis (score of F2 or F3) were tested. Results: In patients with intermediate fibrosis (F2 and F3) compared with those with minimal fibrosis (F1), the portal venous perfusion (87 mL . min(-1) . 100 mL(-1) +/- 27 [standard deviation] vs 138 mL . min(-1) . 100 mL(-1) +/- 112, P = .042) and total liver perfusion (107 mL . min(-1) . 100 mL(-1) +/- 31 vs 169 mL . min(-1) . 100 mL(-1) +/- 137, P = .02) were significantly decreased, and the mean transit time was significantly increased (16 seconds +/- 4 vs 13 seconds +/- 5, P = .025). At multivariate analysis, only the mean transit time was an independent factor (odds ratio, 1.18; 95% confidence interval: 1.02, 1.37; P = .030). Receiver operating characteristic curve analysis showed that a mean transit time threshold of 13.4 seconds allowed discrimination between minimal and intermediate fibrosis with a sensitivity of 71% and a specificity of 65%. Conclusion: The results of this study show that perfusion changes occur early during fibrosis in chronic HCV infection and can be detected with perfusion CT. Perfusion CT may help to discriminate minimal from intermediate fibrosis. Mean transit time appears to be the most promising perfusion parameter for differentiating between fibrosis stages, although the large amount of overlap in the measured parameters limits the clinical utility of this test at present. (C) RSNA, 2010