Liver fibrosis in chronic hepatitis C virus infection: differentiating minimal from intermediate fibrosis with perfusion CT

Dynamic contrast-enhanced magnetic resonance imaging with Gd-EOB-DTPA for the evaluation of liver fibrosis in chronic hepatitis patients

OBJECTIVES

To develop a non-invasive MRI method for evaluation of liver fibrosis, with histological analysis as the reference standard.

METHODS

The study protocol was approved by the Institutional Review Board for Human Studies of our hospital, and written informed consent was obtained from all subjects. Seventy-nine subjects who received dynamic contrast-enhanced MRI (DCE-MRI) with Gd-EOB-DTPA were divided into three subgroups according to Metavir score: no fibrosis (n = 30), mild fibrosis (n = 34), and advanced fibrosis (n = 15). The DCE-MRI parameters were measured using two models: (1) dual-input single-compartment model for arterial blood flow (F (a)), portal venous blood flow, total liver blood flow, arterial fraction (ART), distribution volume, and mean transit time; and (2) curve analysis model for Peak, Slope, and AUC. Statistical analysis was performed with Student's t-test and the nonparametric Kruskal-Wallis test.

RESULTS

Slope and AUC were two best perfusion parameters to predict the severity of liver fibrosis (>F2 vs. ≦F2). Four significantly different variables were found between non-fibrotic versus mild-fibrotic subgroups: F (a), ART, Slope, and AUC; the best predictor for mild fibrosis was F (a) (AUROC:0.701).

CONCLUSIONS

DCE-MRI with Gd-EOB-DTPA is a noninvasive imaging, by which multiple perfusion parameters can be measured to evaluate the severity of liver fibrosis.

CT hepatic perfusion measurement: comparison of three analytic methods

OBJECTIVES

To compare the efficacy of three analytic methods, maximum slope (MS), dual-input single-compartment model (CM) and deconvolution (DC), for CT measurements of hepatic perfusion and assess the effects of extra-hepatic systemic factors.

MATERIALS AND METHODS

Eighty-eight patients who were suspected of having metastatic liver tumors underwent hepatic CT perfusion. The scans were performed at the hepatic hilum 7-77 s after administration of contrast material. Hepatic arterial and portal perfusions (HAP and HPP, ml/min/100 ml) and arterial perfusion fraction (APF, %) were calculated with the three methods, followed by correlation assessment. Partial correlation analysis was used to assess the effects on hepatic perfusion values by various factors such as age, sex, risk of cardiovascular diseases, arrival time of contrast material at abdominal aorta, transit time from abdominal aorta to hepatic parenchyma, and liver dysfunction.

RESULTS

Mean HAP of MS was significantly higher than DC. HPP of CM was significantly higher than MS and CM, and HPP of MS was significantly higher than DC. There was no significant difference in APF. HAP and APF showed significant and moderate correlations among the methods. HPP showed significant and moderate correlations between CM and DC, and poor correlation between MS and CM or DC. All methods showed weak correlations between HAP or APF and age or sex. Finally, MS showed weak correlations between HAP or HPP and arrival time or cardiovascular risks.

CONCLUSIONS

Hepatic perfusion values arrived at with the three methods are not interchangeable. CM and DC are less susceptible to extra-hepatic systemic factors.

Chronic liver disease: systemic and splanchnic venous flow mapping with optimized cine phase-contrast MR imaging validated in a phantom model and prospectively evaluated in patients

PURPOSE

To validate magnetic resonance (MR) imaging cine phase-contrast blood flow mapping in vitro and in patients with chronic liver disease, with or without portal hypertension, and to assess the accuracy of azygos, splanchnic, and systemic blood flow measured with MR imaging in the detection of high-risk esophageal varices and compare these measurements with endoscopic evaluation, the reference standard.

MATERIALS AND METHODS

The local ethics committee approved this study. Patients gave written informed consent. Two phantoms were used to validate the MR imaging phase-contrast flow sequence. Patients with liver cirrhosis (n = 59), chronic liver disease without cirrhosis (n = 12), and nodular regenerative hyperplasia (NRH) (n = 11), and healthy control subjects with no liver disease (n = 25) were included. The patients underwent upper digestive system endoscopy. Mean abdominal aorta, portal venous, and azygos blood flow was measured on MR images, which were reviewed by two blinded observers to determine the presence and grade of esophageal varices. The reproducibility and intra- and interobserver variability of the blood flow measurements were assessed with intraclass correlation coefficients (ICCs). The performance of the MR blood flow measurements in staging high-risk varices was determined with receiver operating characteristic curve analysis. The correlation between MR visual analysis and endoscopic grading was assessed by using κ statistics.

RESULTS

MR flow rate measurements had excellent correlations with actual flow values in vitro (ICC > 0.990 for phantoms 1 and 2). Mean aortic flow was significantly higher in patients with cirrhosis than in control subjects (P < .001). Mean azygos flow was significantly higher in patients with cirrhosis than in patients with chronic liver disease without cirrhosis (P = .005) and control subjects (P < .001). Low intra- and interobserver variability (ICC > 0.990 for each blood flow type) and high reproducibility (ICC > 0.850 for each blood flow type) were demonstrated. The optimal cutoff mean azygos flow value was 2.3 mL/sec for varices with grades of 2 or higher.

CONCLUSION

MR imaging azygos flow measurement appears to be a promising technique for detecting high-risk esophageal varices in patients with portal hypertension.