Magnetic Resonance Imaging to Evaluate Hepatic Fibrosis

• Main Authors: Wen-Pei Wu, 吳文沛
• Other Authors: Ran-Chou Chen
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/76q27s

博士 === 國立陽明大學 === 生物醫學影像暨放射科學系 === 106 === The prevalence of chronic hepatitis B (HBV) and chronic hepatitis C (HCV) in Taiwan is high, and about 10 to 20% of chronic liver disease would progress to liver cirrhosis and hepatocellular carcinoma. In patients with the early stage of liver fibrosis, using anti-viral treatment is confirmed effective to the progress of liver cirrhosis. Therefore, it’s important for diagnosis of early stage of liver fibrosis. Nowadays, the golden diagnosis of liver cirrhosis depends on percutaneous liver biopsy. It’s an invasive procedure and has high risk for poor liver function, not well accepted by the patients. Several non-invasive methods developed to diagnosis hepatic fibrosis. Elasticity generates images based on the stiffness or hardness of a lesion and correlates to a physical examination. In the previous literature, MR Elastography has been confirmed that it is highly correlated with the fibrosis stage of liver cirrhosis, i.e., the higher the degree of fibrosis, the worse hardness or elasticity of the liver. It is the highest efficient known study among non-invasive examinations nowadays. Gd-EOB-DTPA-enhanced MR imaging for liver is considered as the most effective diagnosis modality for detecting liver tumor. Due to its uptake and excretion by the hepatocyte, the enhancement of liver parenchyma and biliary excretion correlated with liver function. In the series of my studies, the objectives are mainly focusing on using MR Elastography for non-invasive examination of hepatic fibrosis. The results of histopathologic analysis were used as the reference standard. The liver stiffness measurement by MR Elastography were also compared with serum biomarkers such as APRI, ultrasound-based elastography such as ARFI elastography, and Gd-EOB-DTPA-enhanced MR imaging. 1 The diagnostic performance of MR Elastography: To compare the accuracy of MRE with that of APRI for estimating the stage of hepatic fibrosis in patients with HBV or HCV. We retrospectively enrolled 160 patients with chronic hepatitis and 25 healthy living liver donors. In this study, MRE had a significantly greater area under the ROC curve than APRI score for discriminating among METAVIR stages F2-F4. Using a cutoff value of 2.80 kPa, MRE had a sensitivity of 94.4% and a specificity of 97.8% for detecting significant fibrosis (>= F2). There were no significant differences in fibrosis stage between patients with HBV and those with HCV infection. For >= F2, the cutoffs were 2.47 kPa (100% sensitivity), 2.80 kP (maximum sum of sensitivity and specificity), and 3.70 kPa (100% specificity). 2 Prospective comparison of the diagnostic accuracy of MRE with that of ARFI Elastography for staging hepatic fibrosis. We prospectively enrolled 77 patients who were scheduled to undergo hepatectomy for hepatocellular carcinoma. Pre-operative MRE and ARFI elastography examinations were performed on the same day. In this study, correlation of MRE was excellent and correlation of ARFI elastography was good with fibrosis stage. MRE had better diagnostic performance than ARFI elastography in estimating substantial fibrosis (F2), severe fibrosis (F3) and cirrhosis (F4). ROC analysis revealed that MRE discriminated advanced stages of fibrosis (F ≥ 2) well in patients with hepatocellular carcinoma at a cutoff value of 3.0 kPa with an AUROC value of 0.93, and ARFI elastography did so at a cutoff value of 1.77 m/s with an AUROC value of 0.81 for predicting advanced stages of fibrosis (F ≥ 2). In conclusion, MRE is a more accurate imaging modality than ARFI elastography in estimating advanced stages of fibrosis and cirrhosis. 3 Comparison of the efficacy of Gd-EOB-DTPA-enhanced MR imaging and MR Elastography in the estimation of hepatic fibrosis stages. This retrospective study included 104 patients (87 men and 17 women; mean age, 60.6 ± 10.6 years) with chronic liver disease who underwent both Gd-EOB-DTPA-enhanced MRI and MRE. The relative enhancement (RE) ratio of the liver parenchyma and the contrast enhancement index (CEI) were calculated as (SI postliver - SI preliver )/SI preliver and SI post /SI pre , respectively, where SI post and SI pre were the liver-to-muscle signal intensity ratios on the hepatobiliary phase images and noncontrast-enhanced images, respectively. The liver stiffness values were measured using MRE stiffness maps. In this study, the distribution of fibrosis stages was as follows: F0, n=3 (2.9%); F1, n=12 (11.5%); F2, n=17 (16.3%); F3, n=26 (25.0%); and F4, n=46 (44.2%). MRE, RE ratios, and CEI values correlated significantly with hepatic fibrosis (rs =.79, -0.35, -0.25, respectively, P<.05). MRE showed a significantly higher diagnostic performance than did RE ratios and CEI values for each fibrosis stage, except while distinguishing the F1 fibrosis stage (CEI, P=.15). A cutoff value of RE ratio=0.89 can be used to identify patients with significant hepatic fibrosis, with positive predictive value, sensitivity, specificity, and negative predictive value of 93.2%, 61.8%, 73.3%, and 24.4%, respectively. Our studies indicate that MRE is an accurate, reliable non-invasive technique for estimating hepatic fibrosis stage. Since MRE is more accurate than ARFI or other non-invasive diagnostic examinations, it might be possible to become one of the first-line assessment for the severity of hepatic fibrosis. MRE may be preferable if diagnosing the significant fibrosis (F2 or greater) is needed.