Diffusion-weighted MRI versus transient elastography in quantification of liver fibrosis in patients with chronic cholestatic liver diseases

Abstract

Purpose

To evaluate the diagnostic value of diffusion-weighted magnetic resonance imaging (DWMRI) and transient elastography (TE) in quantification of liver fibrosis in patients with chronic cholestatic liver diseases.

Materials and methods

Forty-five patients underwent DWMRI, TE, and liver biopsy for staging of liver fibrosis. Apparent diffusion coefficient (ADC) was calculated for six locations in the liver for combination of five diffusion sensitivity values b = 0, 50, 200, 400 and 800 s/mm². A receiver operating characteristic (ROC) analysis was performed to determine the diagnostic performance of DWMRI and TE. Segmental ADC variations were evaluated by means of coefficient of variation.

Results

The mean ADCs (×10⁻³ mm²/s; b = 0–800 s/mm²) were significantly different at stage F1 versus F ≥ 2 (p < 0.05) and F2 versus F4. However, no significant difference was found between F2 and F3. For prediction of F ≥ 2 and F ≥ 3 areas under the ROC curves were 0.868 and 0.906 for DWMRI, and 0.966 and 0.960 for TE, respectively. The sensitivity and specificity were 90.9% and 89.3% for F ≥ 2 (ADC ≤ 1.65), and 92.3% and 92.1% for F ≥ 3 (ADC ≤ 1.63). Segmental ADC variation was lowest for F4 (CV = 9.54 ± 6.3%).

Conclusion

DWMRI and TE could be used for assessment of liver fibrosis with TE having higher diagnostic accuracy and DWMRI providing insight into liver fibrosis distribution.

Introduction

Chronic cholestatic liver diseases (primary biliary cirrhosis – PBC and primary sclerosing cholangitis – PSC) are important causes of liver cirrhosis and third etiology responsible for liver transplantation. Autoimmune destruction of small and middle sized bile ducts causes progressive liver fibrosis, leading to hepatic dysfunction and cirrhosis [1]. Since hepatic fibrosis is now regarded as a dynamic process with a potential for regression, early detection and staging of liver fibrosis have important clinical impact [2]. Although liver biopsy is still regarded as the standard reference procedure for grading of liver fibrosis, it has several limitations such as hemorrhage risk, interobserver variability and sampling errors [3], [4]. Moreover, it has been demonstrated that liver fibrosis is not uniformly distributed but has rather heterogeneous distribution and sampling only a small portion of tissue during biopsy could lead to incorrect staging [4]. Therefore, there is obvious need for development of noninvasive assessment of liver fibrosis, with possibility of whole liver examination, eliminating sampling errors and reducing biopsy-related risks. Several noninvasive methods for quantification of liver fibrosis have been introduced, such as biochemical scores, transient elastography (TE) and magnetic resonance imaging (MRI) techniques [5], [6]. TE provides immediate evaluation of liver fibrosis severity. To date, there are only a few studies concerning the role of TE in cholestatic liver diseases [7], [8]. Recently, among other MRI techniques, diffusion-weighted magnetic resonance imaging (DWMRI) has emerged as important noninvasive diagnostic tool in the evaluation of liver fibrosis [9]. DWMRI allows global liver examination with insight into distribution of liver fibrosis and detection of the most affected liver segments. At present, there are several reports regarding the use of DWMRI for the detection of liver fibrosis severity [10], [11], [12]. However, these reports were mostly focused on patients with chronic viral hepatitis. Even though the end stage of all chronic liver diseases is cirrhosis, there are differences in the pathogenesis, fibrosis pattern and rate of progression between chronic viral liver diseases and chronic cholestatic diseases. Hence, thin perilobular bands and perivascular cuffing, as a form of diffuse fibrosis, appear most commonly in cholestatic diseases [13]. To our knowledge, there are no published data on the diagnostic accuracy of DWMRI in the evaluation of patients with PBC and PSC. Therefore, the purpose of the current study was to determine the diagnostic value of DWMRI in comparison with TE for quantification of liver fibrosis in patients with chronic cholestatic diseases with reference to liver biopsy as the gold standard.