DIFFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING FOR THE STAGING OF LIVER FIBROSIS: A PRELIMINARY STUDY IN PATIENTS WITH CHRONIC LIVER DISEASE

Background and aim: Liver fibrosis (LF) is often a possible evolution of chronic liver disease, with a significant risk of progression into cirrhosis. This study was designed to establish whether the measurement of apparent diffusion coefficients (ADC) is clinically accurate in diagnosis in a selected series of pts with chronic liver disease (CLD). Material and methods:The study was carried out in the period 2008–2012. We recruited 42 pts with CLD (mean age 53 yrs-range 18–76, 26 M-16 F). Patients were examined using diffusion-weighted magnetic resonance imaging (MRI) with single shot echo-planar technique and with a 1.5 tesla-magnet equipped. This test measures the diffusion of water molecules in the fibrotic liver tissue through the calculation of the ADC that is extracted by the following formula: ADC = ln(S0/S1)/b, b=500. For each pt the hepatic fibrosis was evaluated in accordance with the METAVIR score (F0-F4) after liver biopsy. Patients were stratified into 3 groups (1, 2, 3) according to the different degree of fibrosis, and the ADC was compared with U-test of Mann-Whitney (U-test). We also evaluated the presence of advanced fibrosis (group 3) or clinically significant fibrosis (groups 2–3) with the use of the analysis Receiver-Operating-Characteristic (ROC). Results:We found a significant difference between group 1 (F0-F1) and group 3 (F3-F4) with p=0.0028, and between group 2 (F2) and group 3, with p=0.026. We did not find a significant difference between the ADC values in group 1 and group 2. More widely, a significant difference (p=0.001) was observed comparing pts with fibrosis>F2 and pts with fibrosis≤F2. Area under the curve (AUC) predicted the membership in the group 3 with a value=0.82 (95% CI: 0.657–0.928; cut-off: 1.4154). The sensitivity and specificity were 73.7% and 82.3%, respectively. However, in predicting the membership of clinically significant fibrosis (groups 2–3), we obtained AUC=0.765 (95% CI: 0.595–0.890; cut-off: 1.4154). The sensitivity was reduced to 61.5% and the specificity was 90%. Conclusions:Our study showed a correlation between reduction of ADC and the increasing in liver fibrosis degree. The ADC has appeared useful in staging liver fibrosis in pts with CLD, in particular to distinguish the later stages of fibrosis from early and intermediate stages.