A study of diagnostic performance of MR elastography in liver fibrosis with chronic hepatitis B

Objective To explore the diagnostic value of MR elastography and diffusion-weighted imaging in patients with liver fibrosis in the context of chronic hepatitis B. Methods Twenty-four patients with chronic hepatitis B, whose course of liver disease was more than 6 months and hepatitis B surface antigen was positive, were prospectively enrolled in the First Affiliated Hospital of Soochow University from July to December 2017. All of the patients underwent abdominal transient elastography (TE), routine MRI, magnetic resonance elastography (MRE) and DWI examination, TE and MRI were performed within one week. TE liver stiffness was measured, the MRE liver stiffness and ADC value were measured on MR imagings. All patients were divided into three groups: mild and non fibrosis (F0 to 1), significant fibrosis(F2 to 3) and cirrhosis (F4), according to the recommended standard of FibroTouch. Correlation between TE liver stiffness, MRE liver stiffness and ADC values were identified by using Spearman correlation test. The difference of the MRE liver stiffness and ADC value among the three groups was tested using independent sample t test. The overall predictive ability of MRE and DWI in assessment of liver fibrosis and cirrhosis was analyzed by constructing ROC curve. Results TE and MRI were successfully performed in all subjects, and the image quality was good. The MRE liver stiffness in mild and non fibrosis, significant fibrosis and cirrhosis was (2.32±0.31),(3.43±1.05),(4.77±0.68) kPa with statistically significant difference (F=61.690, P<0.01). The ADC values in three groups were (1.31±0.14)×10-3, (1.23±0.15)×10-3,(1.22±0.12)×10-3mm2/s without significant difference (F=1.074,P=0.360). The TE liver stiffness in three groups was (5.61±1.05), (9.56±0.57), (17.25±3.55)kPa, respectively, there was significant correlation between the MRE liver stiffness and the TE liver stiffness(t=0.858, P<0.01), but no significant correlation between the TE liver stiffness and the ADC value was found (r=-0.326,P=0.120). The area under ROC of MRE liver stiffness in diagnosing liver fibrosis grade (≥ F2 and F4) was 0.96 and 1.00 respectively, while the AUC of ADC value was less than 0.70, which were 0.67 and 0.62 respectively. Conclusion MRE is a non-invasive promising tool for assessing liver fibrosis with chronic hepatitis B, while DWI has limited role. Key words: Liver fibrosis; Magnetic resonance elastography; Diffusion weighted imaging