Objective To assess the clinical feasibility of diagnosing and staging liver fibrosis by apparent diffusion coefficient （ADC）. Methods Totally

43 patients （mean age 29.3 years） with chronic hepatitis by liver biopsy and 7 healthy controls （mean age 39.9 years） underwent liver diffusion weighted imaging （DWI） with four b values: 0

200

500

and 1000 s/mm2 respectively. The liver fibrosis was staged according to Ishak fibrosis stage. The ADC value of liver fibrosis patients and healthy controls was compared. The correlation of ADC value and liver fibrosis staging was analyzed. Result The histological staging showed 8 stage 1 patients

10 stage 2 patients

6 stage 3 patients

9 stage 4 patients

8 stage 5 patients and 2 stage 6 patients. The mean ADC value of liver fibrosis patients was significantly lower than that of healthy controls except for stage 1 group （P < 0.05）. There was a negative correlation between liver fibrosis staging and ADC value （r = -0.697 with b=500 s/mm2

P < 0.01）. Receiver operating characteristic （ROC） curve of ADC value of advanced liver fibrosis （Ishak stage F3 and higher） showed that area under curve = 0.913

0.825

and 0.794 with b = 500

1000

and 200 s/mm2

respectively （95% confidence interval: 83.6%-99.0%

70.7%-94.3%

66.5%- 92.4%; P < 0.05）. When b value was 500 s/mm2

the sensitivity （84%） and specificity （80%） of DWI for diagnosis of advanced liver fibrosis were the highest. Conclusion DWI is proved to be a useful clinical tool in the quantitative evaluation of liver fibrosis and in the prediction of the process of liver fibrosis with the recommendable b value （500 s/mm2）.