Multiple MRI Techniques In Following-up Of Liver Fibrosis Caused By Hepatitis B Virus Infection: A Clinical Study

Purpose:Liver fibrosis caused by Hepatitis B virus(HBV)infection is a worldwide health problem,with its progression as deposition of collagenous fibers and proteoglycan in extracellular-extravascular space,and ultimately cirrhosis.Early diagnosis and adequate treatment can stop or even reverse the progression of liver fibrosis.Liver biopsy is the current gold standard of diagnosing and evaluating therapy of liver fibrosis.However,biopsy is an invasive modality,and repeated biopsies for following up treated liver fibrosis is often rejected by patients.In this project,we aimed to explore an evaluation system with non-invasive,multiple technique-based magnetic resonance imaging(MRI)for long-term following up of liver fibrosis caused by HBV.Material and methodsWe investigated nine MRI parameters of three different MRI techniques,which were collected from 36 fibrosis patients including 11 patients who underwent four serial following up MRI within one and a half years following up after obtaining therapies for repeat biopsy/clinical-approved liver fibrosis/cirrhosis.For each follow-up patient,four consecutive MRI examinations were achieved,including baseline MRI before treatment,and three following-up MRI after treatment with 0.5-year Interval.Different MRI techniques with various parameters included(i)diffusion-weighted imaging(DWI)for assessing apparent diffusion coefficient(ADC)value(b values:200 s/mm2,500 s/mm2,700 s/mm2and 1000 s/mm2);(ii)variable flip angle T1-weighted imaging(T1WI)for assessing T1 value;and(iii)dynamic contrast-enhanced MRI(DCE-MRI)for assessing time to peak(TTP),maximum concentration(MAX conc),area under the curve(AUC)and maximum slope of increase(MSI).These MRI values were correlated to pathology-confirmed liver fibrosis stages,which were subsequently divided into different subgroups.The receiver operating characteristic(ROC)analysis and repeated measurement(RM)analysis of variance were used for statistical analysis.ResultsWe collected a total of 621 values of nine factors from 36 fibrosis patients.1.Results of DWI:ROC analysis showed that ADC value(b=500s/mm2)was the best when differentiating different liver fibrosis subgroups.RM analysis of variance didn’t demonstrate significant differences of ADCs among within F2-3 and F4 groups for parameters of b=500s/mm2,700s/mm2 and 1000s/mm2(p>0.05).2.Results of variable flip angle T1WI:ROC analysis showed that the T1 values were significantly different between the F1-2 VS.F3-4 and F1-3 VS.F4 groups.RM analysis of variance didn’t demonstrate significant differences of T1 value among within F2-3 and F4 groups(p>0.05).3.Results of DCE-MRI:ROC analysis showed that TTP value was the best when used in differentiation between different subgroups.RM analysis of variance of TTP、MAX conc and AUC didn’t demonstrate significant differences.ConclusionsAmong these parameters,the repeatability of the T1 value,TTP and ADC value(b=500s/mm2)were the best for the following-up of liver fibrosis.The results of this study have established ground works for further clinical assessment of treated liver fibrosis/cirrhosis by using non-invasive MR technology.