The Efficiency of Fractional Anisotropy, Apparent Diffusion Coefficient, and Contrast Enhancement Index in Liver Fibrosis Staging

Abstract

Objectives: Even though magnetic resonance imaging has been described as the most effective imaging method for the diagnosis of liver fibrosis, an accepted magnetic resonance imaging (MRI) technique is yet to be defined. The aim of this study is to determine the efficiency of MRI in the staging of liver fibrosis. Methods: Patients with chronic hepatitis B infection and had upper abdominal MRI with hepatocyte specific contrast agent were evaluated. Twenty-nine patients that had undergone liver biopsy were included in the study. ADC, FA, and signal intensity values of liver parenchyma were measured by two observers and contrast enhancement index (CEI) was calculated as well. Patients were grouped as early (A) and late fibrosis(B) according to Ishak grading system and then the correlations between the stage and MRI findings were analysed. The intraclass correlation coefficient was used to analyze the inter-rater agreements. ADC, FA, and CEI were compared with Student t-test between early and late fibrosis groups. Pearson's correlation was used to assess the correlation between ADC and FA values. Spearman correlation was used to evaluate the relationship between pathologic fibrosis grade and MRI parameters that were measured. Results: Twenty-two patients were staged as 1 and 2 (group A), seven patients were staged as 3 and above fibrosis(group B). Statistically, there was a strong, negative correlation between the FA values and the degree of fibrosis (r=-0.582, p=0.001). There was no correlation between the CEI and hepatocyte activity index (r=-0.88, p=0.655) and degree of fibrosis (r=0.0001, p=0.997). In terms of FA values, there was a statistically significant difference between two groups (group A=0.429 +/- 0.06, group B=0.349 +/- 0.06) (p=0.004). Conclusion: Correlation of FA values with fibrosis stage and significant difference in FA values between early-late stage fibrosis patients shows that diffusion tensor imaging can be a promising technique in the staging and follow-up of liver fibrosis.