Assessing degree of hepatic fibrosis in patients with chronic liver disease using gadoxetic acid-enhanced liver MRI: Preliminary results

Purpose: To assess different degree of hepatic fibrosis using gadoxetic acid-enhanced MRI in patients with chronic liver disease. Materials and Methods: 31 patients with chronic liver disease and 7 healthy subjects were studied using a 1.5 Tesla MRI. Unenhanced and dynamically enhanced images were acquired using gadoxetic-acid contrast (0.025 mmol/kg). Hepatobiliary phase was obtained with a 20 minute time delay. Liver relative enhancement (LRE) values were calculated sampling 1 cm Regions Of Interest (ROI) per segment. According to Metavir score, patients were divided into different groups: Group A = F0-F1 (absent/mild fibrosis), Group B = F2 (moderate fibrosis) and Group C = F3-F4 (advanced fibrosis). Mann-Whitney test with Bonferroni correction ad hoc was adopted to compare LRE values between classes. Receiver Operating Characteristics (ROC) curves were created for prediction of different degree of fibrosis. Results: When comparing LRE mean values a statistical difference between F0-F1 and F3-F4 groups (p=0.008) was observed. A significant report was also observed between moderate and advanced fibrosis (p=0.02). In the comparison between group A and group B no significant difference for LRE mean values (p=0.93) was observed. For prediction of advanced fibrosis, ROC curve showed an Area Under Curve (AUC) of 0.793, with sensitivity of 94.12% and specificity of 57.89% using a threshold LRE value <= 1.0031. For prediction of < F2 stages ROC curve showed an AUC of 0.709, with sensitivity of 63.64% and specificity of 80% using a threshold LRE value > 1.0031. Conclusion: LRE values showed significant difference only between moderate and advanced fibrosis. In patients with chronic liver disease, the assessment of early stages of hepatic fibrosis (mild or moderate fibrosis) is not statistically reliable using gadoxetic acid-enhanced MRI.