Objective: To quantitatively evaluate the signal intensity of the biliary tract in gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging and to investigate the effect of liver function on the signal intensity of the biliary tract.
Materials and methods: A total of 32 patients with and without chronic liver disease (normal liver group, n = 15; chronic liver disease group, n = 17) were included in this study. All patients were prospectively enrolled for evaluation of known or suspected focal liver lesions. In the chronic liver disease group, the etiologies were chronic hepatitis C virus infection (n = 12) and chronic hepatitis B virus infection (n = 5). The median Child-Pugh score was 5 (range, 5-7). Each patient received the standard dose of Gd-EOB-DTPA (0.025 mmol/kg of body weight). Post-contrast T1-weighted MR images were obtained at 5, 10, 15, 20, 25, and 30 min after administration of Gd-EOB-DTPA. Maximum signal intensities (SIs) of the right and left hepatic ducts, common hepatic duct, and common bile duct were measured. Relative signal intensity was calculated as follows: relative SI = maximum SI(bileduct)/mean SI(muscle). Serum albumin level, serum total bilirubin level, prothrombin time, indocyanine green retention rate at 15 min (ICG-R15), and estimated glomerular filtration rate were entered into regression analysis.
Results: The signal intensity of the bile duct reached a peak 30 min after administration of Gd-EOB-DTPA. The mean relative signal intensity of the right and left hepatic ducts at the peak time point was not significantly different between the two groups, while increase in signal intensity was delayed in the chronic liver disease group. The mean relative signal intensity of the common hepatic duct and that of the common bile duct at the peak time point were significantly different between the two groups (Wilcoxon rank-sum test, P = 0.03, respectively). Stepwise regression analysis revealed that ICG-R15 was a significant predictor of the signal intensity of the bile duct (right and left hepatic ducts, P = 0.04; common hepatic duct, P = 0.008; common bile duct, P = 0.003).
Conclusions: The results of our study demonstrate that the presence of chronic liver disease significantly affects the signal intensity of the bile duct in Gd-EOB-DTPA-enhanced MR imaging. ICG-R15 was only a significant predictor of the signal intensity of the bile duct. The signal intensity of the bile duct may reflect underlying liver function.
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