Pre-Hepatectomy Assessment of Bile Transporter Expression by Gadoxetic Acid-Enhanced MRI in a Rat Model of Liver Cirrhosis

Abstract

Background: Gadoxetic acid is a liver-specific intravenous T1 magnetic resonance (MR) contrast agent that is excreted via the hepatobiliary system. We hypothesize that hepatocyte expressions of bile transporters (OATP1 and MRP2) correlate with dynamic profile of Gadoxetic acid enhanced (GE)-MR imaging (MRI). Methods: Two groups of rats, control (n = 6) and cirrhosis (n = 12), received gadoxetic acid enhanced MRI followed by 70% hepatectomy. The change in MR signal intensity from the baseline before the contrast injection (SI) was analyzed every minute for 30min. Dynamic signal intensity retention ratio (DSR) was defined as the mean SI of the third 10-minmin period divided by the first 10-minmin period. Real-time PCR was utilized to quantify mRNA expressions. Results: Compared to the control, cirrhosis group demonstrated lower mRNA levels of OATP1 (0.038 +/- 0.020vs. 0.232 +/- 0.0979; p = 0.004), MRP2 (0.201 +/- 0.084vs. 0.7567 +/- 0.254; p = 0.002), and OATP1/MRP2 mRNA ratio (0.193 +/- 0.065vs. 0.342 +/- 0.206; p = 0.032). DSR was higher in the cirrhosis group (0.678 +/- 0.554vs -0.125 +/- 0.839; p = 0.033). In the cirrhosis group, there was an inverse correlation between the ratios of OATP1/MRP2 mRNA and DSR (R = -0.709, p = 0.01). Conclusion: Bile transporters OATP1/MRP2 mRNA expression ratio in rat liver tissue decreased with DMN-induced liver injury. The expressions of bile transporters correlated with GE-MRI DSR. The GE-MRI DSR has potential utility in qualifying OATP1/MRP2 mRNA expression.