Hepatocyte-targeted MR contrast agents: contrast enhanced detection of liver cancer in diffusely damaged liver

The performance of hepatocyte-targeted magnetic resonance (MR) contrast agents in the detection of liver tumor was tested in rats with hepatitis. Hepatocyte-targeted MR contrast agents (paramagnetic hepatobiliary complex [manganese-DPDP] and superparamagnetic iron oxide coated with arabinogalactan [SPIO-AG]) were injected into normal rats and rats with carbon tetrachloride-induced hepatitis. Before and after injection of either contrast agent, ex vivo relaxometry (0.94T) or in vivo MR imaging (1.0T) were performed. The obtained liver and tumor T1 and T2 relaxation times, liver and tumor signal-to-noise ratios (SNR), and tumor-liver contrast-to-noise ratios (CNR) of control rats and rats with hepatitis were compared. Both relaxometry and MR imaging showed that MnDPDP and SPIO-AG selectively enhanced liver tissue in controls and in rats with hepatitis to the same degree, and little tumor enhancement was seen in either group. As a result, no significant difference between control rats and rats with hepatitis was observed in the postcontrast tumor-liver CNR. For a MnDPDP-enhanced CNR with spin echo (SE) of 310/15, the results were -10.4+/-3.6 in control rats vs. -11.5+/-1.4 in rats with hepatitis; for a SPIO-AG-enhanced CNR with SE 2000/45 and 2000/90, respectively, the results were 30.7+/-9.2 and 18.7+/-4.7 in control rats vs. 31.9+/-7.1 and 17.7+/-2.4 in rats with hepatitis. These results indicate that hepatocyte-targeted contrast agents effectively enhance liver tissue and enhance liver-tumor image contrast despite hepatocellular dysfunction.