Comparison between intravenous and intraarterial contrast injections for dynamic 3D MRI of liver tumors in the VX2 rabbit model

Purpose: To test the hypothesis that catheter-directed intraarterial (IA) contrast agent injection increases tumor enhancement and conspicuity compared to intravenous (IV) injection. Materials and Methods: Eight VX2 liver tumors were grown in five rabbits. After positioning a catheter in the hepatic artery, we performed 3D inversion recovery GRE MRI after IA and IV gadopentetate- dimeglumine contrast injections at doses of 0.04 and 0.1 mmol/kg, respectively. Peak enhancement (signal-to-noise ratio (SNR)) and conspicuity (contrast-to-noise ratio (CNR)) were measured for each acquisition. Results: The peak SNR and CNR were 21.7 ± 5.8 and 17.0 ± 4.8 (mean ± SD) after IA injection, and 16.9 ± 10.2 and 6.2 ± 2.6 after IV injection. The IA CNR was significantly greater than the IV CNR (P < 0.05), with a >60% increase in CNR for each tumor. For six of the eight tumors the IA SNR was greater than the IV SNR, but statistical significance was not achieved due to the small sample size of the study (P = 0.07). Conclusion: We demonstrated the feasibility of using IA injection techniques to improve tumor conspicuity. This strategy could be employed to enhance the detection of small liver tumors or to conserve contrast agent in future MRI-guided transcatheter liver therapies.