Objective: This study was designed to investigate the value of nano-MRI compared with the routine gadolinium diethylene triaminepenta acetate contrast MRI of metastatic hepatocellular carcinoma.
Methods: Livers of healthy BALB/c nude mice were implanted with cells of hepatocellular carcinoma - HepG2 and SMMC77219, respectively. Small interfering RNA targeting was accomplished against one of the three hepatocellular carcinoma-survivin gene sequences. Nanometer grade particles especially the superparamagnetic iron oxide nanoparticle superparamagnetic iron oxide nanoparticles Resovist was complexed with polylysine and siRNA designed specifically to create an enhanced contrast agent with superparamagnetic iron oxide nanoparticles. Both hepatocellular carcinoma -HepG2 and SMMC7721 groups were scanned at 1.5 T MRI without any contrast MRI, gadolinium diethylene triaminepenta acetate contrast medium, and the specific enhanced contrast agent with superparamagnetic iron oxide nanoparticles by injecting the contrast media via tail vein. All mice were scanned with T2 weighted imaging 24 h post-injection, to observe the effect of the specific contrast medium with superparamagnetic iron oxide nanoparticles. Subsequently, all the mice were sacrificed to extract the livers.
Results: Tumor detection rate 24 h post-injection, corresponding to the specific contrast agent with superparamagnetic iron oxide nanoparticles showed a significant difference compared with the gadolinium diethylene triaminepenta acetate contrast agent. The livers still showed remarkably low signal change within the signal enhanced region of T2WI compared with instant imaging using the specific SPIO.
Conclusion: Nanometer grade particles can be stably transfected into tumor cells to facilitate detection of human hepatocellular carcinoma xenografts in nude mice using small interfering RNA. The strong paramagnetic effect observed with the high valence iron in T2WI improves the detection rate of micronodular (<5 mm) HCC with MRI.