OBJECTIVETo establish a nude mouse model mimicking hepatic metastasis of human colon carcinoma and study its magnetic resonance imaging (MRI) features and the quality of diffusion-weighted images (DWI).

METHODSHuman colon carcinoma SW480 cells were inoculated subcutaneously ((1x10(7)/ml, 0.5 ml) in the costal regions of 2 nude mice, and after successful tumor formation, the generated tumors were harvested and cut into tissue blocks of 1 mm(3). The tissue blocks were subsequently implanted into the liver of 36 nude mice, from which TSE-T1WI, T2WI and EPI-DWI were obtained after tumor growth.

RESULTSThe success rate of intrahepatic tumor implantation was 100% (36/36), and the tumors grown in the liver measured 0.7 to 2 cm in diameter 2 to 6 weeks after implantation. All the tumors were clearly visualized on T1WI and T2WI images, with isointensity on T1WI and hyperintensity on T2WI. Compared with the T2WI, DWI showed conspicuous geometry deformation in 4 mice to cause difficult detection, moderate to slight geometric deformation in 14 mice which remained detectable, and no geometric deformation in 18 mice.

CONCLUSIONThe nude mouse model of hepatic metastasis of SW480 colon cancer cell line, with ideal implantation and tumor growth rate, allows convenient tumor observation on MR T1WI, T2WI and DWI, and the MRI findings of the tumor are well consistent with those by pathological examination, suggesting the validity of this model for molecular imaging research of human colon cancer.