Aim: To elucidate the MRI mechanisms of manganese oxide-coated carbohydration nanosphere (Mn@CNS) for active targeting in hepatobiliary tumors. Materials & methods: The cytotoxicity, internalization pathway, metabolism and excretion pathway of Mn@CNS were assessed by several cell types. The MRI of Mn@CNS was verified via rat models bearing hepatobiliary tumors. Results: Mn@CNS showed no obvious cytotoxicity. Mice macrophage and hepatocellular Mn content significantly differed between pre- and post-uptake levels (p