Mouse extrahepatic hepatoma detected on microPET using copper (II)-64 chloride uptake mediated by endogenous mouse copper transporter 1

Purpose: This study was conducted to assess the positron-emitting copper (II)-64 chloride (⁶⁴CuCl₂) as a probe for imaging mouse extrahepatic hepatoma expressing mouse copper transporter 1 (mCtr1) with positron emission tomography (PET). Procedures: Following the intravenous administration of ⁶⁴CuCl₂, athymic mice bearing extrahepatic hepatoma grafts were subjected to whole-body static PET imaging with a Concorde microPET R4 tomograph. Upon completion of the imaging study, immunohistochemistry (IHC) study of mCtr1 was performed with postmortem tissues. Results: The mouse extrahepatic hepatoma grafts were well visualized on static microPET images. Quantitative analysis demonstrated that the tracer concentration in the hepatoma was significantly higher than those in the soft tissue of the right shoulder opposite to the tumor site and the brain (p < 0.001). mCtr1 immunoreactivity in the hepatoma graft was approximately 70% of that in liver, whereas ⁶⁴CuCl₂ concentration in the graft was approximately 11% of the liver concentration. Conclusions: The extrahepatic mouse hepatoma grafts may be visualized by Cu-64 PET, taking advantage of the ⁶⁴CuCl₂ uptake mediated by the functional endogenous mCtr1.