TUMOR UPTAKE OF (99M)TC MIBI AND (201)TL BY A 9L GLIOSARCOMA BRAIN-TUMOR MODEL IN RATS

There have been several recent case reports of the accumulation of Tc- 99m-MIBI hexakismethoxyisobutylisonitriletechnetium(I), Cardiolite(R) , Sestamibi! in tumors, but no reports of the uptake of this radiophar maccutical in an animal model. To address this question, the biodistri butions of Tc-99m-MIBI and Tl-201 were compared in Fisher rats bearing 9L gliosarcomas. The results showed that, although the absolute uptak e of the tracers by the tumor is relatively low (< 1% ID/g), the tumor are greater than 6:1 because of low uptake by normal brain. The tumor -to-normal brain ratio of Tc-99m-MIBI exceeds that of other currently available Tc-99m radiopharmaceuticals suggesting that Tc-99m-MIBI may be of particular value in the clinical evaluation of brain tumors and that further investigation of this class of compounds as tumor-avid ra diopharmaceuticals is necessary.