AUTORADIOGRAPHY AND RADIOSCINTIGRAPHY OF TECHNETIUM-99M-SESTAMIBI IN C-NEU TRANSGENIC MICE

Intratumor distribution patterns of Tc-99m-sestamibi and (14)C2-deoxy- D-glucose were compared in the c-neu OncoMouse(TM), a transgenic mouse that spontaneously develops breast tumors. Methods: Thirty or 60 min after intravenous injection of 5 mu Ci (14)C2-deoxy-D-glucose and 3 mC i Tc-99m-sestamibi into mice (n = 3 per time point) bearing mammary tu mors (0.3-1.5 cm), the animals were analyzed for organ and tumor distr ibution using dual-label, whole-body autoradiography. The retention pa tterns of the two compounds were related to tumor morphology and viabi lity, based on H&E-stained adjacent sections. For imaging studies, the transgenic mice (n = 9) were anesthetized with pentobarbital, injecte d intravenously with 5-20 mCi Tc-99m-sestamibi and imaged for 60 min u sing a gamma camera equipped with a I-mm pinhole collimator. Results: All positively stained tumors retained both agents, with a mean Tc-99m -sestamibi tumor retention of 0.38% +/- 0.2% ID/g at 30 min compared t o 4.18% +/- 0.62% ID/g far C-14-2-deoxy-D-glucose. Tumor retention of the agents remained the same at 60 min, and neither compound localized within necrotic or cystic regions of the neoplasms. Repeat imaging at 2-8-day intervals indicated a predicted sensitivity to detect a 30% d ifference in tumor retention of a test versus reference compound in pr eclinical screening. Conclusion: The c-neu OncoMouse(TM) is a useful m odel for in vivo imaging and provides a spontaneous tumor model for pr eclinical screening of breast tumor imaging agents.