MANGANESE-METALLOPORPHYRIN (ATN-10) AS A TUMOR-LOCALIZING AGENT - MAGNETIC-RESONANCE-IMAGING AND INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROSCOPY STUDY WITH EXPERIMENTAL BRAIN-TUMORS

OBJECTIVE: We examined whether selective tumor accumulation of a novel manganese-metalloporphyrin (ATN-10) occurs in Fisher rats bearing int racerebral 9L gliomas. METHODS: After intravenous administration of AT N-10, magnetic resonance imaging of brains with tumors or nontumoral v asogenic brain edema was performed. Tissue manganese concentrations we re measured by inductively coupled plasma atomic emission spectroscopy until 48 hours after administration of ATN-10, to evaluate its uptake in tumor, normal brain, and peritumoral brain tissue. RESULTS: In mag netic resonance imaging scans, early enhancement was observed in both tumor tissue and regions of nontumoral vasogenic brain edema at 5 minu tes after ATN-10 administration. However, delayed enhancement was note d only in tumor tissue, at 24 hours after intravenous injection of ATN -10. Comparison of rat brain specimens and 24-hour magnetic resonance imaging scans revealed that only the viable portions of tumors were en hanced with ATN-10; necrotic regions and areas of peritumoral brain ti ssue and nontumoral vasogenic edema were not. Significantly greater up take of ATN-10 was found in tumor samples, compared with normal and pe ritumoral brain tissue, at 24 hours. A high tumor/normal brain tissue ratio (10.4) was achieved at 24 hours. CONCLUSION: ATN-10, a manganese -metalloporphyrin, is a potentially useful tumor-localizing agent that accumulates and is preferentially retained in viable turner tissue.