Manganese-metalloporphyrin (ATN-10) as a tumor-localizing agent: magnetic resonance imaging and inductively coupled plasma atomic emission spectroscopy study with experimental brain tumors.

Abstract

We examined whether selective tumor accumulation of a novel manganese-metalloporphyrin (ATN-10) occurs in Fisher rats bearing intracerebral 9L gliomas. After intravenous administration of ATN-10, magnetic resonance imaging of brains with tumors or nontumoral vasogenic brain edema was performed. Tissue manganese concentrations were 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. In magnetic resonance imaging scans, early enhancement was observed in both tumor tissue and regions of nontumoral vasogenic brain edema at 5 minutes after ATN-10 administration. However, delayed enhancement was noted 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 enhanced with ATN-10; necrotic regions and areas of peritumoral brain tissue and nontumoral vasogenic edema were not. Significantly greater uptake of ATN-10 was found in tumor samples, compared with normal and peritumoral brain tissue, at 24 hours. A high tumor/normal brain tissue ratio (10.4) was achieved at 24 hours. ATN-10, a manganese-metalloporphyrin, is a potentially useful tumor-localizing agent that accumulates and is preferentially retained in viable tumor tissue.