Preparation and experimental study of 99Tcm­DTPA­metronidazole for imaging tumor hypoxia

Objective The development of a novel tissue hypoxia imaging agent, 99Tcm­DTPA­metronidazole (MTZ)，has been described here. Methods DTPA­MTZ was synthesized, labeled with 99Tcm by a stannous chloride reduction method. The radiochemical purity was determined by paper chromatography. The biodistribution study and whole body gamma scintigraphic imaging with hepatoma 22 (H22) bearing mice were fulfilled. Results The kit formation has been developed using the synthetic product. 99Tcm­DTPA­MTZ could be prepared by adding pertechnetate into the DTPA­MTZ kit and let react for 10 min in boiling water bath and showed high radiochemical purity of 99%. High tumor/blood ratios (3.43, 6.40 by 1, 2 h) and tumor/muscle ratios (5.24, 7.42 by 1, 2 h) were observed. Hydralazine which affects blood flow and increases hypoxic cell fraction in tumors significantly increased levels of 99Tcm­DTPA­MTZ radioactivity over control levels(P<0.01). Conclusion 99Tcm­DTPA­MTZ is a potential agent to be used for imaging tumor hypoxia in the laboratory or clinic. Key words: Nitroimidazoles; Chemical synthesis; Hypoxic tissue; Animals, laboratory