Determining Hypoxic Fraction in a Rat Glioma by Uptake of Radiolabeled Fluoromisonidazole

Abstract Rasey, J.S., Casciari, J.J., Hofstrand, P.D., Muzi, M., Graham, M.M. and Chin, L.K. Determining the Hypoxic Fraction in a Rat Glioma by Uptake of Radiolabeled Fluoromisonidazole. The usefulness of radiolabeled nitroimidazoles for measuring hypoxia will be clarified by defining the relationship between tracer uptake and radiobiologically hypoxic fraction. We determined the radiobiologically hypoxic fraction from radiation response data in 36B10 rat gliomas using the paired cell survival curve technique and compared the values to the radiobiologically hypoxic fraction inferred from mathematical modeling of time–activity data acquired by PET imaging of [18F]FMISO uptake. Rats breathed either air or 10% oxygen during imaging, and timed blood samples were taken. The uptake of [3H]FMISO by 36B10 cells in vitro provided cellular binding characteristics of this radiopharmaceutical as a function of oxygen concentration. The radiobiologically hypoxic fraction determined for tumors in air-breathing rats usi...