Prediction of tumor radiosensitivity by hexafluoromisonidazole retention monitored by [1H]/[19F] magnetic resonance spectroscopy.

Hexafluoromisonidazole (CCI-103F) is a hypoxic cell label that can be measured by in vivo [1H]/[19F] magnetic resonance spectroscopy (MRS). The retention of CCI-103F in SCCVII tumors was found to be correlated with tumor size, with larger tumors retaining more label. Such a correlation was anticipated, as larger SCCVII tumors have larger hypoxic fractions. A significant but less strong correlation was also found between CCI-103F retention and the fraction of tumor cells surviving after 10 Gy irradiation, with tumors that retained larger amounts of CCI-103F having higher surviving fractions. These results indicated that non-invasive MRS measurement of CCI-103F retention could predict radiosensitivity in SCCVII tumors. The lack of a strong correlation between CCI-103F retention and radiosensitivity, however, indicated that hypoxic fraction was not the only factor influencing radiosensitivity in these tumors.