In Vivo Imaging of Tumor Hypoxia Using 19F MRS of Trifluoromisonidazole

Ellen Ackerstaff¹, Mihai Coman¹, Sean Carlin¹, Sean A. Burke¹, Kristen L. Zakian¹, Khushali Kotedia¹, Joseph O'Donoghue¹, Clifton C. Ling¹, Jason A. Koutcher¹

Tumor hypoxia has been related to treatment response. We used in vivo 19F-MRS/MRSI of Trifluoromisonidazole (TF-MISO) to evaluate tumor hypoxia in two animal tumor models. Intratumoral TF-MISO concentrations were only moderately influenced by tumor growth in both tumor models. The breathing of 21%O₂, 95%O₂/5%CO₂, or 100%O₂ did not significantly influence intratumoral TF-MISO levels in the MCa tumor, whereas in R3327-AT tumors, breathing of 100%O₂ decreased significantly intratumoral TF-MISO levels in tumors below ~600mm³. Our results suggest that hypoxia imaging by ¹⁹F MR of TF-MISO may help to identify tumors that can be successfully reoxygenated and, thus, sensitized for radiation therapy.