Dual-Modality Optical/PET Imaging of PARP1 in Glioblastoma

The current study presents [F-18]PARPi-FL as a bimodal fluorescent/positron emission tomography (PET) agent for PARP1 imaging. [F-18]PARPi-FL was obtained by F-19/F-18 isotopic exchange and PET experiments, biodistribution studies, surface fluorescence imaging, and autoradiography carried out in a U87 MG glioblastoma mouse model. [F-18]PARPi-FL showed high tumor uptake in vivo and ex vivo in small xenografts (< 2 mm) with both PET and optical imaging technologies. Uptake of [F-18]PARPi-FL in blocked U87 MG tumors was reduced by 84 % (0.12 +/- 0.02 %injected dose/gram (%ID/g)), showing high specificity of the binding. PET imaging showed accumulation in the tumor (1 h p.i.), which was confirmed by ex vivo phosphor autoradiography. The fluorescent component of [F-18]PARPi-FL enables cellular resolution optical imaging, while the radiolabeled component of [F-18]PARPi-FL allows whole-body deep-tissue imaging of malignant growth.