Quantitative PET Imaging of Tumor Integrin avb3 Expression with 18F-FRGD2

The development of noninvasive methods to visualize and quan-tify integrin avb3 expression in vivo appears to be crucial for the success of antiangiogenic therapy based on integrin antago-nism. Precise documentation of integrin receptor levels will allow appropriate selection of patients whowill most likely benefit from an antiintegrin treatment regimen. Imaging can also be used to provide an optimal dosage and time course for treatment based on receptor occupancy studies. In addition, imaging integrin ex-pression will be important to evaluate antiintegrin treatment effi-cacy and to develop new therapeutic drugs with favorable tumor targeting and in vivo kinetics. We labeled the dimeric RGD pep-tide E[c(RGDyK)]2 with 18F and evaluated its tumor-targeting ef-ficacyandpharmacokineticsof 18F-FB–E[c(RGDyK)]2 (18F-FRGD2). Methods: E[c(RGDyK)]2 was labeled with 18F by conjugation cou-pling with N-succinimidyl-4-18F-fluorobenzoate (18F-SFB) under