68 Ga-labeled dimeric and trimeric cyclic RGD peptides as potential PET radiotracers for imaging gliomas.

68Ga-labeled cyclic RGD dimers and trimer were evaluated as PET radiotracers. It was found that the linker group had little impact on αvβ3 binding affinity of RGD dimers, which share similar αvβ3 binding affinity with the RGD trimer despite of their different multiplicity. Biodistribution properties of 68Ga radiotracers depend on RGD peptides and radiometal chelates. Among the 68Ga radiotracers evaluated, 68Ga-I2P-RGD2 has the best tumor uptake with good tumor-to-background ratios, and is a good PET radiotracer for imaging gliomas.