A Facile Radiolabeling of [18F]FDPA via Spirocyclic Iodonium Ylides: Preliminary PET Imaging Studies in Preclinical Models of Neuroinflammation.

A suitable TSPO PET ligand may visualize and quantify neuroinflammation in a living brain. Herein we report a 18F-ligand, [18F]2 ([18F]FDPA), is radiolabeled in high yield and high specific activity based on our spirocyclic iodonium ylide (SCIDY) strategy. [18F]2 demonstrated saturable specific binding to TSPO, substantially elevated brain uptake, and slow washout of bound PET signal in the preclinical models of brain neuroinflammation (cerebral ischemia and Alzheimer's disease).