Comparative Analysis of Folate Derived PET Imaging Agents with [18F]-2-Fluoro-2-deoxy-d-glucose Using a Rodent Inflammatory Paw Model

Activated macrophages play a significant role in initiation and progression of inflammatory diseases and may serve as the basis for the development of targeted diagnostic methods for imaging sites of inflammation. Folate receptor beta (FR-β) is differentially expressed on activated macrophages associated with inflammatory disease states yet is absent in either quiescent or resting macrophages. Because folate binds with high affinity to FR-β, development of folate directed imaging agents has proceeded rapidly in the past decade. However, reports of PET based imaging agents for use in inflammatory conditions remain limited. To investigate whether FR-β expressing macrophages could be exploited for PET based inflammatory imaging, two separate folate-targeted PET imaging agents were developed, 4-[18F]-fluorophenylfolate and [68Ga]-DOTA-folate, and their ability to target activated macrophages were examined in a rodent inflammatory paw model. We further compared inflamed tissue uptake with 2-[18F]fluoro-2-deoxy...