Background: Activation of microglia cells plays an important role in neurological diseases. Positron emission tomography (PET) with [C-11]-(R)-PK11195 has already been used to visualize activated microglia cells in neurological diseases. However, [C-11]-(R)-PK11195 may not possess the required sensitivity to visualize mild neuroinflammation. In this study, we evaluated the PET tracers [C-11]-DPA-713 and [F-18]-DPA-714 as agents for imaging of activated microglia in a rat model of herpes encephalitis.
Materials and Methods: Rats were intranasally inoculated with HSV-1. On day 6 or 7 after inoculation, small animal PET studies were performed to compare [C-11]-(R)-PK11195, [C-11]-DPA-713, and [F-18]-DPA-714.
Results: Uptake of [C-11]-DPA-713 in infected brain areas was comparable to that of [C-11]-(R)-PK11195, but [C-11]-DPA-713 showed lower non-specific binding. Non-specific uptake of [F-18]-DPA-714 was lower than that of [C-11]-(R)-PK11195. In the infected brain, total [F-18]-DPA-714 uptake was lower than that of [C-11]-(R)-PK11195, with comparable specific uptake.
Conclusions: [C-11]-DPA-713 may be more suitable for visualizing mild inflammation than [C-11]-(R)-PK11195. In addition, the fact that [F-18]-DPA-714 is an agonist PET tracer opens new possibilities to evaluate different aspects of neuroinflammation. Therefore, both tracers warrant further investigation in animal models and in a clinical setting.
- Positron emission tomography
- PERIPHERAL BENZODIAZEPINE-RECEPTOR
- MICROGLIAL ACTIVATION