PT  - JOURNAL ARTICLE
AU  - Christopher J. Endres
AU  - Martin G. Pomper
AU  - Michelle James
AU  - Ovsev Uzuner
AU  - Dima A. Hammoud
AU  - Crystal C. Watkins
AU  - Aaron Reynolds
AU  - John Hilton
AU  - Robert F. Dannals
AU  - Michael Kassiou
TI  - Initial Evaluation of <sup>11</sup>C-DPA-713, a Novel TSPO PET Ligand, in Humans
AID  - 10.2967/jnumed.109.062265
DP  - 2009 Aug 01
TA  - Journal of Nuclear Medicine
PG  - 1276--1282
VI  - 50
IP  - 8
4099  - http://jnm.snmjournals.org/content/50/8/1276.short
4100  - http://jnm.snmjournals.org/content/50/8/1276.full
SO  - J Nucl Med2009 Aug 01; 50
AB  - Translocator protein (TSPO) is upregulated in activated microglia and thus can serve as a marker of neuroinflammation. Recently, a novel radioligand, 11C-N,N-diethyl-2-[2-(4-methoxyphenyl)-5,7-dimethyl-pyrazolo[1,5-a]pyrimidin-3-yl]-acetamide (11C-DPA-713), has been described that binds to TSPO with high affinity. Here, we report the first examination of 11C-DPA-713 in human subjects using PET. Methods: Five healthy controls were studied with PET for 90 min after a bolus injection of high-specific-activity 11C-DPA-713. For comparison, 2 additional healthy controls were studied with 11C-R-PK11195. Arterial blood sampling and metabolite analysis were performed to allow the accurate quantification of tracer kinetics. Tracer uptake was evaluated for several brain regions. Tissue time–activity curves were fitted using 1- and 2-tissue-compartment models, with goodness-of-fit tests showing a preference for the 2-tissue model. Results: In the healthy brain, the average plasma-to-tissue clearance and the total volume of distribution were an order of magnitude larger than measured for 11C-R-PK11195. Accordingly, dose-normalized time–activity curves showed that 11C-DPA-713 gives a larger brain signal. Conclusion: Studies in patient populations will help determine whether 11C-DPA-713 provides better sensitivity for evaluating increased TSPO expression. This initial study in humans shows that 11C-DPA-713 is a promising ligand for evaluating TSPO binding with PET.