Distribution physiologique cérébrale et corps entier du 18F-DPA-714 en TEP/TDM

Abstract

ObjectiveTo investigate the physiological biodistribution of N,N-diethyl-2-(2 – (4 – (2-fluoroethoxy) phenyl) -5,7-dimethylpyrazolo [1,5] pyrimidin-3-yl) acetamide labeled with fluorine 18 (18F-DPA-714) in humans, by PET/CT in the brain and the whole body. The DPA-714 is a ligand of the translocator protein (Translocator Protein kDa or TSPO), protein overexpressed by microglia in case of neuroinflammation. Materials and methodsDynamic PET/CT brain acquisitions were performed in six healthy volunteers for 90minutes after intravenous injection of 18F-DPA-714. Brain biodistribution of 18F-DPA-714 was assessed visually and using regions of interest (ROI), according to MNI AAL guidelines in order to obtain the activity/time curves for each brain region predefined. One of the subjects was also included whole body PET/CT acquisitions 1hour after injection of 18F-DPA-714, allowing visual analysis and semi-quantitative distribution of the tracer, by definition of ROI and SUVs max computation. ResultsThe maximum brain uptake of 18F-DPA-714 was visualized at 3.5minutes after injection, gray matter, mostly thalamic. This peak was followed by two elimination phases: an initial rapid phase (3.5 to 35minutes) and a slower phase until the end of recording. Uptake of 18F-DPA-714 was generally consistent across brain structures analyzed. The whole body images show significant activity in the gallbladder, spine and salivary glands under the jaw, in accordance with previous published studies using other radioligands for TSPO. ConclusionThis very preliminary study confirms that the brain biodistribution of 18F-DPA-714 makes it an interesting marker of neuroinflammation. This work allows to recommend a PET protocol acquisition. However, it now seems necessary to implement these findings in patients referred for brain conditions.