For both groups, the dynamic whole-body distribution of the respective tracer labelled with [11C] will be measured after IV administration of 370 MBq. Two venous catheters, one on each arm, will be used for : 1/ the injection of [11C]CHDI-00485180-R or [11C]CHDI-00485626 tracer solution and 2/ for venous blood sampling (blood biochemistry and metabolites).~All images will be acquired using the SIEMENS Truepoint Biograph 40 PET-CT scanner. First, a CT scout will be acquired to set the axial field of view (FOV). The axial FOV should extend from the top of the head to the middle of the thighs (approximately 6-7 bed positions). Then, a low dose CT will be acquired for enabling PET attenuation correction and anatomical information (organ delineation). Following the CT, 10 sets of WB 3D PET images in total will be acquired sequentially. The first set of 9 whole body PET scans (scan segment 1) will be acquired, starting at the time of injecting [11C]CHDI-00485180-R solution or [11C]CHDI-00485626 solution. After this sequence of PET acquisitions, which will take up to 100 min, the subject will be moved out of the scanner and will be encouraged to void the bladder. After a 30 minute break, the subject will be repositioned in the PET/CT scanner and a second low dose CT will be acquired. WB scan 10 (scan segment 2) will be started at 2 hours after [11C]CHDI-00485180-R or [11C]CHDI-00485626 injection, scanning for a total scan duration of about 28 minutes.~During the first WB PET/CT scan segment, 6 venous blood samples (4 mL each) per subject will be taken at 5, 10, 20, 40, 60 and 100 min after [11C]CHDI-00485180-R or [11C]CHDI-00485626 injection. This will allow testing and further optimization of the HPLC metabolite analysis for future brain imaging studies with full kinetic modelling and quantification.
A better understanding of the HD pathogenesis mechanisms may lead to a better understanding of disease pathology, progression and development of targeted therapies.~[11C]CHDI-00485180-R and [11C]CHDI-00485626 are two novel mutant huntingtin aggregate binding PET radioligands which have already demonstrated sensitivity to mutant huntingtin load in animal models. In the current study, the biodistribution and dosimetry of both these ligands will be investigated in young healthy volunteers according to a standard approach, in 3 subjects (including both genders) per tracer.