Abstract
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Objectives Vesicular monoamine transporter 2 (VMAT2) is highly expressed in the endocrine cells and brain. 18F-labeled derivatives of dihydrotetrabenazine (DTBZ) will improve the VMAT2 image in clinical setting instead of 11C-labeled derivatives. We investigated the biodistribution and radiation dosimetry of (+)-2-Hydroxy-3-isobutyl-9-(3-18F-fluoropropoxy)-10-methoxy-1,2,3,4,6,7-hexahydro-11bH-benzo[a]quinolizine (18F-FP(+)-DTBZ or 18F-AV-133), a potential VMAT2 imaging agent showing encouraging results in human, to facilitate its future utilization.
Methods Five healthy human subjects (age 56±6 yr) were enrolled for the whole body PET scan. Serial images were acquired for 3 hours immediately after a bolus injection of 371±12 MBq 18F-FP-(+)-DTBZ. The source organs were delineated on PET/CT using PMOD image analysis workstation. The OLINDA/EXM application was used to determine the effective doses (EDs) for individual organs.
Results The radiopharmaceuticals did not show any noticeable adverse effects for the 5 subjects. The radiotracer uptake in the brain was high (5.2±0.3% injected dose) at 10 minutes after injection. The high-absorbed doses were found in the pancreas, liver, and upper large intestine wall. The critical organ, which received 166.6±20.2 μGy/MBq, was the pancreas. High variability in the lungs (ranging 34.8~13.6 μGy/MBq) was observed. The effective dose equivalent and effective dose for 18F-FP-(+)-DTBZ were 32.66±2.97 μSv/MBq and 24.58±2.73 μSv/MBq, respectively. These values are comparable to those reported for any other 18F-labeled radiopharmaceuticals.
Conclusions 18F-FP-(+)-DTBZ is safe with appropriate biodistribution and radiation dosimetry for imaging VMAT2 sites in human.
Research Support NMRPD180561