Human Radiation Dosimetry for the N-Methyl-D-Aspartate Receptor Radioligand 11C-CNS5161.
(11)C-CNS5161 (N-(2-chloro-5-methylthiophenyl)-N'-(3-methylthiophenyl)-N'-(11)C-methylguanidine) has been successfully used in PET imaging of N-methyl-d-aspartate (NMDA) receptors. However, no human dosimetry data have been published. We are planning to use this radiotracer for investigating NMDA receptor function in systemic lupus erythematosus, traumatic brain injury, and Parkinson disease. We have therefore undertaken (11)C-CNS5161 PET imaging to measure the whole-body distribution of this radionuclide and to estimate radiation dose to various organs.


METHODS
Dynamic PET studies of the whole body were performed on 5 healthy adults. Regions of interest were drawn over the visualized structures. Resultant time-activity curves were generated and used to determine residence times for dosimetry calculations. S factors were implemented within the OLINDA/EXM software for each structure or organ.


RESULTS
For (11)C-CNS5161, organ doses ranged from 0.0002 to 0.0393 mGy/MBq (0.0006-0.1455 rad/mCi). The critical organ for radiation burden was the lungs, with a dose of 0.0393 mGy/MBq (0.1455 rad/mCi). Radiation doses to the reproductive and blood-forming organs were 0.0023, 0.0002, and 0.0020 mGy/MBq (0.0086, 0.0006, and 0.0074 rad/mCi) for the ovaries, testes, and red marrow, respectively. The effective dose equivalent was 0.0106 mSv/MBq (0.0392 rem/mCi).


CONCLUSIONS
The radiation dosimetry for (11)C-CNS5161 for a standard single injection of 555 MBq (15 mCi) will result in an effective dose equivalent of 5.9 mSv (0.59 rem) and a lung dose of 21.8 mGy (2.18 rad) in young, healthy subjects.
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York dhawan@nshs.edu.
Vijay
V
Dhawan
Department of Radiology, North Shore-LIJ Health System, Manhasset, New York; and.
William
W
Robeson
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
David
D
Bjelke
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
Thomas
T
Chaly
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
Kristin
K
Graf
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
Matthew
M
Hellman
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
Limei
L
Zhuo
Center for Autoimmune and Musculoskeletal Disease, Feinstein Institute for Medical Research, Manhasset, New York.
Meggan
M
Mackay
Center for Neurosciences, Feinstein Institute for Medical Research, Manhasset, New York.
David
D
Eidelberg
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D002250:Carbon Radioisotopes; D005260:Female; D006146:Guanidines; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008956:Models, Chemical; D049268:Positron-Emission Tomography; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry*; D012984:Software; D013438:Sulfhydryl Compounds; D013997:Time Factors; D051598:Whole Body Imaging; D055815:Young Adult
C468267:CNS 5161; D002250:Carbon Radioisotopes; D006146:Guanidines; D019275:Radiopharmaceuticals; D016194:Receptors, N-Methyl-D-Aspartate; D013438:Sulfhydryl Compounds
11C-CNS5161; PET; dosimetry