Biodistribution and radiation dosimetry of the serotonin transporter ligand 11C-DASB determined from human whole-body PET.
11C-Labeled 3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile (DASB) is a selective radioligand for the in vivo quantitation of serotonin transporters (SERTs) using PET. The goal of this study was to provide dosimetry estimates for 11C-DASB based on human whole-body PET.


METHODS
Dynamic whole-body PET scans were acquired for 7 subjects after the injection of 669 +/- 97 MBq (18.1 +/- 2.6 mCi) of 11C-DASB. The acquisition for each subject was obtained at 14 time points for a total of 115 min after injection of the radioligand. Regions of interest were placed over compressed planar images of source organs that could be visually identified to generate time-activity curves. Radiation burden to the body was calculated from residence times of these source organs using the MIRDOSE3.1 program.


RESULTS
The organs with high radiation burden included the lungs, urinary bladder wall, kidneys, gallbladder wall, heart wall, spleen, and liver. The activity peaked within 10 min after the injection of 11C-DASB for all these organs except two--the excretory organs gallbladder and urinary bladder wall, which had peak activities at 32 and 22 min, respectively. Monoexponential fitting of activity overlying the urinary bladder suggested that approximately 12% of activity was excreted via the urine. Simulations in which the urinary voiding interval was decreased from 4.8 to 0.6 h produced only modest effects on the dose to the urinary bladder wall. With a 2.4-h voiding interval, the calculated effective dose was 6.98 microGy/MBq (25.8 mrem/mCi).


CONCLUSIONS
The estimated radiation burden of 11C-DASB is relatively modest and would allow multiple PET examinations of the same research subject per year.
Lu
Jian-Qiang
JQ
Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-0135, USA. lujq@intra.nih.gov
Ichise
Masanori
M
Liow
Jeih-San
JS
Ghose
Subroto
S
Vines
Doug
D
Innis
Robert B
RB
D000814:Aniline Compounds / Q000493:pharmacokinetics*; D001822:Body Burden; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002352:Carrier Proteins / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins; D008657:Metabolic Clearance Rate; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009928:Organ Specificity; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018570:Risk Assessment / Q000379:methods*; D050486:Serotonin Plasma Membrane Transport Proteins; D013440:Sulfides / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed / Q000379:methods*; D014915:Whole-Body Counting / Q000379:methods*
C412822:3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile; D000814:Aniline Compounds; D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D019275:Radiopharmaceuticals; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D013440:Sulfides