Compartmental modeling of iodine-123-iodobenzofuran binding to dopamine D2 receptors in healthy subjects.
Iodine-123-labeled iodobenzofuran ([123I]IBF) is a potent dopamine D2 antagonist that provides good visualization of D2 receptors in primates.


METHODS
The feasibility of measuring dopamine D2 binding potential with [123I]IBF in humans was evaluated in eight healthy subjects. Following [123I]IBF injection (6 mCi), scans were acquired every 10 min for 160 min with the brain-dedicated CERASPECT camera. Arterial activities were obtained at various intervals and corrected for the presence of metabolites by extraction followed by reverse-phase high-performance liquid chromatography.


RESULTS
Reconstructed images exhibited adequate basal ganglia-to-occipital ratios (from 1.96 +/- 0.34 at 30 min to 3.54 +/- 0.71 at 150 min, mean +/- s.d.). Time-activity curves demonstrated reversibility, with peak basal ganglia uptake at 50 +/- 25 min. Regional time-activity curves were analyzed with kinetic three-compartment modeling and graphic analysis. In all subjects, D2 binding potential values, as derived by both methods, were in excellent agreement (mean +/- s.d. D2 binding potential = 129 +/- 51). An empiric count ratio method that does not require measurement of arterial tracer concentrations was evaluated and found to be in reasonable agreement with the model-derived binding potential.


CONCLUSIONS
Iodine-131-IBF is a suitable ligand for quantitative studies of D2 receptor density with SPECT in humans.
Laruelle
M
M
Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut.
van Dyck
C
C
Abi-Dargham
A
A
Zea-Ponce
Y
Y
Zoghbi
S S
SS
Charney
D S
DS
Baldwin
R M
RM
Hoffer
P B
PB
Kung
H F
HF
Innis
R B
RB
D000328:Adult; D001572:Benzofurans; D001921:Brain / Q000378:metabolism*; D003627:Data Interpretation, Statistical; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008954:Models, Biological; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon
D001572:Benzofurans; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C062439:5-iodo-N-((1-ethyl-2-pyrrolidinyl)methyl)-2,3-dihydrobenzofurancarboxamide