Initial experience with SPECT examinations using [123I]IBZM as a D2-dopamine receptor antagonist in Parkinson's disease.
[123I]IBZM is a new radioactive labelled ligand which has a high affinity and specificity to D2-dopamine receptors. The in vivo kinetics of [123I]IBZM were studied in patients with unilateral and bilateral accentuated idiopathic Parkinson's disease. The uptake in the basal ganglias and the imaging properties of this D2 receptor antagonist as a radiopharmaceutical for SPECT examinations had to be investigated. 5 patients, aged 42-66 years, (2 m/3 f) were examined. Each patient received 185 MBq [123I]IBZM intravenously. Blood samples were taken 0-120 min post injection (p.i.) and time activity curves were plotted. Three SPECT examinations were performed (I: 30-50 min; II: 50-70 min; and III: 70-90 min p.i.). The count rates (counts/pixel) in the basal ganglias and the cerebellum were measured for each SPECT series on transverse slices using the region-of-interest technique. The time-activity curve of [123I]IBZM shows a rapid decline in plasma during the first 10 min followed by a plateau until 120 min after injection. The SPECT examinations demonstrate the highest count rate in the basal ganglia during SPECT series III (i.e., 70-90 min p.i.). The side-to-side difference of the count rates were in the range of 3% in four patients, and 10% in one patient. The biokinetic data of [123I]IBZM make this substance capable as a radiopharmaceutical for SPECT examinations. The basal ganglia are best visualized 70-90 min p.i., thus [123I]IBZM seems to be a promising imaging agent for diseases of the D2-dopaminergic receptor system.
Cordes
M
M
Department of Radiology, Freien Universität Berlin, F.R.G.
Henkes
H
H
Laudahn
D
D
Bräu
H
H
Kramp
W
W
Girke
W
W
Hierholzer
J
J
Eichstädt
H
H
Felix
R
R
D000328:Adult; D000368:Aged; D001549:Benzamides / Q000493:pharmacokinetics / Q000494:pharmacology*; D001812:Blood-Brain Barrier; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D018492:Dopamine Antagonists; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism; D011759:Pyrrolidines / Q000493:pharmacokinetics / Q000494:pharmacology*; D017448:Receptors, Dopamine D2; D015899:Tomography, Emission-Computed, Single-Photon
D001549:Benzamides; D018492:Dopamine Antagonists; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide