title: Initial human studies with single-photon emission tomography using iodine-123 labelled 3-(5-cyclopropyl-1,2,4-oxadiazo-3-yl)- 7-iodo-5, 6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]-benzodiazepine (NNC 13-8241).
abstract: The iodine-123 labelled ligand 3-(5-cyclopropyl-1,2, 4-oxadiazo-3-yl)-7-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1, 5-a][1,4]-benzodiazepine ([123I]NNC 13-8241) was evaluated as a probe for in vivo imaging of benzodiazepine receptor sites in the human brain. Four healthy volunteers were imaged with a high-resolution single-photon emission tomography (SPET) scanner. The metabolism of [123I]NNC 13-8241 in plasma was slow. The total brain uptake was about 1.5-fold higher than that of [123I]iomazenil. The specific binding in the cortical areas was high and less intense in the thalamus. The most intense uptake was seen in the occipital cortex. The peak cortical uptake of [123I]NNC 13-8241 was observed 6-10 h after the injection of tracer. The radiation burden to the patient was moderate, being 2.5 middle dot10(-2 )mSv/MBq (effective dose equivalent). A slow metabolism together with favourable kinetics indicates that [123I]NNC 13-8241 is a specific and promising SPET ligand for imaging benzodiazepine receptor sites in the living human brain.
authors.affiliation: Department of Clinical Physiology, Kuopio University Hospital, FIN-70210 Kuopio, Finland.
authors.forename: J T
authors.initials: JT
authors.lastname: Kuikka
authors.forename: J
authors.initials: J
authors.lastname: Hiltunen
authors.forename: C
authors.initials: C
authors.lastname: Foged
authors.forename: K A
authors.initials: KA
authors.lastname: Bergström
authors.forename: C
authors.initials: C
authors.lastname: Halldin
authors.forename: K
authors.initials: K
authors.lastname: Akerman
authors.forename: J
authors.initials: J
authors.lastname: Tiihonen
authors.forename: L
authors.initials: L
authors.lastname: Farde
mesh_terms: D000328:Adult; D001569:Benzodiazepines; D001921:Brain / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D011829:Radiation Dosage; D011963:Receptors, GABA-A / Q000032:analysis*; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007457:Iodine Radioisotopes; C100658:NNC 13-8241; D011963:Receptors, GABA-A; D001569:Benzodiazepines