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).
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.
Kuikka
J T
JT
Department of Clinical Physiology, Kuopio University Hospital, FIN-70210 Kuopio, Finland.
Hiltunen
J
J
Foged
C
C
Bergström
K A
KA
Halldin
C
C
Akerman
K
K
Tiihonen
J
J
Farde
L
L
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
D007457:Iodine Radioisotopes; C100658:NNC 13-8241; D011963:Receptors, GABA-A; D001569:Benzodiazepines