0000000000364618
AUTHOR
O. Nickel
Rezeptordarstellung mit der Single Photonen Emissions Computertomographie (SPECT): Stand der Forschung und Perspektiven
123-Jod markierte Liganden ermoglichen die Darstellung und semiquantitative Messung cerebraler Rezeptoren mit der Single Photonen Emissions Computertomographie (SPECT).
Benzodiazepinrezeptordarstellung mit JOMAZENIL-SPECT
Die Darstellung der Benzodiazepin-Rezeptordichte (BZD) mit der Single- Photonen-Emissions-Computertomographie (SPECT) wurde durch die Synthese des neuen Radioliganden JOMAZENIL ermoglicht. JOMAZENIL entspricht dem mit Jod-123 markierten Benzodiazepin-Antagonisten Flumazenil und zeichnet sich durch eine hochspezifische Bindung an zentralen BZ-Rezeptoren aus. Verdrangungsexperimente zeigten, das 90–110 Minuten p.i. ca. 80% der Aktivitat der spezifischen Bindung entsprechen [1].
IBZM-SPECT bei Neuroleptikatherapie
Mit IBZM — einem mit Jod-123 markierten Benzamid — ist es erstmalig moglich, die Dopamin-D2-Rezeptoren mit der Single-Photonen-Emissions-Computertomographie (SPECT) darzustellen. Das trotz der fehlenden ab-soluten Quantifizierung mit SPECT diese Methode hilfreich sein kann fur die Messung der D2-Rezeptoren, wurde schon von der Arbeitsgruppe von Brucke [1] dargestellt. Gegenstand unserer eigenen Studien war die Untersuchung der D2-Rezeptorbesetzung (RB) unter Haloperidol, Benperidol und Clozapin im Zusammenhang mit klinischen Daten und Prolaktinspiegeln.
Quantitative Cerebral Blood Flow Mapping in Stroke and During Mental Stimulation After Intravenous Injection of 195mAu
The new short life isotope 195mAu has some suitable features for quantitative cerebral blood flow mapping. Its half-life is 30.5 s; therefore an injection can be repeated after 3 min (six half-lives) without any need for background subtraction and with the same specific activity. The calculated whole body radiation dose after three successive administrations of 25 mCi 195mAu amounts to 50 mrad. In comparison to a 99mTc pertechnetate injection it is estimated that the dose to the patients is reduced by a factor of eight (Garcia et al. 1981).
Benzodiazepinrezeptorbindung im [123I]-IOMAZENIL-SPECT in Relation zu Cortisol-Plasmaspiegeln
Mit Iomazenil, dem mit 123Iod markierten Benzodiazepinantagonisten, und der Single Photonen Emissions Tomographie (SPECT) ist die in vivo-Darstellung von Benzodiazepinrezeptoren (BZR) moglich. Wir fanden in fruheren Untersuchungen eine signifikante Verminderung der lomazenil-Bindung bei Panikpatienten im Vergleich zu Patienten mit Depressionen (Schlegel et al. 1994). Zwischen dem GABA/BZR-System und Cortisol sind vielfaltige und komplexe Wirkzusammenhange beschrieben worden (De Souza et al. 1990). Nach Adrenalektomie wurde bei Ratten eine Zunahme der BZR-Dichte beschrieben (Miller et al. 1988, Acuna et al. 1990). Diese Effekte waren nach Corticosteroidgabe reversibel. Wahrend sich der Effek…
Prolactin plasma levels and D2-dopamine receptor occupancy measured with IBZM-SPECT
By the application of 123([123I]IBZM), an iodine-labelled dopamine D2-receptor antagonist, brain D2 receptors in humans can be visualized with single photon emission computed tomography (SPECT). The ratio of IBZM binding to striatal regions versus binding to frontal cortex (ST/FC ratio) provided a semiquantitative measurement of D2 receptor binding in the striatum. This study investigated the relationship between receptor occupancy and plasma prolactin levels in 12 male patients treated with haloperidol, benperidol or clozapine. Prolactin levels were positively correlated with D2 receptor occupancy, reflecting at least in part a comparable dopamine receptor antagonism in different dopaminer…
SPET/CT image co-registration in the abdomen with a simple and cost-effective tool
Fusion of morphology and function has been shown to improve diagnostic accuracy in many clinical circumstances. Taking this into account, a number of instruments combining computed tomography (CT) with positron emission tomography (PET) or single-photon emission tomography (SPET) are appearing on the market. The aim of this study was to evaluate a simple and cost-effective approach to generate fusion images of similar quality. For the evaluation of the proposed approach, patients with neuroendocrine abdominal tumours with liver metastases were chosen, since the exact superimposition in the abdomen is more difficult than in other regions. Five hours following the injection of 110 MBq (111)In…
Occupancy of striatal D 2 -like dopamine receptors after treatment with the sigma ligand EMD 57445, a putative atypical antipsychotic
Rationale: EMD 57445 (panamesine) is a high affinity sigma ligand with the profile of an atypical antipsychotic in animal studies. It has been reported recently to have antipsychotic activity in schizophrenia. However, its metabolite, EMD 59983, binds also to D2 and D3 dopamine (DA) receptors. Objectives: The aim of this study was to test, using single photon emission computed tomography (SPECT) and [123I]iodobenzamide (IBZM) as the radiotracer, whether EMD 59983 would pass the blood-brain barrier and to what extent it would contribute to the effects of EMD 57445 in schizophrenia. Methods: Two IBZM SPECT-scans were performed in five neuroleptic-free schizophrenic patients (DSM IV), one befo…
[123I]IBZM SPECT in patients treated with typical and atypical neuroleptics: relationship to drug plasma levels and extrapyramidal side effects
[123I]Iodobenzamide (IBZM) is an iodine-labeled dopamine receptor ligand and can be used to visualize brain D2 receptors in humans with single photon emission computerized tomography (SPECT). The ratio of striatal IBZM uptake to uptake in frontal cortex (ST/FC ratio) represents a semiquantitative measure of D2 receptor binding in the striatum. Our study sample included six patients treated with haloperidol (3.0-8.0 mg/day orally; one patient with an average of 0.9 mg/day intramuscularly), five patients with benperidol (9.0-15.0 mg/day orally) and nine patients treated with clozapine (200.0-600.0 mg/day orally). Typical neuroleptics (TNs) and atypical neuroleptics (ANs) were significantly di…
RCBF-quantification with 99mTc-HMPAO-SPECT: theory and first results.
The activity concentrations of 99mTc-HMPAO in brain after intravenous injection were evaluated in 25 patients using SPECT. With additional first pass studies of heart and brain with the short lived isotope 195mAu, the cardiac output and the mean cerebral transit times of the patients were measured a short time before the HMPAO injection. The time dependence of 99mTc-HMPAO activity in the brain was registered during the first 5 min after injection over both hemispheres. Using a simplified three compartment model it was possible to calculate the mean retention fraction of HMPAO in brain from the time activity curves. It could be shown that the regional cerebral blood flow in ml/min per 100 g …