RESUMEN
UNLABELLED: PET studies were carried out on brain dopamine D1 receptors using two new ligands, [11C]SCH 39166 and [11C]NNC 756. METHODS: Four normal subjects and eight predominantly unilateral patients with early Parkinson's disease were investigated. Each of them underwent both a PET scan with [11C]SCH 39166 and one with [11C]NNC 756. A dose of about 185 MBq (5 mCi) of these ligands was administered intravenously and a dynamic PET scan with an ECAT 931/08 PET camera was carried out. Ratios between the striatal and cerebellar uptake of these compounds were calculated. RESULTS: Both [11C]SCH 39166 and [11C]NNC 756 accumulated in the striatum. There was also some neocortical binding; 75% of the striatal value in the case of [11C]SCH 39166 and 60% with [11C]NNC 756 which displayed higher (p < 0.01) uptake in the striatum than [11C]SCH 39166. There were no significant side-to-side differences in the controls nor in the parkinsonian patients. CONCLUSIONS: These results imply that both [11C]SCH 39166 and [11C]NNC 756 can be used in PET studies for the visualization and quantification of dopamine D1 receptors. Since [11C]NNC 756 has a significantly better signal-to-noise ratio in the striatum than [11C]SCH 39166, it seems to offer definite advantages for studies of D1 receptors.
Asunto(s)
Benzazepinas , Benzofuranos , Encéfalo/diagnóstico por imagen , Antagonistas de Dopamina , Enfermedad de Parkinson/diagnóstico por imagen , Receptores de Dopamina D1/análisis , Tomografía Computarizada de Emisión/métodos , Adulto , Anciano , Benzazepinas/metabolismo , Benzazepinas/farmacocinética , Benzofuranos/metabolismo , Benzofuranos/farmacocinética , Encéfalo/metabolismo , Radioisótopos de Carbono , Femenino , Humanos , Cinética , Masculino , Persona de Mediana Edad , Especificidad de Órganos , Enfermedad de Parkinson/metabolismo , Receptores de Dopamina D1/metabolismo , Valores de ReferenciaRESUMEN
UNLABELLED: The cocaine analog 2 beta-carbomethoxy-3 beta-[4-iodophenyl]tropane (beta-CIT) labeled with 11C was used to study dopamine reuptake sites with PET. METHODS: Three normal subjects and nine patients with Parkinson's disease were investigated. Each of them underwent a dynamic PET scan (25 timeframes over 80 min) with [11C]-beta-CIT. A dose of 102.5-211.3 MBq (2.77-5.71 mCi) of this ligand was administered intravenously and a PET examination with an ECAT 931/08 PET camera was carried out. Ratios between the striatal/cortical/thalamic/midbrain and cerebellar uptake of this radioligand were calculated. RESULTS: The highest accumulation of [11C]beta-CIT was observed in the caudate and putamen, though there was some uptake in the thalamus and the midbrain. Cortical uptake was negligible. Carbon-11-beta-CIT accumulated significantly less in the putamen of the Parkinson's patients than in the normal subjects. The putamen-to-cerebellum ratio in the Parkinson's patients was 1.59 +/- 0.04 and 1.80 +/- 0.13s (p = 0.028) in the normal subjects. In the caudate, there was no significant difference between the Parkinson's patients and the normal subjects. CONCLUSION: These results imply that [11C]beta-CIT is a useful compound for carrying out a PET examination of the function of the presynaptic monoaminergic neurons both in normal and pathological brains.