Haloperidol blocks the uptake of [18F]N-methylspiroperidol by extrastriatal dopamine receptors in schizophrenic patients

We had previously demonstrated extrastriatal uptake of [¹⁸F]N-methyl-spiroperidol (¹⁸F-NMS) in the human brain. This study evaluates the effect of haloperidol on ¹⁸F-NMS binding in extrastriatal brain regions. Six schizophrenic patients on haloperidol underwent two PET scans with ¹⁸F-NMS at 12 h and at 6 days after haloperidol withdrawal. There was a significant increase in ¹⁸F-NMS uptake in striatal, thalamic, and temporal regions but not in frontal, occipital, or cerebellar regions, following drug withdrawal. Haloperidol's ability to block the uptake of ¹⁸F-NMS is an indication of the specificity of the radioligand's binding in these regions and supports the postmortem data demonstrating the presence of dopamine D₂ receptors in the thalamus and temporal cortex of the human brain. © 1995 Wiley-Liss, Inc.