Am J Psychiatry 1996; 153:183-190
Copyright © 1996 by American Psychiatric Association
[123I]IBZM SPECT for imaging of striatal D2 dopamine receptors in 56 schizophrenic patients taking various neuroleptics
E Klemm, F Grunwald, S Kasper, C Menzel, K Broich, P Danos, K Reichmann, C Krappel, O Rieker, B Briele, AL Hotze, HJ Moller and HJ Biersack
Department of Nuclear Medicine, University of Bonn, Germany.
OBJECTIVE: The purpose of this study was to compare the binding of various
typical and atypical neuroleptics to striatal D2 dopamine receptors in
schizophrenic patients. METHOD: Fifty-six inpatients with schizophrenia,
including 14 with schizoaffective disorder and one with schizophreniform
disorder, were evaluated. Fourteen patients were neuroleptic free. Single
photon emission computed tomography (SPECT) was performed 90 minutes after
intravenous injection of [123I]benzamide ([123I]IBZM). Subsequent
semiquantitative analysis of D2 receptor binding was done with the use of
the basal ganglia (striatum)/frontal cortex (BG/FC) ratio of activity.
Clinical symptoms were rated with the Positive and Negative Syndrome Scale
and the Hamilton Depression Rating Scale. RESULTS: The BG/FC ratios in
patients taking typical neuroleptics were significantly lower than those in
the neuroleptic- free subjects but not lower than those in the patients
taking atypical neuroleptics (clozapine, remoxipride). For atypical
antipsychotics, a dose-dependent relationship with striatal D2 receptor
binding could not be demonstrated. BG/FC ratios were not significantly
correlated with clinical symptoms or with duration of illness. CONCLUSIONS:
The results indicate that [123I]IBZM SPECT is useful for semiquantitative
imaging of striatal D2 dopamine receptors and for estimating their blockade
by neuroleptics. Thus, it may improve drug monitoring in psychiatric
patients. Furthermore, the findings suggest a complex relationship between
the antipsychotic effect of atypical neuroleptics and D2 receptor blockade.
