DaTSCAN Brain Scintigraphy and Psychotropic Treatments: Influence on Radiotracer Binding

DaTSCAN™ (123I-ioflupnae) tomoscintigraphy assesses the density of dopamine transporters (DATs) on the presynaptic membrane of dopaminergic neurons. This examination is used in clinical routine in patients presenting a parkinsonian syndrome in search of a pre-synaptic dopaminergic denervation pointing to a neurodegenerative origin of this syndrome Some drugs, and in particular psychotropic treatments, have an ability to bind to dopamine transporters or to mobilize endogenous dopamine and may thus interfere with ioflupane binding. Visual interpretation of the DaTSCAN™ scan as well as semi-quantitative analysis (radiotracer binding ratios) takes into account striatal binding activity and also activity in the rest of the brain parenchyma (background) . Therefore, drugs that interfere with striatal or extra-striatal binding of ioflupane may have an impact on the examination result.

To date, there is little literature data evaluating the influence of psychotropic treatments frequently used in clinical routine on DaTSCAN™ CT images. Some studies have shown that SSRI (selective serotonin reuptake inhibitor) and SNRI (serotonin and norepinephrine reuptake inhibitor) antidepressants can significantly alter striatal ioflupane uptake ratios (10-20%) with no obvious influence on the visual interpretation of the examination . Antipsychotic and antiparkinsonian drugs appear to have no effect on ioflupane uptake and should not be discontinued before the examination is performed. Finally, lithium treatment could significantly reduce ioflupane binding.

The majority of studies analyzing the effects of medication on ioflupane binding have been conducted in small numbers or assess the potential impact of therapy on a theoretical basis.

The objective of this study was to evaluate the influence of the most commonly used psychotropic therapies, sometimes in combination, on DaTSCAN™ CT images with a large population of patients included in clinical routine.