Comparison of iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane and 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane for imaging of the dopamine transporter in the living human brain
Several cocaine congeners are of potential for imaging the dopamine transporter (DAT). Previous studies have shown that iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl)tropane ([123I]β-CIT) is a promising radiotracer for imaging the serotonin (5-HT) and dopamine (DA) transporters in the living human brain with single-photon emission tomography (SPET). [123I]β-CIT was found to be not very practical for 1-day DAT imaging protocols since peak DAT uptake occurs later than 8 h. Here we report a pilot comparison of [123I]β-CIT and 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane ([123I]β-CIT FP), using SPET imaging in four healthy male subjects. Peak uptake of [123I]β-CIT-FP into the basal ganglia occurred earlier (3–4 h after injection of tracer) than that of [123I]β-CIT (>8 h). However, the specific DAT binding of [123I]β-CIT-FP in the basal ganglia was somewhat less (0.813±0.047) than that of [123I]β-CIT (0.922±0.004). Imaging quality is excellent with both tracers and they are potentially of value for brain imaging in various neuropsychiatric disorders.
Key wordsDopamine transporter Single-photon emission tomography 2β-Carbomethoxy-3β-(4-iodophenyl)tropane 2β-Carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)nortropane
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