Relationship between clinical features of Parkinson’s disease and presynaptic dopamine transporter binding assessed with [[sup 123] I]IPT and single-photon emission tomography.

IPT [N-(3-iodopropen-2-yl)-2β-carbomethoxy-3β-(4-chlorophenyl) tropane] is a new cocain analogue which allows the presynaptic dopamine transporters to be imaged with single-photon emission tomography (SPET) as early as 1-2 h post injection. In the present study [[sup 123]I]IPT SPET was performed in patients with Parkinson's disease (PD) to analyse the relationship between specific dopamine tansporter binding and clinical features of the disease. Twenty-six PD patients (Hoehn and Yahr stages I-IV, age range 40-79 years) and eight age-matched controls were studied. SPET imaging was performed 90-120 min after injection of 160-185 MBq [[sup 123]I]IPT using a triple-head camera. For semiquantitative evaluation of specific [[sup 123]I]IPT binding, ratios between caudate, putamen and background regions were calculated. Specific [[sup 123]I]IPT uptake was significantly reduced in PD patients compared to controls. Most patients showed a marked asymmetry with a more pronounced decrease in [[sup 123]I]IPT binding on the side contralateral to the predominant clinical findings. The putamen was always more affected than the caudate. [[sup 123]I]IPT binding was significantly correlated with disease duration (r=-0.7, P<0.0001) but not with the age of PD patients (r=-0.10, P=0.61). Specific [[sup 123]I]IPT uptake in the caudate and putamen, and putamen to caudate ratios, decreased with increasing Hoehn and Yahr stage. Our findings indicate that [[sup 123]I]IPT SPET may be a useful technique to estimate the extent of nigrostriatal degeneration in PD patients. Close relationships between striatal [[sup 123]I]IPT binding and clinical features of the disease suggest that this method can be used to objectively follow the course and progression of PD. The reduced putamen to caudate ratios observed even in patients with mild, newly recognized symptoms indicate that particularly this parameter may help to establish the correct diagnosis in the early course of PD. [ABSTRACT FROM AUTHOR]