RELATIONSHIP BETWEEN CLINICAL-FEATURES OF PARKINSONS-DISEASE AND PRESYNAPTIC DOPAMINE TRANSPORTER BINDING ASSESSED WITH [I-123] IPT AND SINGLE-PHOTON EMISSION TOMOGRAPHY

IPT [N-(3-iodopropen-2-yl)-2 beta-carbomethoxy-3 beta-(4-chlorophenyl) tropane] is a new cocain analogue which allows the presynaptic dopami ne transporters to be imaged with single-photon emission tomography (S PET) as early as 1-2 h post injection. In the present study [I-123]IPT SPET was performed in patients with Parkinson's disease (PD) to analy se the relationship between specific dopamine tansporter binding and c linical features of the disease. Twenty-six PD patients (Hoehn and Yah r stages I-IV, age range 40-79 years) and eight age-matched controls w ere studied. SPET imaging was performed 90-120 min after injection of 160-185 MBq [I-123]IPT using a triple-head camera. For semiquantitativ e evaluation of specific [I-123]IPT binding, ratios between caudate, p utamen and background regions were calculated, Specific [I-123]IPT upt ake was significantly reduced in PD patients compared to controls, Mos t patients showed a marked asymmetry with a more pronounced decrease i n [I-123]IPT binding on the side contralateral to the predominant clin ical findings. The putamen was always more affected than the caudate. [I-123]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 [I-123]IPT uptake in the caudate and putamen, and putamen to caudate ratios, decreased with increasing Hoehn and Yahr s tage. Our findings indicate that [I-123]IPT SPET may be a useful techn ique to estimate the extent of nigrostriatal degeneration in PD patien ts. Close relationships between striatal [I-123]IPT binding and clinic al features of the disease suggest that this method can be used to obj ectively follow the course and progression of PD, The reduced putamen to caudate ratios observed even in patients with mild, newly recognize d symptoms indicate that particularly this parameter may help to estab lish the correct diagnosis in the early course of PD.