Striatal dopamine transporter binding in early to moderately advanced Parkinson's disease: monitoring of disease progression over 2 years

Imaging of striatal dopamine transporter binding allows differentiation bet ween patients with Parkinson's disease and controls. We investigated the us e of this technique to monitor disease progression. We used N-(3-iodopropen -2-yl)-2 beta -carbomethoxy-3 beta-(4-chorophenyl) tropane (IPT) and single photon emission computed tomography (SPECT) to determine dopamine transpor ter function in eight patients with Parkinson's disease Hoehn and Yahr stag e I to III over time. Patients were recruited from the movement disorder cl inic and were studied at entry and after a follow-up period of 1 and 2 year s. Specific striatal IPT binding was measured with a manual region of inter est technique. At entry, all patients showed a reduction of striatal IPT up take of approximately 50% compared to controls, with a mean striatum to bac kground ratio of 3.61+/-0.72 (controls, 7.3 +/- 1.18). Putamen to backgroun d ratios were initially measured as 2.42 +/- 0.74 and caudate to background ratios as 5.00 +/- 0.73 (controls, 6.46 +/- 1.22 for putamen and 8.58 +/- 1.36 for caudate). Specific striatal IPT binding decreased by a mean of 6.6 % in the first year and another 5.3% in the second year. Changes of specifi c IPT binding over time were similar in caudate and putamen. In patients wi th clinically asymmetric disease, differences between the rate of decline i n the ipsilateral and contralateral sides could not be detected. The findin gs suggest that IPT SPECT can quantify the reduction of dopamine transporte r binding over time. This technique seems to be a useful tool in monitoring the intra-individual progression of dopaminergic cell loss in patients wit h Parkinson's disease and may help to follow the effects of putative neurop rotective drugs in future clinical trials. ((C) 2001 Lippincott Williams & Wilkins).