CLINICAL AND [F-18] DOPA PET FINDINGS IN EARLY PARKINSONS-DISEASE

Twenty seven patients with recent onset (mean symptom duration 22 (SD 14) months, Hoehn and Yahr score 1.8 (SD 0.7)) Parkinson's disease wer e studied with [F-18]dopa PET. There was a correlation between putamen influx (Ki) and clinical rating, but not symptom duration. In 11 pati ents with hemi-Parkinson's disease of recent onset there were signific ant differences between normal (mean 0.0123 (SD 0.0023)), asymptomatic (mean 0.0099 (0.0020)) and symptomatic (mean 0.0070 (00.014)) putamen Kis. This suggests that Parkinson's disease has a widely variable rat e of progression, and is most compatible with a short preclinical peri od. Symptom onset was estimated at a putamen Ki of between 57% and 80% of normal. Most ipsilateral putamen Ki values in early asymmetric Par kinson's disease fell within the normal range. The implication is that either the disease is not established in the ipsilateral putamen or t hat the technique is insufficiently sensitive to detect it. Discrimina nt analysis completely separated the normal and Parkinson's disease co horts, but when a discriminant function from a previous study was used predictively four of the 27 patients with Parkinson's disease were in correctly classified as normal.