REGIONAL CEREBRAL BLOOD-FLOW IMAGING WITH TC-99M-BICISATE SPECT IN ASYMMETRIC PARKINSONS-DISEASE - STUDIES WITH AND WITHOUT CHRONIC DRUG-THERAPY

Regional cerebral perfusion was assessed in six patients with asymmetr ic Parkinson's disease (PD) of mild to moderate severity and in six ma tched normal subjects using Tc-99m-bicisate single photon emission com puted tomography (SPECT). Regional activity was normalized to whole-br ain activity. Each subject was studied twice, separated by 15.2 +/- 9. 2 and 18.0 +/- 4.8 days in normals and PD patients, respectively. Ther e was low intrasubject scan-rescan variability in normals, with all re gions showing an average intrasubject difference in repeat studies of < 3%. In PD patients after chronic oral antiparkinsonian drugs had bee n withdrawn, as compared with normal subjects, there was increased per fusion in the caudate and lenticular nuclei contralateral to the worst affected extremities. This increased basal ganglia perfusion was atte nuated by chronic oral therapy. The clinical relevance of these change s is indicated by the high positive correlation between various measur es of clinical PD severity and the lenticular perfusion. These differe nces in basal ganglia perfusion measured with Tc-99m-bicisate SPECT in mild to moderate, asymmetric PD may be secondary to increased metabol ic demand resulting from alterations of synaptic activity.