Statistical parametric mapping of (99m)Tc-ECD SPECT in idiopathic Parkinson's disease and multiple system atrophy with predominant parkinsonian features : correlation with clinical parameters

Statistical parametric mapping was performed to investigate differences in regional cerebral blood flow (rCBF) between patients with idiopathic Parkinson's disease (IPD), patients with multiple system atrophy (MSA), and healthy volunteers. In addition, a voxel-based covariance analysis was performed with disease-specific parameters and clinical patient data such as disease duration, medication, and clinical subscores. Methods: For this purpose, Tc-99m-ethylcysteine dimer (ECD) SPECT was performed on 81 IPD patients (50 men, 31 women; age, 62.6 +/- 10.2 y), 15 MSA patients (9 men, 6 women; age, 61.5 +/- 9.9.2 y), and 44 age- and sex-matched healthy volunteers (27 men, 17 women; age, 59.2 +/- 11.9 y). Results: Significant hypoperfusion was observed in IPD compared with healthy subjects in a symmetric subcortical-cortical network including the basal ganglia, thalami, prefrontal and lateral frontal cortex, and parietooccipital cortex (voxel P value P-height < 0.001, corrected for multiple comparisons). For MSA, only symmetric hypoperfusion was seen in the putamen and thalamus with respect to healthy subjects and to IPD (P-height < 0.01, corrected). Prolonged disease duration or higher Hoehn and Yahr stage results in hypoperfusion of the posterior associative cortex. There is a negative correlation between perfusion of the caudate heads and limbic system and the standardized dosage of dopamine agonists in the patients with PD, whereas for MSA a bilateral decrease in putamen activity was noted (P-height < 0.001, uncorrected). Cognitive performance was positively correlated with limbic perfusion and inversely correlated with posterior associative cortical areas, but not with prefrontal regions. Conclusion: Voxel-based analysis of Tc-99m-ECD perfusion SPECT shows detailed differences between IPD and MSA, which may be of use in the differentiation of both disease entities, and is able to elucidate cerebral perfusion correlates of disease severity, dopamine agonist medication, and cognitive performance