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Baseline Neuroimaging Characteristics of the Parkinson's Progression Marker Initiative (PPMI) Parkinsons and Healthy Cohorts

J. Seibyl, MD on behalf of the PPMI Investigators
MDS: Dublin, Ireland
Download Presentation: Seibyl-PPMI-MDS-2012.pdf
Objective: The Parkinson's Progression marker initiative (PPMI) is a multicenter, international, longitudinal study evaluating clinical, biochemical, and imaging measures of Parkinson's disease(PD) progression. Features of PPMI include; 1) incorporation of dopamine transporter (DAT) SPECT to confirm the presence or absence of a DAT deficit for enrolled PD and healthy volunteers, respectively, 2) rigorous standardized acquisition protocols, and 3) central core lab reconstruction of raw projection data for subsequent uniform analyses. The objective of this study is to report baseline quantitative SPECT data in PD and healthy volunteers.

Methods: In this on-going study, baseline 123-I Ioflupane SPECT scans from 20 imaging centers included 146 parkinson's subjects, 109 healthy controls, and 8 subjects without evidence of dopaminergic deficit (SWEDD) initially recruited as potential parkinson's subjects. Data were centrally reconstructed, attenuation corrected, and analyze with a standardized volume of interest template for extraction of regional count densities in the left and right caudate and putamen. Striatal binding ratios (SBR) were calculated using the occipital lobe reference region. Average SBRs, lowest putamenal SBR, left-right percent asymmetry, and caudate:putamen ratios were determined and compared across the three cohorts.

Results: PD, healthy volunteers (HV), and SWEDD subjects had a mean age of 61.7±9.7 y, 58.4 ±12.5 y, and 62.2 ± 12.4 y, respectively. PD subjects had an average disease duration of 8.2 ± 7.8 months and total UPDRS score of 32.7 ± 12.6. Mean average SBR were lower in PD (1.0 ± 0.3) than healthy volunteers (1.7 ± 0.4). Both left-right asymmetry indices and caudate:putamen ratios were higher in PD vs HV. SWEDDs were indistinguishable from HV on all quantitative SBR measures.

Conclusions: Quantitative DAT SPECT imaging data acquired at baseline in PD and healthy volunteers demonstrate expected cohort differences in this multicenter trial with values consistent with previously reported single center 123-I Ioflupane SPECT studies. Longitudinal data are pending.