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Table of Contents

Table of Contents

Abstract
01. Abstract
Presentation
01. Introduction02. SPECT Image Processing03. PET Image Processing04. Patient Features at Baseline05. Voxelwise Exploratory SBR Analysis06. Regional DAT SBR Measures 07. Regional VMAT2 SBR Measures08. DAT & VMAT2 Sample Size Analysis09. Summary

SBR for DAT SPECT at 12, 24 and 48 Months

SBR for VMAT2 PET at 12, 24 and 48 Months

Axial images of SBR VMAT2 PET per voxel at 12, 24 and 48 months

Axial images of the significant change in SBR over 12-, 24- and 48-month periods in participants with Parkinson’s disease after false discovery rate correction using DAT SPECT and VMAT2 PET. The occipital cortex was used as reference region. These results highlight the decrease in SBR (blue to purple) throughout the striatum, in particular in the putamen, and the lower spatial resolution of DAT SPECT compared to VMAT2 SPECT. Significant increases in SBR (yellow to red) were also observed in the frontal lobe.

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Voxelwise SBR changes over a 48 month period highlight the dramatic changes apparent in the striatum of individuals with Parkinson’s disease. The blue and purple colors indicate significantly decreased SBR after false discovery rate (FDR) correction. Significant changes were observed as early as 12 month using DAT SPECT. While significant voxelwise changes were observed for VMAT2 PET only starting at 24 months, the longitudinal dataset for VMAT2 PET was also much smaller than for DAT SPECT, with 70 scans over 27 individuals compared to 397 scans over 129 individuals. Even with just 6 individuals having longitudinal VMAT2 PET data at 48 months (compared to 38 for DAT SPECT), significant differences were shown in the putamen and caudate, similar to DAT SPECT.

Additionally, the spatial resolution of the VMAT2 PET changes was much more defined and circumscribed to the putamen and caudate, compared to DAT SPECT where the signal appears blurred across structures, even with strict quality-controlled registration. This spatial resolution difference is highlighted in our Resource on this topic.

Significant changes were also observed outside of the striatum after 48 months, showing an inverse relationship where an increase in SBR (orange and red colors) was observed in parts of the frontal lobe. This result was not expected and may be due to the low sample size or the reference region used (occipital cortex), though similar results were observed using the corpus callosum as reference region (not shown).

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