Methods for Parkinson’s rat model PET image analysis with regions of interest

Accurate methods are required for analysis of microPET dopamine (DA) receptor or transporter images of unilaterally 6-hydroxydopamine-lesioned rat models of Parkinson´s disease. Heavily lesioned striata and the cerebellum do not appear distinctly in PET images when presynaptic tracers such as [¹¹C]-(+)-dihydrotetrabenazine (DTBZ) are used, and are difficult targets on which to place reliably regions of interest (ROIs) without additional guidance. Registration of a brain atlas to DA receptor/transporter images significantly improves reproducibility and reliability of ROI-based analyses, as measured by discrepancy between calculated binding potentials (BP) of repeated scans of the same animal, and correlation with autoradiographic binding measurements with the same tracer (DTBZ). Averaging over 3 or 5 axial planes to generate time activity curves gives equivalent reproducibility and reliability. Scan-to-scan coregistration with automated image registration (AIR) can be successful with appropriate masking. Coregistered image analysis produces statistically equivalent results to separately placing ROIs on images that are being directly compared, though coregistered images require only one set of ROIs to be placed, reducing analysis effort.