Improved reproducibility in dopamine D/sub 2/-receptor studies with automatic segmentation of striatum from PET images

Manual region-of-interest (ROI) definition is the conventional basis for calculating regional receptor binding potential values in neuroreceptor PET studies. In this study, we propose a fully automatic method to extract the left and right caudate and putamen from ¹¹ C-raclopride PET studies. The automatic extraction of these brain structures is challenging due to a small size of the structures compared to the imaging resolution and image noise. The automation of the ROI extraction could remedy the problems relating to intraand inter-observer variability introduced by the manual ROI drawing. We compared our method to the manual ROI drawing. The automatic ROI extraction of increased test-retest reproducibility of the calculated BP values compared to the manual ROI drawing. In addition, the method was tested on a Monte Carlo simulated PET image. In this experiment, the automatic method yielded more accurate BP values than those computed based on the anatomical ground-truth. Hence, our method for the automatic ROI extraction is reliable and it can simplify and speed up the analysis of large sets of PET scans e.g. in drug development studies