Brain morphometry in Parkinson’s disease

Abstract

Abstract Purpose The purpose of this brain morphometry study was to examine the volumes of different regions of the brain by research participants with Parkinson’s disease. Method To carry out the study, MR (magnetic resonance) images from 956 research participants from the Parkinson’s Progression Markers Initiative (PPMI) were used. The research participants were divided into 6 different cohorts. Before the MR images were used in this study, they had gone through preprocessing and segmentation using MAPER, where 121 regions including background were segmented. Once the data were obtained, the segmented regions were converted to volumes. The investigation was divided into two parts, first it was studied whether ICV (intracranial volume) differed between the different cohorts. This was done with the help of a violin plot and two-sided t-tests for each cohort. In the second part of the study, the individual volumes in the brain were examined. To accomplish this, hypothesis generation was used on half of each group’s subjects and then the hypotheses were tested on the other half. Two-tailed t-tests were performed to examine statistical differences and similarities between the cohorts. Result In the study, it was seen that the ICV differed between the different cohorts and thus on the imaged person’s head. None of the tested regions in the PD (Parkinsons disease) and SWEDD (scans without evidence for dopaminergic deficit) cohort showed any significant volume difference. The other three cohorts had two to five brain regions that showed a significant volume difference Conclusion In this brain morphometry study, it was shown that a correction for ICV is needed to get comparable results for the different cohorts. For the individual volumes, the results obtained in this study do not agree with previously obtained results. In further studies, it would therefore have been interesting to divide the brain into fewer regions, to add together regions that belong together.