Objective: The aim of our study was to test if PD patients differ from healthy controls (HC) in GWR and if this MRI parameter has potential clinical significance.

Background: Gray to white matter intensity ratio (GWR) decreases with aging and has been found to be a good MRI biomarker in Alzheimer’s disease, but its utility in Parkinson’s disease (PD) patients hasn’t been investigated.

Methods: Using T1-weighted structural images, we obtained individual GWR values from a sample of 90 PD patients and 27 HC. The images were processed with the automated FreeSurfer stream. GWR was computed by dividing the WM by the GM values and projecting the ratios onto a common surface. The sample characteristics were: 52 PD male patients (57.8%) and 14 HC males (51.9%); a mean age of 64.4 ± 10.6 in PD and 64.7 ± 8.6 in HC; 8.0 ± 5.6 years of evolution; 15.6 ± 9.8 UPDRS; and a range of 1.5 to 3 in Hoehn and Yahr (H&Y) stage.

Results: In both PD and HC we observed significant correlations between GWR and age involving almost the entire brain. The GWR of PD patients did not differ from HC but correlated with H&Y staging, UPDRS, disease duration, and visuospatial impairment. After controlling for aging effects, H&Y, disease duration and visuospatial impairment remained significantly associated with GWR.

Conclusions: Tissue-contrast intensity is a very sensitive measure for detecting aging effects and in PD is associated with disease severity and cognitive impairment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/graywhite-matter-contrast-loss-correlates-with-clinical-severity-and-visuospatial-impairment-in-parkinsons-disease-patients/