To assess the contribution of white matter hyperintensity (WMH) burden on structural connectivity in patients with Parkinson's Disease (PD) using a new diffusion tensor imaging (DTI) measure, peak skeletonized mean diffusivity (PSMD).

Global efficiency and modularity are network measures of structural connectivity. In PD, the influence of WMH on structural connectivity and PD symptoms are areas of active study. The most common method of assessing WMH has been the Fazekas score, which is a visual rating scale. PSMD is an automated DTI measure that has been previously evaluated in cohorts of older adults, and genetic and sporadic small vessel disease (Baykara et al, 2016).

A PD cohort (n=24) underwent clinical evaluation and 3T MRI. The PSMD values were obtained using a publicly available script (). Brain Connectivity Toolbox was used to obtain structural network measures. Fazekas scores were assessed by two trained raters. Pearson correlations were used to assess for correlations between network efficiency and modularity and PSMD and Fazekas scores.

In this PD cohort, PSMD strongly correlated with network measures global efficiency (r = -0.466, p = 0.019) and modularity (r = 0.508, p = 0.011). There was no association between the Fazekas scores and these structural network measures. PSMD scores correlated with total Fazekas scores (r = 0.433, p = 0.034) and Fazekas periventricular subscore (r = 0.439, p = 0.032). There was a trend towards correlation between PSMD and Fazekas deep white matter hyperintensity subscore, although it did not reach significance (r = 0.306, p = 0.146).

In the PD population, PSMD may be a marker for changes in structural connectivity due to WMH. Larger studies evaluating PSMD in PD cohorts are warranted to better understand the role of WMH in PD.