Quantitative DTI Analysis of White Matter Alterations in POE

We performed a quantitative DTI analysis of white matter microstructure alterations in POE. We selected white matter regions of interest (ROI) a priori that have been implicated in functional outcome and cognition (corpus callosum and external capsule). As we have performed previously (39 (link), 42 (link)–47 (link)), ROIs were traced by an observer masked to experimental conditions and analyzed using Bruker's Paravision 6.1 imaging software (Billerica, MA). In brief, fractional anisotropy (FA), axial diffusivity (λ₁), and radial diffusivity $\left(\frac{{\lambda }_2+{\lambda }_3}{2}\right)$  scalar maps were computed, and means were calculated individually for each ROI. For bilateral neuroanatomical ROIs, scalar means were acquired on each side and averaged per ROI. Two scans (both in the Saline group) were excluded from analysis—one due to poor field of view coverage and one due to severe motion-related artifact.