Fig. 2.

ROIs used in the comparison of NAWM and hyperintensities considering the confounding spatial factor. (A) FLAIR images from a subject with diffuse periventricular and deep WMHs. (B) WMHs are highlighted in yellow and overlaid on a FLAIR image. (C) WMHs without the underlying FLAIR map. (D) Image C is left-right flipped about the y-axis in MNI coordinates while retaining native structure. (E) Image D is subtracted from Image C, giving rise to NAWM that is contralateral to hyperintensities. (F) Image E is left-right flipped about the y-axis to give rise to the original WMH mask; however, only voxels with contralateral NAWM remain. (G) The final NAWM mask (image E) and WMH mask (image F) used in the characterization of CVR metrics are overlaid on FLAIR images. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)