Signa horizon lx echospeed system

All brain imaging was performed at the University of California, Davis Imaging Research Center on a 1.5-T GE Signa Horizon LX Echospeed system. Three sequences were used: a 3-dimensional T1-weighted coronal spoiled gradient- recalled echo acquisition, a FLAIR sequence, and DTI using the diffusion tensor weighted echo-planar sequence (DTI-EPI; Stanford University, CA). All image acquisition was performed according to previously reported methods^{11 (link), 12 (link)}.
Fractional anisotropy (FA) maps were calculated from baseline and follow-up DTI exams and warped to a DTI template. Segmentation of WMH was performed on baseline and follow-up FLAIR images in their native space by a semi-automated procedure previously described^{12 (link), 13 (link)}. FLAIR images were then linearly aligned to the corresponding T1-weighted scan using a previously-described image registration method^{11 (link)}. The T1-weighted scan was then warped to a T1-weighted template defined in the same space as the DTI template^{14 (link)}, thus allowing FLAIR and T1 images as well as WMH maps to be placed in the same coordinate frame (please see http://stroke.ahajournals.org for Supplemental Methods).

Brain imaging was obtained at the University of California at Davis MRI research center on a 1.5T GE Signa Horizon LX Echospeed system or the Veterans Administration at Martinez on a 1.5 T Marconi system using compatible imaging parameters described fully in the Supplementary Material. Image quantification, was performed by raters who were blind to age, gender, race, educational achievement, ethnicity, and diagnostic status.