Tim trio mr

Neuroimaging was performed on a 3T Siemens Tim Trio MR scanner (Siemens AG, Erlangen Germany) with a 12-channel head coil. A high-resolution, 3-dimensional, sagittal, magnetization-prepared rapid gradient echo scan (MPRAGE) T1 scan was acquired (repetition time [TR] = 2400ms, echo time (TE) = 3.16 ms, flip angle = 8°, inversion time = 1000 ms, voxel size = 1×1×1 mm3 voxels, 256×256×256 acquisition matrix, 162 slices).
Structural volumes were obtained using the FreeSurfer software suite (v5.1) (Martinos Center, Harvard University, Boston, MA, USA; http://surfer.nmr.mgh.harvard.edu). Briefly, this automated software program transforms MPRAGE images of an individual into a template space with the skull stripped and the brain segmented into white matter, gray matter, and ventricles. Cortical and subcortical image segmentation was completed using a surface deformation program [81 (link)–82 (link)]. Reviewers trained in FreeSurfer processing confirmed the quality of segmentation and volumes. Manual edits were performed only when outliers were identified. These manually-corrected scans were then reanalyzed. Regional brain volumes were normalized with respect to total intracranial volume (ICV) using a least square residual regression model across the entire cohort in order to account for possible variations in head size [36 (link), 83 (link)–86 (link)].

MRI scanning was performed at the MR Research Center of the University of Pittsburgh. A 3-Tesla Siemens Tim Trio MR scanner was used, with a Siemens 12-channel head coil. Three series of MR images were analyzed for the current study, all acquired in the axial orientation as follows: 1. T1-weighted magnetization-prepared rapid gradient echo (MPRAGE), TR (repetition time) = 2300 ms, TE (echo time) =3.43 ms, inversion time (TI) = 900 ms, FA (flip angle) = 9 deg, slice thickness = 1 mm, FOV (field of view) = 256*224 mm, voxel size = 1 mm*1mm, and slices = 176; 2. T2-weighted fluid-attenuated inversion recovery (FLAIR), TR = 9160 ms, TE = 89 ms, TI = 2500 ms, FA = 150 deg, FOV = 256*212 mm, slice thickness=3 mm, slices=48, and voxel size= 1 mm*1 mm; 3. diffusion tensor imaging (DTI), single-short spin-echo sequence, TR = 5300 ms, TE = 88 ms, TI = 2500 ms, FA = 90 deg, FOV = 256*256 mm, two diffusion values of b=0 and 1000 s/mm, 12 diffusion directions, four repeats; 40 slices; voxel size= 2 mm*2 mm; slice thickness = 3mm, and GRAPPA (radial generalized auto-calibrating partially parallel acquisitions) =2.

MRI scanning was performed at the MR Research Center of the University of Pittsburgh. A 3T Siemens Tim Trio MR scanner was used, with a Siemens 12-channel head coil. Two series of MR images were analyzed for the current study: a Magnetization-prepared rapid gradient echo (MPRAGE) T1-weighted sequence and T2-weighted Fluid-attenuated inversion recovery (FLAIR) sequence. MPRAGE images were acquired in the axial plane: TR=2300 ms; TE=3.43 ms; TI=900 ms; Flip angle= 9 deg; Slice Thickness=1mm; FOV= 256*224 mm; voxel size= 1mm*1mm; matrix size= 256*224; and number of slices=176. FLAIR images were acquired in the axial plane: TR=9160 ms; TE=89 ms; TI=2500 ms; FA=150 deg; FOV= 256*212 mm; slice thickness=3 mm; matrix size=256*240; number of slices=48 slices; and voxel size= 1mm*1mm.
The WMH volume was obtained from the MPRAGE and T2-weighted FLAIR image using an automated method for quantification and localization of WMH.^{21 (link)} The WMH quantification was done using a fuzzy connected algorithm.^{22 (link)} The total WMH volume was normalized by total brain volume.