3t prismafit

Participants were scanned with a Siemens 3T PRISMA Fit scanner, using a 64-channel head-coil, at the University of Kentucky Magnetic Resonance Imaging and Spectroscopy Center (MRISC). The following sequences were collected for this study: a 3D multi-echo, T1-weighted anatomical image (MEMPR) and a 3D, multi-echo, gradient-recalled echo (GRE) sequence used for Quantitative Susceptibility Mapping (QSM). Several other sequences were collected during the scanning session related to other scientific questions and are not discussed further here. The MEMPR sequence had four echoes [repetition time (TR) = 2530ms; first echo time (TE1) = 1.69ms echo time spacing (ΔTE) = 1.86ms, flip angle (FA) = 7°] and covered the entire brain [176 slices, field of view = 256mm, parallel imaging (GRAPPA), acceleration factor = 2, 1mm isotropic voxels, scan duration =5.53 min]. The MEMPR sequence was used to optimize the Freesurfer cortical segmentation and improve the accuracy of the gray matter lobar masks (Van der Kouwe et al., 2008). The sequence used for QSM was a flow compensated, multi-echo, 3D spoiled GRE sequence in the sagittal plane with eight echoes (TR/TE1/ΔTE/FA= 24ms/2.98ms/2.53ms/15°). The entire brain was covered [acquisition matrix = 224×224×144, parallel imaging (GRAPPA), acceleration= 2, 1.2 mm isotropic voxels and scan duration = 6.18 min].

All participants were scanned on a Siemens 3T Prisma Fit at Washington University Medical School’s Neuroimaging Laboratories. A new navigator-guided T1 MPRAGE scan, developed to compensate for movement (Tisdall et al., 2012 (link)), was obtained using an axial acquisition in a 32-channel head coil array with a TR of 2500ms, TE of 2.88ms, TI of 1060ms, 176 slices, no gap, and field of view of 256mm. VBM preprocessing was carried out using Statistical Parametric Mapping 12’s Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (Ashburner, 2007 ; Friston et al., 2007 ) package to warp segmented whole brain gray and white matter volumes into 1mm³ Montreal Neurological Institute space. Spatial smoothing was carried out using an 8mm full width at half maximum. Images were inspected for failed warping, ultimately no one was excluded. Brain masks were created by averaging all subject’s tissue maps and filtering out voxels with values under 0.3; the gray matter mask was then manually edited to exclude some para-orbitofrontal non-gray matter.