Ge excite scanner

Imaging was conducted on either a 1.5 T GE Signa scanner (119 patients) or a 3 T GE Excite scanner (43 patients) (General Electric, Waukesha, WI, USA.). High-resolution, T1-weighted anatomical reference images of the entire brain were acquired with a spoiled-gradient-echo (“SPGR”) sequence. Whole brain functional imaging used a T2*-weighted gradient-echo, echoplanar sequence with the following parameters at 1.5 T: TE = 40 ms, TR = 3000 ms, field of view = 240 mm, pixel matrix = 64 × 64, 19 sagittal slices, voxel size = 3.75 × 3.75 × 7 mm. Echoplanar imaging parameters at 3 T were as follows: TE = 25 ms, TR = 3000 ms, field of view = 224 mm, pixel matrix = 64 × 64, 34 axial slices, voxel size = 3.5 mm³.

All brain MRI scans (2,632 MRI scans) were acquired using an 8-channel phased array coil in reception and a body coil in transmission on a 3T GE Excite scanner (GE Medical Systems, Milwaukee, WI) that did not undergo hardware upgrades during the 5-year study period. A 3-dimensional (3D), T1-weighted, 1mm isotropic, volumetric, inversion recovery spoiled gradient echo (IRSPGR) sequence (1 × 1 × 1mm³, 180 slices) was acquired at each time point (echo time/repetition time/inversion time = 2/7/400 milliseconds, flip angle = 15 °, 256 × 256 × 180 matrix, 240 × 240 × 180mm³ field of view, number of excitations = 1).