Signa vh i

Pre-defined target imaging time points included: baseline (<6 h), 12 h, 24 h, 7 days, and >30 days after stroke onset. Images were obtained using a 3 T MRI (Signa VH/i; GE Healthcare) with high performance gradients (40 mT/m; 184 µs rise time) using a standard quadrature head coil and established stroke imaging protocols (Lauzon et al., 2006 (link)). Single-shot echo-planar imaging was used for diffusion-weighted images (b = 0 s mm⁻² and isotropic b = 1000 s mm⁻²; repetition time = 9000 ms; echo time = min [80–90 ms]; 240 mm field-of-view; 5.0 mm slice thickness with a 0 or 2 mm gap). ADC maps were derived from the b = 0 s mm⁻² and b = 1000 s mm⁻² images (DeVetten et al., 2010 (link)). FLAIR images were acquired with repetition time = 9002 ms; echo time = 140 ms; inversion time = 2250 ms; 240 mm field-of-view; 3.0 mm slice thickness; and 2.0 mm gap. MR angiography (MRA) was performed using 3D time-of-flight imaging using repetition time = 22 ms; echo time = 3.3 ms; flip angle = 15°; acquisition bandwidth of ±12.5 kHz; and a 320 × 256 × 44 mm acquired volume.

MR images were collected using a 3 Tesla General Electric MR scanner (Signa VHi; General Electric Healthcare, Waukesha, WI, USA) equipped with an eight-channel, phased-array head coil. For each participant, two resting-state fMRI scans of 220 s in duration were acquired using a single-shot gradient-recalled echo, echo planar imaging sequence (110 volumes, repeat time (TR) 2000 ms, echo time (TE) 30 ms, flip angle 65°, field of view (FOV) 240 × 240 mm squared, matrix size 64 × 64, in-plane resolution 3.75 mm, 30 axial slices, 4 mm slice thickness). For the resting-state collection, participants were required to remain in the MRI scanner with their eyes open and fixated on a black crosshair at the center of a projection screen. The participants were instructed to relax, not think about anything in particular, and not to fall asleep. In addition, four emotional face task fMRI scans were collected per scanning session (for each subject), lasting 300 s each (150 volumes, TR 2000 ms, TE 30 ms, flip angle 65°, FOV 240 × 240 mm squared, matrix size 64 × 64, in-plane resolution 3.75 mm, 30 axial slices, slice thickness 4 mm). A T1-weighted structural MRI (TR 9.2 ms, TE minimum, flip angle 20°, FOV 256 × 256 mm squared, matrix size 512 × 512, in-plane resolution 0.5 mm, 176 sagittal slices, slice thickness 1 mm) was also acquired for anatomical registration of the fMRI data.

All subjects went through a whole-brain scan of resting-state fMRI (rs-fMRI). fMRI data were taken on a 3 T MRI scanner (GE Signa VH/I) using a 32-channel phased-array head coil. The rs-fMRI in whole-brain used a gradient echo-planar imaging sequence (interleaved scanning order, slice number =43, TR =2,000 ms, matrix size =64×64, FOV =220×220 mm, voxel size 3.4×3.4×3.2 mm³, number of acquisitions =240). The preprocessing and analysis of fMRI data was performed using SPM12 (http://www.fil.ion.ucl.ac.uk/spm) and the graph-theoretical network analysis was developed on the GRaph thEoreTical Network Analysis (GRETNA) (http://www.nitrc.org/projects/gretna/) toolbox (15 (link)). Briefly, after discarding the first 10 volumes of each fMRI run, slice timing was performed to correct the inconsistency of temporal collection. Then the data were motion-corrected, normalized to stereotactic Montreal Neurological Institute (MNI) space via a standard EPI template, and spatially smoothed (6×6×6 mm³ Gaussian kernel). Point-to-point head motion and mean head motion was estimated for subjects to control the motion-induced artifacts. Therefore, one patient with excessive head motion (cumulative translation or rotation >3 mm or 3°) was excluded (16 (link)).