Signa hdx platform

All subjects were scanned on a 3-Tesla GE system MRI scanner (Signa HDx platform, GE Healthcare, Milwaukee, WI, USA), using an eight-channel phased array head coil at Toronto Western Hospital.
Each subject had a whole-brain high-resolutionT1-weighted 3D spoiled gradient echo (FAST-SPGR) sequence acquired first with the following parameters: TI = 450 ms, TR = 7.88 ms, TE = 3 ms, flip angle = 12°, voxel size = 0.859 × 0.859 × 1 mm, matrix size = 256 × 256, 146 slices, field of view = 24 × 24 cm, no interslice gap.
After the anatomical scan, a BOLD fMRI T2*-weighted echoplanar imaging gradient echo (EPI-GRE) sequence was acquired with the following parameters: TR = 2400 ms, TE = 30 ms, flip angle = 70°, 41 slices, voxel size = 3.5 mm³, matrix size = 64 × 64, number of frames = 335, field of view = 24 × 24 cm.

The scans were acquired on a 3-Tesla scanner (HDx Signa platform, GE healthcare, Milwaukee, WI, USA) with an 8-channel head coil. The same fast spoiled gradient echo (FSPGR) T1-weigthed scan and two BOLD sequences with identical scanning parameters that were each 13 minutes and 20 seconds long, were acquired for all participants. The FSPGR scan was a high-resolution T1-weighted scan with a 3D spoiled gradient echo sequence. The following parameters were used: TI = 450 ms, TR 7.88 ms, TE = 3 ms, flip angle = 12°, voxel size = 0.859 × 0.859 × 1 mm, matrix size = 256 × 256, 146 slices, field of view =24 × 24 cm, no interslice gap. Next, the two BOLD sequences consisted of a T2*-weighted echoplanar imaging gradient during the PetCO₂ and PetO₂ manipulation. The following sequence parameters were used: TR = 2400 ms, TE = 30 ms, flip angle = 85°, 41 slices, voxel size = 3.5 mm³ and matrix size = 64 × 64.

The images acquired from both the HC and SCD patient groups were identical. The CVR scan was acquired on a 3‐Tesla GE scanner (HDx Signa platform, GE healthcare) with an 8‐channel head coil at Toronto Western Hospital. All participants completed an anatomical scan followed by a BOLD sequence scan. In addition, the SCD patient group was subject to further clinical scans as requested by their physicians including axial T2 flair, 3D ASL, DWI and EPI GRE. First, a whole‐brain coverage high‐resolution T1‐weighted 3D spoiled gradient echo sequence (anatomical images) was acquired with the following parameters: TI = 450 ms, TR = 7.88 ms, TE = 3 ms, flip angle = 12°, voxel size = 0.859 × 0.859 × 1 mm, matrix size = 256 × 256, 146 slices, field of view = 24 × 24 cm and no interslice gap. Second, a BOLD fMRI T2*‐weighted echoplanar imaging gradient echo sequence was attained with the following parameters: TR = 2400 ms, TE = 30 ms, flip angle = 85^°, 41 slices, voxel size = 3.5x3.5 mm, matrix size = 64 × 64, number of frames = 335, field of view = 24 × 24 cm.

A 3-Tesla scanner (HDx Signa platform, GE healthcare, Milwaukee, WI, USA) with an 8-channel head coil was used in these experiments. The protocol consisted of a high-resolution T1-weighted scan followed by one BOLD sequence scan. The high-resolution T1-weighted scan was acquired using a 3D spoiled gradient echo sequence with the following parameters: TI = 450 ms, TR 7.88 ms, TE = 3 ms, flip angle = 12°, voxel size = 0.859 × 0.859 × 1 mm, matrix size = 256 × 256, 146 slices, field of view = 24 × 24 cm, no interslice gap. The BOLD scan was acquired during normocapnic PetO₂ manipulation using a T2*-weighted gradient echoplanar imaging sequence with the following parameters: TR = 1,500 ms, TE = 30 ms, flip angle = 73°, 29 slices voxel size = 3 mm isotropic voxels and matrix size = 64 × 64.