3.0 t mr scanner

All patients underwent MRI using a 3.0 T MR scanner (Philips Medical Systems, Achieva, Best, The Netherlands) in the prone position, using a four-channel breast array coil.
All MR images were acquired using the following sequences: an axial DWI sequence, a fat-suppressed T2-weighted sagittal sequence, and an axial T1-weighted sequence. Finally, an axial dynamic contrast-enhanced MRI (DCE-MRI) was performed with three-dimensional (3D) T1-weighted fast spoiled gradient-echo sequences before and after injection of a contrast agent (0.1 mmol/kg body weight Gd-DPTA, Bayer Healthcare, Magnevist, Germany). For DWI, images were acquired with a single shot spin-echo-planar sequence, using the following parameters: repetition time/echo time (TR/TE), 2,681/82 ms; field of view, 230×240 mm; matrix, 224×224; slice thickness, 3 mm; 40 slices with 0 mm gap; number of excitation (NEX), 3; b-values, 0 and 800 sec/mm².

Resting-state scans, as part of a fixed imaging protocol, were acquired on a Philips 3.0-T MR-scanner at all scanning sites. During the RS-fMRI scan, participants were asked to keep their eyes closed, lie as still as possible and to stay awake. Duration of the RS-fMRI scan was 7.51 min. See appendix A, section A.2 for details regarding the scan parameters.

MR imaging was performed on a Philips 3.0T MR scanner (Achieva TX, Philips Healthcare, Best, the Netherlands) with a custom‐designed 36‐channel neurovascular coil.10 Joint MR vessel wall imaging for intracranial and extracranial carotid arteries was performed for all the patients. The MR imaging parameters were as follows: 3D MERGE: fast field echo (FFE), repeat time (TR)/echo time (TE) 9.2/4.3 msec, flip angle 6°, field of view (FOV) 4 × 16 × 25 cm³, and spatial resolution 0.8 × 0.8 × 0.8 mm³; T2‐VISTA: turbo spin echo, TR/TE 2500/278 msec, flip angle 90°, FOV 4 × 16 × 25 cm³, and spatial resolution 0.8 × 0.8 × 0.8 mm³; and Simultaneous Non‐contrast Angiography and intraPlaque hemorrhage (SNAP): FFE, TR/TE 9.9/4.8 msec, flip angle 11/5°, FOV 4 × 16 × 25 cm³, and spatial resolution 0.8 × 0.8 × 0.8 mm³. Specifically, the intracranial arteries were also imaged with 3D time‐of‐flight angiography with the following parameters: FFE, TR/TE 25/3.5 msec, FOV 4.5 × 20 × 20 cm³, and spatial resolution 0.7 × 0.7 × 1.4 mm³.

MR images were acquired using a 3.0-T MR scanner (Philips Healthcare, Eindhoven, Netherlands). T1-weighted anatomical MR images were obtained with a repetition time of 9.9 ms, an echo time of 4.6 ms, a flip angle of 8°, and a voxel size of 1.0×1.0×0.5 mm³. To obtain local cortical thickness measurements for each subject, all T1 volume scans were processed using the CIVET pipeline (version 2.1.0) developed at the Montreal Neurological Institute (MNI) for fully automated structural image analysis.22 (link) Cortical thickness was calculated as the Euclidean distance between the linked vertices of the inner and outer surfaces. We extracted the regional cortical thickness value using automated anatomical labeling parcellation23 (link) and calculated a composite value for the cingulate, frontal, parietal, temporal, and occipital cortices by averaging each constituent region. We calculated intracranial volume by measuring the total volume of the voxels within the brain mask using the FSL bet algorithm (FMRI software library package, http://www.fmrib.ox.ac.uk/fsl).24 (link) To measure hippocampal volume, we used an automated hippocampus segmentation method using a graph cut algorithm combined with atlas-based segmentation and morphological opening.

The structural MR images analysed in the present study were from scans carried out as part of a routine clinical investigation of the patients' strokes. All included patients underwent conventional MRI of the brain without contrast administration on a 1.5 T MR scanner (Philips Medical Systems, Best, The Netherlands) with the sequences sagittal T2‐weighted images (SE, TR/TE 4240/100 ms), axial fluid‐attenuated inversion recovery (FLAIR) (IR, TR/TE 11 000/140 ms), axial T2‐weighted fast field echo (FFE) (TR/TE 699/23 ms, flip angle 18°), DW imaging (b = 0 ms, b = 1000 ms, TR/TE 2751/83 ms, flip angle 90°, acquisition matrix 128, slice thickness 5 mm, slice distance 6 mm) or on a 3.0 T MR scanner (Philips Medical Systems) with the sequences sagittal T2‐weighted images (SE, TR/TE 3000/80 ms), axial FLAIR (TR/TE 12 000/140 ms), axial T2‐weighted FFE (TR/TE 504/16 ms), DW imaging (b = 0 ms, b = 1000 ms, TR/TE 2255/55 ms, flip angle 90°, acquisition matrix 140, slice thickness 5 mm, slice distance 6 mm).