Gyroscan intera

All data were acquired using a 1.5T MR Philips Intera Gyroscan (Philips Healthcare, Best, The Netherlands) with an 8-channel head (SENSE) third-party coil. For each subject a fast field echo-planar imaging (FFE-EPI) protocol was acquired for rs-fMRI with TR/TE = 3000/60 ms, voxel size = 2.2 × 2.2 × 4 mm³, FOV = 250 × 250 mm², 26 slices, SENSE factor = 3.1, 100 repeated volumes. For anatomical reference a volumetric 3DT1-weighted acquisition was also collected using a fast field echo (FFE) sequence (TR/TE = 8.6/4 ms; flip angle 8°; 170 sagittal slices; slice thickness = 1.2 mm; FOV = 240 mm; acquisition matrix = 192 × 192, reconstructed to 256 × 256; in-plane resolution 1.25 × 1.25 mm², reconstructed to 0.94 × 0.94 mm²).
All the MRI analysis was performed on a workstation with Linux Ubuntu 12.04, running SPM8 (Wellcome Department of Cognitive Neurology, http://www.fil.ion.ucl.ac.uk/), Matlab R2009a (The MathWorks, Natick, Mass, USA http://www.mathworks.com/) and FSL (FMRIB Software Library, version 4.1.9, http://www.fmrib.ox.ac.uk/fsl/).

Following acute stroke triage, all patients underwent cerebral MRI on follow-up within 12 days including diffusion-weighted imaging (DWI) and FLAIR (1.5 Tesla Intera Gyroscan, Philips, Best, The Netherlands; DWI with TR 4.25ms, TE 95ms, matrix 256x256, FOV 230x230 mm, transversal 5mm thick slices, b-values 0 and 1.0 mm^2/s; FLAIR with TR 8.00ms, TE 120ms, transversal 5mm thick slices).
Final infarct lesions were manually segmented slice by slice on the individual MRI scans (Analyze 10.0, AnalyzeDirect Inc., Overland Park, USA). Original images and corresponding binary lesion masks were affine registered to standard MNI-152 brain (FLIRT, FSL 5.0,FMRIB Software Library, Oxford, UK) optimized by non-linear refinement (FNIRT, FSL 5.0) using high precision modality specific population based reference images [10 (link)]. Lesion volumes were normalized to head size. Atlas based analysis of brain infarct was performed. The percentage of a brain region that was infarcted was calculated for each patient using the Harvard-Oxford cortical and subcortical structural atlases and the JHU white-matter tractography atlas (137 regions in total) implemented in the FMRIB Software Library [11 (link)]. Regions with less than 1% of infarcted voxels were excluded from analysis.

MRI examinations were performed using a 1.5 T whole body imaging system (Gyroscan Intera, Philips Medical System, The Netherlands) and a breast coil. Patients were imaged in the prone position with T2-weighted and diffusion-weighted imaging (DWI) (b0, b600) sequences, and a 3D gradient echo axial T1-weighted sequence with fat suppression (SPAIR). Scan parameters were TR/TE = 4.8/2.4 ms, flip angle = 10°, FOV = 355 × 355 mm, matrix 320 × 320, slice thickness 2.5 mm, voxel size 0.65 × 0.65 × 1.25 mm after reconstruction. The anatomic study was followed by a dynamic study. Patients received 0.1 mmol/kg of gadobenate dimeglumine (Multihance, Bracco Imaging, Germany) followed by 30 mL saline flush injected at a rate of 2 mL/s with an automated injector. One pre- and five post-injection images were acquired with a temporal resolution of approximately 60 s. The total acquisition time for the protocol was about 6 min. Analyses were performed on subtracted images, i.e. the residual difference image obtained after the second post-contrast image has been subtracted from the pre-contrast image.

Acquisition of DTI data was performed using a 6-channel head coil on a 1.5 T Philips Gyro scan Intera (Philips, Best, Netherlands) and single-shot echo-planar imaging. For each of the 32 non-collinear diffusion sensitizing gradients, 67 contiguous slices were acquired parallel to the anterior commissure-posterior commissure line. Imaging parameters were as follows: acquisition matrix = 96 × 96; reconstructed matrix = 192 × 192; field of view = 240 m × 240 m; TR = 10,726 ms; TE = 76 ms; parallel imaging reduction factor (SENSE factor) = 2; EPI factor = 49; b = 1000 s/mm²; NEX = 1; and a slice thickness of 2.5 mm with no gap (acquired voxel size 1.3 m × 1.3 m × 2.5 m).

In order to diagnose structural changes consistent with Chiari-like malformation and SM, a standard MRI examination of the brain and spinal cord was performed prior to the perfusion studies. Imaging was performed using a 1 T MRI scanner (Gyroscan Intera, Phillips, Hamburg, Germany) and a two-part surface coil consisting of two elliptical elements, which were placed on the right and left sides of the head. Dogs were examined in sternal recumbency with their neck in extension sagittal, dorsal, and transverse images were obtained using T2-Turbospin echo sequences (TE: 120 ms, TR: 2,900 ms). Transverse FLAIR images and dorsal T1-weighted gradient echo images were acquired before and after contrast (i.e., after perfusion study) medium administration to exclude structural brain abnormalities. Field of view was 180 mm × 180 mm, matrix was 288 × 288. Slice thickness varied from 2 to 3 mm. The cervical spine was examined until the first the first thoracic vertebra. Sagittal T2-weighted images were obtained. If the presence of SM was confirmed, transverse gradient-echo images were obtained over the whole extension of the SM.