3t mr system

Imaging data were acquired using Philips 3 T MR- systems (Best, the Netherlands) located at the LUMC, AMC, and UMCG, equipped with a SENSE-8 (LUMC and UMCG) and a SENSE-6 (AMC) channel head coil respectively. Resting-state fMRI (RS-fMRI) data were acquired using a T2-weighted gradient echo echo-planar imaging with the following scan parameters in Amsterdam and Leiden: 200 whole-brain volumes; repetition time (TR) 2300 ms; echo time 30 ms; flip angle 801; 35 transverse slices; no slice gap; field of view 220 × 220 mm; in-plane voxel size 2.3 × 2.3 mm; slice thickness 3 mm; duration 7.51 min. Parameters in Groningen were identical, apart from: echo time 28 ms; 39 transverse slices; in-plane voxel size 3.45 × 3.45 mm. A sagittal 3-dimensional gradient-echo T1-weighted image was acquired for registration purposes and gray matter analysis with the following scan parameters: repetition time 9 ms; echo time 3.5 ms; flip angle 801; 170 sagittal slices; no slice gap; field of view 256 × 256 mm; 1 mm isotropic voxels; duration 4.5 min. In the darkened MRI room participants were instructed to lie still with their eyes closed and not to fall asleep. Participants confirmed wakefulness after the scanning session. No abnormalities were found upon inspection of the subjects’ structural images by a neuroradiologist.

The pulse sequences were based on slightly modified standard clinical sequences provided by Philips for the 3-T MR system and included a T1-weighted spin echo (SE) sequence, a T1-weighted turbo field-echo (TFE) sequence, a three-dimensional (3D) multiecho fast field-echo (mFFE) sequence, a multiecho gradient- and spin-echo (mGraSE) sequence, a short tau inversion-recovery (STIR) sequence, a 3D T1-weighted high-resolution isotropic volume excitation (eTHRIVE) sequence, a two-dimensional (2D) MIXED sequence, a T2-weighted turbo SE (TSE) sequence, and a fluid attenuated inversion-recovery (FLAIR) sequence. The sequence parameters are reported in Table 1.Table 1

Pulse sequence parameters employed in this study

Sequence	Repetition time (ms)	Echo time (ms)	Flip angle (degrees)
T1-weighted spin-echo	600–700	10	70
T1-weighted turbo field-echo	“shortest”	“shortest”	8
3D multiecho fast field-echo	“shortest”	4.6	20
Multiecho gradient- and spin-echo	“shortest”	“shortest”	90
Short tau inversion-recovery	5,000	30	90
T1-weighted high-resolution isotropic volume excitation	“shortest”	“shortest”	10
2D MIXED	920 (spin-echo) 2,300 (inversion-recovery)	“shortest”	90
T2-weighted turbo spin-echo	3,000	80	90
Fluid-attenuated inversion-recovery	11,000	125	90

2D Two-dimensional, 3D Three-dimensional

Imaging was performed on a 3T MR system (Philips Healthcare, Best, The Netherlands) with an eight-channel head coil. High-spatial-resolution 3D T1-weighted images were acquired with a turbo field echo sequence in the sagittal plane with the following parameters: repetition time/echo time, 8.21/3.78 msec; inversion time, 1026 msec; flip angle, 8°; effective section thickness, 1.0 mm; slab thickness, 190 mm; matrix, 240 × 240; field of view, 240 × 240 mm; number of signals acquired, 1; scan duration, 5 min 23 sec. All scans resulted in 190 contiguous slices through the brain.
The imaging parameters for the pCASL experiments were as follows: single-shot gradient-echo echo planar imaging in combination with parallel imaging (sensitivity encoding factor 2.0); repetition time/echo time, 4200/8.56 msec; matrix, 64 × 64; field of view, 240 × 240 mm; in-plane resolution, 3.75 × 3.75 mm; 20 slices acquired in ascending order; slice thickness, 6 mm; slice gap, 1 mm; labeling duration, 1650 msec; post-labeling delay, 1525 msec. Forty pairs of control/label images were acquired and then averaged. The total scan duration was 5 min 44 sec. The echo planar imaging M0 images were separately obtained with the same geometry and imaging parameters as the pCASL without labeling.