8 channel sense head coil

Anatomical T1-weighted and functional T2*-weighted MR images were collected with a 3 Tesla Philips Achieva scanner (Philips Medical Systems, Best, NL), using an 8-channel Sense head coil (sense reduction factor = 2). The MR session included a 3D T1-weighted image (TR = 25 ms, TE = 4.6 ms, flip angle = 30°, in-plane resolution = 0.89 mm × 0.89 mm, slice thickness = 1 mm, 220 contiguous axial slices) and a “resting-state” fMRI scan (200 functional volumes including 30 contiguous axial slices, parallel to the AC–PC plane; T2*-weighted echo-planar imaging (EPI) pulse sequence; TR = 3000 ms, TE = 35 ms, slice thickness = 4 mm). The latter lasted 10 min during which participants lied quietly, awake but with their eyes closed, with the head fixed by foam pads to reduce movements.

Images were acquired in a Philips Achieva 3T scanner (Amsterdam, The Netherlands) using an 8-channel SENSE head coil. The MP-RAGE and the DTI sequence were acquired during the same scanning session. No single group was scanned on a schedule or time different than the other groups, thereby avoiding bias related to temporally dependent scanner calibration. The MP-RAGE volume was collected in sagittal orientation with in-plane resolution of 256 × 256 and 1 mm slice thickness (isotropic voxels of 1 mm³; TR = 650 ms, TE = 3.2 ms, FOV 256 mm, flip angle 8°, SENSE factor = 1).
The diffusion data were acquired using a single-shot spin-echo EPI pulse sequence (TE = 90 ms, TR = 8609 ms, SENSE factor = 2.5, 5 min acquisition) with 32 diffusion weighted (b-factor = 850 s/mm², anterior–posterior fold-over direction) and three non-diffusion volumes (b-factor = 0 s/mm²; averaged in scanner to a single B0 volume). Each volume contained 66 slices (thickness = 2 mm, gap = 0 mm) acquired in the axial plane, with a reconstructed matrix size of 128 × 128 and FOV 230 mm, resulting in voxel size 1.8 × 1.8 × 2 mm. Fat suppression was achieved using a standard SPIR (spectral pre-saturation with inversion recovery) technique. The sequence was repeated twice for each subject and the datasets were averaged to increase signal to noise ratio.

A Phillips 3T Achieva scanner with an 8 channel SENSE head coil was used for imaging. A 3D T1 FFE sequence (Lin, Celik, and Paczynski, 1999 (link)) was implemented to acquire T1-weighted pre- and post-contrast images with the following parameters: TR = 20 ms, TE = 3.98 ms, Field-of-View = 256 × 256 mm², Spatial resolution = 0.80 × 0.80 × 4 mm³, slices = 30, SENSE factor = 2.5. A power injector (Medrad®, PA, USA) was used for contrast administration (Magnevist® — Gadopentate dimeglumine, Bayer Schering Pharma, Germany, 0.1 mmol/kg) and subsequent 40 ml saline flush through an 18G needle in the antecubital vein. After contrast administration, post-contrast images were acquired approximately 4 min later. To allow for accurate segmentation of the hippocampal subfields (Moreno, 2007 (link)), images were acquired perpendicular to the long axis of the hippocampus. For each subfield, the regions of interest (ROIs) were centered to avoid border regions with neighboring subfields. We compared the fractional increase in tissue signal after the contrast agent had thoroughly perfused the microvasculature and equilibrated in the blood.