3.0 t mr system

We conduct this study with a GE 3.0T MR System. The parameters of scans are listed as followed: sequence = GRE-EPI, axial slices, scanning order = interleaved [1:2:43 2:2:42], slice number = 43, matrix size = 64 ^* 64, FOV = 192 ^* 192 mm, TR/TE = 2,000/30 ms, FA = 90 deg, slice thickness = 3.0 mm, gap = 0 (voxel size 3.0 ^* 3.0 ^* 3.0), dummy scan = 6, number of acquisitions = 240, NEX = 1, parallel acceleration = 2, total scan time = 8 min 12 s.

Images were acquired on a GE 3.0 T MR system and a conventional eight-channel quadrature head coil was used. All subjects were instructed to lie in a supine position, and formed padding was used to limit head movement. The structural images were generated by a three-dimensional T1-weighted fast spoiled gradient recalled echo (3D T1-FSPGR) sequence, and the scanning parameters were set as follows: TR (repetition time) = 6.3 ms, TE (echo time) = 2.8 ms, flip angle = 15o, FOV (field of view) = 25.6 cm × 25.6 cm, Matrix = 256 × 256, NEX (number of acquisition) = 1. All imaging protocols were identical for all subjects.

All MR data acquisitions were performed on a 3.0 T MR system (Sigma; GE Healthcare, Milwaukee, WI, United States) equipped with an eight-channel phased-array head coil. Anatomy images were acquired by a fast spin echo sequence with the following scanning parameters: (1) T2-weighted imaging (T2_W imaging): TR = 4480 ms, TE = 120 ms, FOV = 240 mm² × 240 mm², resolution = 256 × 384, and slice thickness = 5 mm; (2) T2_W imaging-fluid attenuated inversion recovery (T2Flair): TR = 8600 ms, TE = 155 ms, TI = 2100 ms, FOV = 240 mm² × 240 mm², resolution = 256 × 384, and slice thickness = 5 mm; and (3) diffusion-weighted images (DWI): TR = 6000 ms, TE = min, b values = 1,000, FOV = 240 mm² × 240 mm², resolution = 256 × 384, and slice thickness = 5 mm. In addition, a magnetization transfer (MT)-prepared gradient echo MRI sequence was used for CEST imaging with the following parameters: TR = 50 ms, TE = 3.1 ms, FOV = 240 mm² × 240 mm², matrix = 128 × 128, slice thickness = 5 mm, bandwidth = 15.63 kHz. The MT saturation pulse was set to 4 ms width Fermi pulse with flip = 600° (B₁ = 1.95 μT). Forty-one equidistant frequency offsets between 5 and -5 ppm and an additional S₀ image were acquired. Z-spectra were corrected for B₀ inhomogeneity using a water saturation shift referencing map (WASSR) with the saturation power and time are 0.1 μT and 20 ms, respectively.