All subjects were scanned with a 3.0 Tesla MR scanner (Trio, Siemens Magnetom, Erlangen, Germany, with an 8-channel phase array head coil) to obtain high resolution T1w and T2w images. A magnetization-prepared rapid acquisition gradient echo sequence was used to obtain T1w images with repetition time/echo time=1,540/2.34 ms, field of view=256 × 256, slice thickness=1 mm (with no gap), and slice number=176. A 3D T2w Sampling Perfection with Application Optimized Contrast using Different Angle Evolution (SPACE) sequence was used to obtain T2w images with repetition time/echo time=2,500/316 ms and the same spatial resolution settings as T1w images. All T1w and T2w images were inspected offline and deemed free of severe motion artifacts or any major structural abnormalities (except for two subjects from Study 2 who were excluded). T1w/T2w ratio maps for each subject then were generated using a similar method proposed by Glasser et al.19 (link) Namely, T1w and T2w images were co-registered using a rigid registration and then the T1w/T2w ratio maps were obtained by simply dividing the T1w image by the T2w image at each voxel. The T1w/T2w value at each voxel was multiplied by 100 to obtain values for robust image analysis.