Multimodal Neuroimaging Protocol for Resting-State Evaluation

The participants were scanned in a 3T PET/MR Siemens Biograph mMR scanner with a vendor-supplied 16-channel head coil. They were instructed to fast for six hours prior to the scan session. After the intravenous injection of on average 102 ± 5 (SD) MBq of 18 F-FDG, the participants stayed comfortably in a quiet, dimly lit room, with closed eyes. Reconstructed PET images (30–60 min post-injection) had a voxel size of 1.04 × 1.04 × 2.03 mm³. Anatomical T1-weighted images were acquired with a magnetization‐prepared rapid gradient‐echo (MP‐RAGE) sequence with a voxel size of 1.0 × 1.0 × 1.0 mm³. DWI was performed using a single-shot EPI sequence of voxel size 2 × 2 × 2 mm³, with 30 diffusion directions with b = 800 s/mm² and one volume with b = 0 s/mm². For the fMRI acquisition, which lasted 8 min, participants were instructed to stay awake, close their eyes and think of nothing in particular. 212 volumes were acquired using a Prospective Acquisition Correction EPI sequence with voxel size of 3.0 × 3.0 × 3.0 mm³. An ultra-short echo time sequence was acquired for attenuation correction of the PET data. A dual echo gradient echo sequence was acquired to correct the DWI images for susceptibility induced distortions. Details of the PET and MR acquisitions are given in the supplementary material to our recent article.^{39 (link)}