Skyra vd13

All subjects underwent the same imaging protocol. A 3-T Skyra VD13 (Siemens Healthcare, Erlangen, Germany) with a 32-channel receive coil was used for MRI data acquisition. An anatomical three-dimensional high-resolution T1-weighted Magnetization Prepared Rapid Acquisition Gradient Echo (MPRAGE) image was acquired with the following specification (van Niftrik et al. 2018 (link)): ACPC line plus 20° (on a sagittal image), voxel size 0.8 × 0.8 × 1.0 mm³, field of view 230 × 230 × 176 mm³, scan matrix of 288 × 288 × 176, TR/TE/TI 2200/5.14/900 ms, flip angle 8°.

MRI data were acquired on a 3-tesla Skyra VD13 scanner (Siemens Healthineers, Forchheim, Germany) with a 32-channel head coil. BOLD fMRI parameters and a three-dimensional (3 D) T1-weighted Magnetization Prepared Rapid Acquisition Gradient Echo (MP RAGE) image was performed in the same way as published in our previous work.^{13 (link)}
During the BOLD fMRI sequence, the carbon dioxide (CO₂) stimulus was given with a computer controlled gas blender with prospective gas targeting algorithms (RespirAct™, Thornhill Research Institute, Toronto, Canada). The RespirAct™ allows for precise targeting of arterial partial pressure CO₂ while maintaining normal levels of O₂ (iso-oxia).^{16 (link)}
During the CVR study, a standardized and controlled hypercapnic stimulus is applied (i.e. the patients´ CO₂ was increased ∼10 mmHg above their resting CO₂ value for 80 seconds).^{13 (link)}
All the acquired raw BOLD fMRI volumes were transferred to an external computer and pre-processed with SPM 12 (Statistical Parameter Mapping Software, Wellcome Department of Imaging Neuroscience, University College of London, London, UK). The BOLD fMRI volumes were processed and aligned to the T1-weighted MP RAGE image as well as smoothed with a Gaussian Kernel (for more information, see Sebök et al., 2018, Methods).^{13 (link)}