Sonata scanner

All subjects (meditators/controls) were scanned on the same site, using the same scanner, and following the same scanning protocol. Specifically, magnetic resonance images were acquired on a 1.5 Tesla Siemens Sonata scanner (Erlangen, Germany) using an 8-channel head coil and a T1-weighted MPRAGE sequence (1900 ms TR, 4.38 ms TE, 15° flip angle, 160 contiguous sagittal slices, 256 mm × 256 mm FOV, 1 mm × 1 mm × 1 mm voxel). The obtained structural brain images were then corrected for intensity inhomogeneities and linearly transferred into a standard space using six-parameter (rigid-body) normalizations, as previously detailed (Luders et al., 2013b (link)).

Images were obtained using a 3-T Siemens Sonata scanner. Functional imaging data were analysed using FEAT 6.0, part of FSL (FMRIB Software Library; fmrib.ox.ac.ul/fsl) with Z>2.3 and P<0.05, including multiple-comparison corrections. T₂*-weighted functional data were acquired for a whole-brain field of view (64 × 64 × 40 matrix, 45 slices, voxel resolution 3 mm³, gap 1.5 mm, repetition time=3000 ms, echo time=30 ms, flip angle=90^o). Field maps were acquired using a dual-echo two-dimensional gradient echo sequence with echos at 5.19 and 7.65 ms, and a repetition time of 500 ms. High-resolution T₁-weighted images were acquired for subject alignment, using an MPRAGE sequence (174 × 192 × 192 matrix, voxel resolution 1 mm³, repetition time=2040 ms, echo time=4.7 ms, inversion time=900 ms).

All eight participants had baseline ¹⁸F-AZD4694 and ¹⁸F-THK5351 PET scans to quantify brain amyloid and PHF load, respectively. A second ¹⁸F-THK5351 scan was conducted 1 week later, 1 h after an oral dose of 10 mg selegiline. Participants were also invited to undergo an optional third ¹⁸F-THK5351 PET scan 10 days after the selegiline administration. Each ¹⁸F-THK5351 acquisition consisted of dynamic images (4 × 5 min) acquired at 50–70 min after intravenous bolus injection. The mean ± standard deviation injected radioactivity of ¹⁸F-THK5351 was 6.6 ± 0.3 mCi for the baseline scan, 6.7 ± 0.4 mCi for the post-selegiline scan, and 6.9 ± 0.4 mCi for the third scan. ¹⁸F-AZD4694 acquisition consisted of dynamic images (6 × 5 min) acquired at 40–70 min after intravenous bolus injection of ¹⁸F-AZD4694. The injected radioactivity of ¹⁸F-AZD4694 was 6.3 ± 0.3 mCi. A 6-min transmission scan was acquired at the end of each PET scan. All PET scans were performed using the Siemens High Resolution Research Tomograph (HRRT). A magnetic resonance imaging (MRI) anatomical scan was also performed for all patients using the 1.5 T Siemens Sonata scanner for co-registration purposes.

T1-weighted high resolution MRI images were obtained with a FLASH 3D sequence on a 1.5 Tesla Siemens Sonata scanner acquiring 192 sagittal slices (repetition time = 15 ms, echo time = 5 ms, Flip Angle = 30°) and using a standard 4-channel head coil. The original DICOM images were converted into the Nifti format using Dcm2Nii (MRIcroN). The CAT12- toolbox was used for preprocessing and VBM analyses (http://www.neuro.uni-jena.de/cat/), as it provides substantial improvements relative to the standard algorithms of the Statistical Parametric Mapping software (SPM) (for e.g. segmentation without tissue priors, integration of Dartel normalization). T1 data segmentation was performed and resulting probability maps for Gray Matter (GM) and White Matter (WM) were spatially normalized into MNI space using the default toolbox settings. Smoothing was applied with a standard Gaussian Kernel of 8 mm. Implicit masking was applied using an absolute threshold of 0.2.

Images were acquired at the “CERMEP-Imagerie du vivant” imaging center of Lyon (France) on a 1.5T Siemens Sonata scanner with a standard 8-channel head coil. For fMRI, echo planar T2*-weighted axial images were acquired with the following parameters: 26 interleaved slices; repetition time = 2500 ms; echo time = 60 ms; field of view = 240 mm²; flip angle = 90°; matrix = 64 × 64 (voxel size: 3.75 × 3.75 × 4 mm). Manual shimming was performed on the whole brain to improve the local field homogeneity and minimize susceptibility artifacts. Before the first fMRI session, a 3D T1-weighted anatomical scan was acquired (176 axial slices; repetition time = 1970 ms; echo time = 3.93 ms; field of view = 256 mm²; voxel size = 1 mm³).

Two sets of structural MRI images were acquired for each participant using a 3-T Siemens Sonata scanner (Malvern, PA, USA) with a high-resolution 3-D T1-weighted magnetization-prepared 180° radio-frequency pulses and rapid gradient-echo (MP-RAGE) sequence optimized for gray–white matter contrast differentiation. The two sets of scans were registered and averaged. The cortical white matter was segmented and the border between gray and white matter was tessellated, providing a representation of the cortical surface with ~150,000 vertices per hemisphere (Fischl et al., 2001 (link)). The folded tessellated surface was then “inflated” in order to unfold cortical sulci, thereby providing a convenient format for visualizing cortical activation patterns (Fischl et al., 1999 (link)).