2.4 MRI acquisition
MRI scans were conducted on a Siemens Magnetom Verio 3T scanner (Siemens
Medical Solutions, Erlangen, Germany). A 12-element Head Matrix coil
allowed the use of Generalized Autocalibrating Partially Parallel
Acquisition (GRAPPA) technique to accelerate acquisitions (PAT factor of
2 was used). Sequence parameters of the 2D Dual Echo TSE (Turbo Spin
Echo) sequence were optimized so that “whisper” gradient mode could be
used in order to reduce acoustic noise during the scan. Slice thickness
was 1mm in order to acquire isotropic 1.0 × 1.0 × 1.0 mm voxels. TR time
of 12070 ms and effective TE times of 13 ms and 102 ms were used to
produce both PD-weighted and T2- weighted images from the same
acquisition. The total number of slices was 128. T1-weighted 3D MPRAGE
(Magnetization Prepared Rapid Acquisition Gradient Echo) sequence with
isotropic 1.0 × 1.0 × 1.0 mm voxels was used for anatomical imaging as
well. The sequences included DTI imaging (details not reported here).
Functional MRI consisted of 120 volumes with voxel size 3.0 × 3.0 × 3.0
mm, TR 3000 ms, TE 30 ms, flip angle of 80 ° and 42 axial slices without
gaps. Prior to fMRI acquisition, all infants had slept during the 45–50
min required for structural scanning. The total duration of the complete
scanning protocol did not exceed 60 min.