2.2. MRI Processing and Analysis

Patients after SA and HC went through the same MRI protocol, which consisted of T2-weighted (T2W)/FLAIR axial (TR 9000ms, TE 89ms) and T2W/fl2d/hemo axial (TR 800ms, TE26ms) sequences in order to rule out the pathologies as lesions and hemorrhage. Image data were collected using 1.5 Tesla (T) Siemens Avanto (Siemens, Munich, Germany) scanner with a standard quadrature head volume coil. Head movement was prevented by pads inside the coil. Whole-brain T1-weighted (T1W) mpr/p2/iso axial (TR 1900ms, TE 3.35ms, 1 mm slice thickness) sequence was used for volumetric measurement. During brain MRI, the patients had no suicidal ideation.

All MRI data were subject to strict quality control procedures. First, the radiologists checked T1W images for artefacts. If the latter met the requirements, they were converted to mgz files. Brain cortical thickness and grey- and white-matter volumes were measured using FreeSurfer 6.0 image analysis suite (http://surfer.nmr.mgh.harvard.edu/; accessed on 22 September 2018). This automatic reconstruction technique outweighs standard brain volume measurement due to the fact that it investigates across the whole brain and can locate changes which may be very small or do not match usual anatomical subdivisions. The FreeSurfer software constructs a three-dimensional representation of the cortical surface and volume quantifications applying image intensities and continuity data from the entire MRI volume to create reproductions of the border between gray and white matter and pial surface [4]. FreeSurfer’s Desikan–Killiany atlas was used to define regions of interest for the brain cortex: the frontal cortex contained 11 regions, temporal cortex—9 regions [14,15]. Freesurfer‘s automated segmentation of hippocampal substructures divided the hippocampus into 13 subfields [16].