Fig. 1.

Illustration of SPM12 tissue segmentation results and manually edited intracranial mask: (a) Original T1-weighted MRI [miriad_188],⁵ (b) grey matter, (c) white matter, (d) cerebrospinal fluid; overlaid on each image in red is a contour showing the outline of the intracranial mask after inverse spatial normalisation (i.e. warping from MNI to native space). It can be seen in (d) that the mask excludes some voxels incorrectly segmented as the CSF, and in (c) that the mask achieves a consistent anatomically-defined inferior cut-off, independent of the acquired field-of-view.