Software - PD/T2 Skullstrip
This algorithm creates a joint histogram of the PD and T2 images to aid in identifying brain voxels. In the histogram the brain region is typically represented by a globular bulge either adjacent to or bisected by a curved region derived from non-brain.
When the brain region is adjacent to but distinct from the non-brain, this can be automatically detected. In the other cases, user intervention is required to designate the desired area of the histogram. This involves drawing a single contour to surround the brain region.
In either instance, once the brain region of the histogram is identified, the PD and T2 images are stripped based on the voxels identified from the histogram segmentation. Finally some morphological operations involving hole filling and erosions remove minor extraneous tissue.
The following set of figures illustrates the sequence of stages in the double spin echo skullstrip.
Figure Automated T2 image skull stripping. Left: unstripped image. Middle: stripped image after automated stage and minor user cleanup. Right: manual selection of brain tissue from the histogram.