Align images

We used acpcdetect module from the Automatic Registration Tool (ART) (V2011-4-5, Website download https://www.nitrc.org/projects/art)  to align the T1-weighted image so that the anterior commissure (AC) and posterior commissure (PC) lie along a horizontal plane with the mid-sagittal plant passing through each landmark. The module uses a rigid-body transformation for this alignment.