Methods

Data Acquisition: MRI volume was acquired from a 36 year old male subject with a Phillip Gyroscan ACS 1.5T MRI scanner. Using a three dimensional spoiled GRASS acquisition, T1 weighted slices (TR/TE =18ms/10ms and flip angle = 30) at 1 mm distance were collected over the whole brain. Using an automatic registration method [3], T1 images from volumetric data acquired in native space were transformed into Talairach space. The registered image was corrected for intensity non-uniformity [4] and a three-dimensional image was constructed using an algorithm created in our laboratory. Segmentation was done using a locally available image analysis package 'Display'.

2#2

The boundaries for each structure was manually chosen based on the anatomy of the brain as described in various atlases [5][6] . Using this parcellation scheme, we have segmented the MRI into 90 identified structures (44 bilaterally). In addition, a 3D surface rendered image of the MRI was created and colour coded with the labels of individual gyri in order to facilitate the location of the structures (Fig 2 and Fig. 3). The coordinates of each structure can be related to other brain volumes since the segmentation was done in stereotaxic space.

3#3