A brain template is used for spatial normalization of each individual brain MRI to a standard stereotaxic space. The Montreal Neurological Institute (MNI) has created a brain template which was generated from 305 MRI volumes of normal European subjects. However, Zilles et al. showed inter-ethnic differences in hemispheric shape. In order to minimize the distortion made by warping to the template, a brain template for Taiwanese is necessary. In this work, we plan to build up a brain MRI database for each generation and gender. Then, a Taiwanese brain template will be constructed from the database.
The first thing of constructing a brain template is to map all brain subjects to the same stereotaxic coordinate space. A reference volume plays the role of the standard coordinate space. In order to use anterior commissure(AC) as origin and the line cross anterior commissure and posterior commissure(PC), called the AC-PC line, as the mapping axis, mid-sagittal plane (MSP) determination is required. Finally, we average all subjects which are now in the same stereotaxic coordinate space and take this mean brain as the template brain.
By using different ethnic brain as reference subject, the results show that a Taiwanese reference subject is more suitable than a western reference subject. We choose different ethnic brains as reference subject. One of the reference subjects is the Talairach Brain, and the other is subject A.
We claim that a Taiwanese reference subject is more suitable than a western reference subject by observing the measured distance of mid-AC-PC-point of ground truth to the green AC-PC line which is transformed from reference subject. When using Talairach Brain as reference subject, the distance is 2.816 mm. On the other hand, when using subject A, the distance is only 0.0092863 mm.
Figure 1 : This is the brain template which created by using Taiwanese subject A as reference subject.