A novel method is presented to automatically extract the midsagittal plane (MSP) from volumetric MR images. The MSP
which generally approximates the interhemispheric fissure is the plane separating both hemispheres. It is meaningful for
the brain segmentation, registration, quantification and pathology detection especially in Talairach space. The algorithm
works based on the theory of the symmetry principal axis, the local searching method and minimizing the local
symmetry coefficient. The proposed algorithm is validated on 20 T2-weighted MR data sets, which indicates that a clear
MSP image can be extracted in the presence of relatively bigger distance error or angular deviation. This fully automatic
algorithm is potentially useful in the clinical application and for research.