Automated detection of mid-sagittal plane in MR images of the head

A fully automated and robust method is presented for dividing NM 3D images of the human brain into two hemispheres. The method is developed specifically to deal with pathologically affected brains or brains in which the longitudinal fissure (LF) is significantly widened due to ageing or atrophy associated with neuro-degenerative processes. To provide a definitive estimate of the mid-sagittal plane, the method combines longitudinal fissure lines detected in both axial and coronal slices of T1-weighted MR images and then fit these lines to a 3D plane. The method was applied to 36 brain MR image data sets (15 of them arising from subjects with probable Alzheimer's disease) all exhibiting some degrees of widened fissures and/or significant asymmetry due to pathology. Visual inspection of the results revealed that the separation was highly accurate and satisfactory. In some cases (5 in total), there were minor degrees of asymmetry in the posterior fossa structures despite successful splitting of cerebral cortex.