M Oghabian - Medical Physics Department, / Research Center for Sciences and Technology, Tehran University of Medical Sciences, Tehran, Iran
P Kaboli - Research Center for Sciences and Technology, / Department of Radiology, Tehran University of Medical Sciences, Tehran, Iran
S Sarkar - Medical Physics Department, / Research Center for Sciences and Technology, Tehran University of Medical Sciences, Tehran, Iran

Although, most of the abnormal structures of human brain do not alter the shape of outer envelope of brain (surface), some abnormalities can deform the surface extensively. However, this may be a major problem in a surface-based registration technique, since two nearly identical surfaces are required for surface fitting process. A type of verification known as the circularity check for the shape of the detected head contours was defined based on the curvature measurement. Any unacceptable deformity (or hole) existing in the brain surface can be detected by the circularity check and 'reformed' by a type of interpolation process. Two techniques were suggested to 'reform' the abnormal regions and holes on the surfaces: one based on median filtering and another based on contour reflection.

Medical image analysis, Surface fitting, Contour detection, Curvature