Registration techniques for the analysis of the brain shift in neurosurgery

The brain shift is a phenomenon that occurs during surgical operations on t he opened head. It is a deformation of the brain which prohibits exact navi gation with pre-operatively acquired tomographic scans since correlation be tween the image data and the actual anatomical situation invalidates quickl y after opening the skull. In order to analyze the brain shift nonlinear re gistration of two data sets is performed. Thereby, one data set is obtained before and the other during the operation with an open magnetic resonance scanner. Using registration based on deformable surfaces, models of the pre - and the intra-operative brain are obtained. After efficient distance calc ulation color encoding of the models gives quantitative information. For fu rther anatomical orientation these models are integrated into a representat ion of the data produced with direct volume rendering. Additionally, we sug gest a voxel-based approach based on maximizing mutual information. This ac counts for deformations of deeper lying structures considering the volume. Adaptively subdividing the data into piecewise linear patches and using 3D texture mapping, fast evaluation of the non-linear deformation is achieved. (C) 2000 Elsevier Science Ltd. All rights reserved.