Stereopsis-Guided Brain Shift Compensation

H. Sun (advisor: H. Farid and K. Paulsen)

Ph.D. Dissertation, Thayer School of Engineering, Dartmouth College, 2005

Dissertation (pdf)    Bibtex

Brain deformation models have proven to be a powerful tool in compensating for soft tissue deformation during image-guided neurosurgery. The accuracy of these models can be improved by incorporating intraoperative measurements of brain motion. We have designed and implemented a passive intraoperative stereo vision (iSV) system capable of estimating the 3-D shape of the surgical scene in near real-time. The motion of the estimated cortical surface is then tracked over time. This cortical motion is used to guide a full brain model, which subsequently updates a preoperative MR volume. We have found that the iSV system is accurate to within approximately 1mm. Executing on a 1.1 GHz Pentium machine, the 3-D estimation from a stereo pair of 1024 x 768 resolution images requires approximately 60 seconds of computation. Based on data from representative clinical cases, we show that stereopsis guidance improves the accuracy of brain shift compensation both at and below the cortical surface. Specifically, we report an average error reduction of 3.7mm relative to the model estimate without using intraoperative data. In addition, advantages of our iSV system include its fast acquisition rates, predominantly automated steps, and overall accuracy. These characteristics allow us to capture other important cortical behavior such as the tissue resection and the pulsatile motion of the cortical surface.