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James P. O'Shea
Graduate Student

University of California, Berkeley
Vision Science Program
Visualization Lab
Banks Lab
505 Minor Hall
University of California, Berkeley
Berkeley, CA 94720-2020

joshea (at) cs.berkeley.edu

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Using surface normals to localize electrodes placed during neurosurgery

James P. O’Shea, William M. Wells, Alexandra J. Golby

Clinical and research neurosurgical studies involving the use of intracranial electroencephalography and cortical stimulation depend critically on accurate localization of electrodes. Neuronavigation tracking probes enable surgeons to record the position of exposed electrodes, but they cannot be used to reliably measure subdural contacts placed under the dura and beyond the extent of the craniotomy. We describe an algorithm to estimate the position of these inaccessible sites using the patient's preoperative structural MRI data. After generating a model of the cortical surface, our algorithm estimates surface normals at the sites of accessible electrodes, establishes the orientation of the electrode strips, and then extrapolates the position of adjacent contacts based on the known inter-electrode distance. We performed validation using a patient dataset consisting of 37 electrodes placed on the cortical surface during surgery.

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Results from our algorithm. Top: Intraoperative locations of electrodes recorded by the neuronavigation system and passed as input to our algorithm. The neurosurgeon approximated the location of the six anterior sites because they were inaccessible to the tracking probe. Middle: The results of our algorithm for the same strip. Bottom: Validation data as recorded by a postoperative CT.


Research Paper: PDF

Using surface normals to localize electrodes placed during neurosurgery
James P. O’Shea, William M. Wells, Alexandra J. Golby
IEEE International Symposium on Biomedical Imaging 2006
April 2006. 331-334.