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.
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.
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.