title: Mutual-information-based image to patient re-registration using intraoperative ultrasound in image-guided neurosurgery.
abstract: An image-based re-registration scheme has been developed and evaluated that uses fiducial registration as a starting point to maximize the normalized mutual information (nMI) between intraoperative ultrasound (iUS) and preoperative magnetic resonance images (pMR). We show that this scheme significantly (p<0.001) reduces tumor boundary misalignment between iUS pre-durotomy and pMR from an average of 2.5 mm to 1.0 mm in six resection surgeries. The corrected tumor alignment before dural opening provides a more accurate reference for assessing subsequent intraoperative tumor displacement, which is important for brain shift compensation as surgery progresses. In addition, we report the translational and rotational capture ranges necessary for successful convergence of the nMI registration technique (5.9 mm and 5.2 deg, respectively). The proposed scheme is automatic, sufficiently robust, and computationally efficient (<2 min), and holds promise for routine clinical use in the operating room during image-guided neurosurgical procedures.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA. Songbai.Ji@Dartmouth.edu
authors.forename: Songbai
authors.initials: S
authors.lastname: Ji
authors.forename: Ziji
authors.initials: Z
authors.lastname: Wu
authors.forename: Alex
authors.initials: A
authors.lastname: Hartov
authors.forename: David W
authors.initials: DW
authors.lastname: Roberts
authors.forename: Keith D
authors.initials: KD
authors.lastname: Paulsen
mesh_terms: D000465:Algorithms; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019635:Neurosurgical Procedures / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014463:Ultrasonography