title: The accuracy and reliability of 3D CT/MRI co-registration in planning epilepsy surgery.
abstract: OBJECTIVE
  To investigate the accuracy and reliability of 3D CT/MRI co-registration technique for the localization of implanted subdural electrodes in the routine epilepsy presurgical evaluation, in so doing assess its usefulness in planning the tailored resection of epileptic focus.
  
  
  METHODS
  Four external anatomic fiducial makers were used for co-registration of volumetric pre-implant brain MRI and post-implant head CT using Curry 5.0 software in 19 epilepsy presurgical candidates. The location of subdural electrodes derived from the co-registration was compared to that obtained by intra-operative digital photographs by using gyral/sulcal patterns and cortical vasculature as anatomic markers.
  
  
  RESULTS
  The mean localization error was 4.3+/-2.5 mm in all 19 patients. However, the mean localization error was 3.1+/- 1.3 mm in 13 patients with all four reliable fiducial markers; whereas the mean localization error was 6.8+/-2.4 mm in 6 patients with two or three reliable fiducial markers.
  
  
  CONCLUSIONS
  Visualization of subdural electrode positions on a patient's cortex can be accurately performed in the routine clinical setting by 3D CT/MRI co-registration. However, the accuracy of co-registration is dependent upon having reliable surface fiducial markers. In practice, confirmation of location accuracy, such as with intra-operative digital photographs, is necessary for planning of tailored resective surgery.
  
  
  CONCLUSIONS
  The combination of 3D CT/MRI co-registration and intra-operative digital photography techniques provides a practical and effective algorithm for the localization and validation of implanted subdural electrodes.
authors.affiliation: Department of Neurology and Neurosurgery, Adult Epilepsy Center, The University of Chicago, 5841 South Maryland Ave., MC2030, Chicago, IL 60637, USA. jtao@neurology.bsd.uchicago.edu
authors.forename: James X
authors.initials: JX
authors.lastname: Tao
authors.forename: Susan
authors.initials: S
authors.lastname: Hawes-Ebersole
authors.forename: Maria
authors.initials: M
authors.lastname: Baldwin
authors.forename: Sona
authors.initials: S
authors.lastname: Shah
authors.forename: Robert K
authors.initials: RK
authors.lastname: Erickson
authors.forename: John S
authors.initials: JS
authors.lastname: Ebersole
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010347:Patient Care Planning; D010781:Photography; D011300:Preoperative Care; D012042:Registries; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult