Augmented reality-guided neurosurgery: accuracy and intraoperative application of an image projection technique.
OBJECTIVE
An augmented reality system has been developed for image-guided neurosurgery to project images with regions of interest onto the patient's head, skull, or brain surface in real time. The aim of this study was to evaluate system accuracy and to perform the first intraoperative application.


METHODS
Images of segmented brain tumors in different localizations and sizes were created in 10 cases and were projected to a head phantom using a video projector. Registration was performed using 5 fiducial markers. After each registration, the distance of the 5 fiducial markers from the visualized tumor borders was measured on the virtual image and on the phantom. The difference was considered a projection error. Moreover, the image projection technique was intraoperatively applied in 5 patients and was compared with a standard navigation system.


RESULTS
Augmented reality visualization of the tumors succeeded in all cases. The mean time for registration was 3.8 minutes (range 2-7 minutes). The mean projection error was 0.8 ± 0.25 mm. There were no significant differences in accuracy according to the localization and size of the tumor. Clinical feasibility and reliability of the augmented reality system could be proved intraoperatively in 5 patients (projection error 1.2 ± 0.54 mm).


CONCLUSIONS
The augmented reality system is accurate and reliable for the intraoperative projection of images to the head, skull, and brain surface. The ergonomic advantage of this technique improves the planning of neurosurgical procedures and enables the surgeon to use direct visualization for image-guided neurosurgery.
Department of Neurosurgery, Clinic of Köln-Merheim, University of Witten-Herdecke, Köln, Germany.
Leila
L
Besharati Tabrizi
Department of Neurosurgery, Clinic of Köln-Merheim, University of Witten-Herdecke, Köln, Germany.
Mehran
M
Mahvash
D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D007432:Intraoperative Period; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*; D009493:Neurosurgery / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D016896:Treatment Outcome; D014584:User-Computer Interface
HMD = head-mounted display; ROI = region of interest; augmented reality–guided neurosurgery; diagnostic and operative techniques; intraoperative application; neuronavigation; projection accuracy