title: Image-guided transorbital procedures with endoscopic video augmentation.
abstract: OBJECTIVE
  Surgical interventions to the orbital space behind the eyeball are limited to highly invasive procedures due to the confined nature of the region along with the presence of several intricate soft tissue structures. A minimally invasive approach to orbital surgery would enable several therapeutic options, particularly new treatment protocols for optic neuropathies such as glaucoma. The authors have developed an image-guided system for the purpose of navigating a thin flexible endoscope to a specified target region behind the eyeball. Navigation within the orbit is particularly challenging despite its small volume, as the presence of fat tissue occludes the endoscopic visual field while the surgeon must constantly be aware of optic nerve position. This research investigates the impact of endoscopic video augmentation to targeted image-guided navigation in a series of anthropomorphic phantom experiments.
  
  
  METHODS
  A group of 16 surgeons performed a target identification task within the orbits of four skull phantoms. The task consisted of identifying the correct target, indicated by the augmented video and the preoperative imaging frames, out of four possibilities. For each skull, one orbital intervention was performed with video augmentation, while the other was done with the standard image guidance technique, in random order.
  
  
  RESULTS
  The authors measured a target identification accuracy of 95.3% and 85.9% for the augmented and standard cases, respectively, with statistically significant improvement in procedure time (Z=-2.044, p=0.041) and intraoperator mean procedure time (Z=2.456, p=0.014) when augmentation was used.
  
  
  CONCLUSIONS
  Improvements in both target identification accuracy and interventional procedure time suggest that endoscopic video augmentation provides valuable additional orientation and trajectory information in an image-guided procedure. Utilization of video augmentation in transorbital interventions could further minimize complication risk and enhance surgeon comfort and confidence in the procedure.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235.
authors.forename: Michael P
authors.initials: MP
authors.lastname: DeLisi
authors.affiliation: Department of Neurological Surgery, Vanderbilt University, Nashville, Tennessee 37235 and Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee 37235.
authors.forename: Louise A
authors.initials: LA
authors.lastname: Mawn
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235 and Department of Neurological Surgery, Vanderbilt University, Nashville, Tennessee 37235.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Galloway
mesh_terms: D002138:Calibration; D006801:Humans; D008954:Models, Biological; D009915:Orbit / Q000601:surgery*; D019047:Phantoms, Imaging; D025321:Surgery, Computer-Assisted; D013997:Time Factors; D020535:Video-Assisted Surgery / Q000295:instrumentation / Q000379:methods*