title: Comparative effectiveness and safety of image guidance systems in surgery: a preclinical randomised study.
abstract: BACKGROUND
  Over the past decade image guidance systems have been widely adopted in specialties such as neurosurgery and otorhinolaryngology. Nonetheless, the evidence supporting the use of image guidance systems in surgery remains limited. New augmented reality systems offer the possibility of enhanced operating room workflow compared with existing triplanar image displays, but recent studies have highlighted several concerns, particularly the risk of inattentional blindness and impaired depth perception. The aim of this study was to compare simultaneously the effectiveness and safety of various image guidance systems against standard surgery.
  
  
  METHODS
  In this preclinical randomised study design 50 novice surgeons were allocated to no image guidance, triplanar display, always-on solid overlay, always-on wire mesh overlay, or on-demand inverse realism overlay. Each participant was asked to identify a basilar tip aneurysm in a validated model head. The primary outcomes were time to task completion, and tool path length. The secondary outcomes were recognition of an unexpected finding (a surgical clip) and subjective depth perception (using a Likert scale).
  
  
  RESULTS
  Surgeons' time to task completion and tool path length were significantly lower in groups using any form of image guidance than in groups with no image guidance (p<0·001 and p=0·003, respectively). The tool path distance was also lower in groups using augmented reality than in those using triplanar display (p=0·010). Always-on solid overlay resulted in the greatest inattentional blindness (20% recognition of unexpected finding by all surgeons). Wire mesh and on-demand overlays mitigated but did not negate inattentional blindness, and were comparable with triplanar display (40% recognition of unexpected finding in all groups). Wire mesh and inverse realism overlays also resulted in better subjective depth perception than always-on solid overlay (p=0·031 and p=0·008, respectively).
  
  
  CONCLUSIONS
  This study suggests that new augmented reality platforms incorporating always-on wire mesh and on-demand inverse realism might improve surgical performance, at least in novice surgeons. All image display modalities, including existing triplanar display, carry a risk of inattentional blindness.
  
  
  BACKGROUND
  Wellcome Trust.
authors: Hamlyn Centre, Imperial College London, London, UK; Department of Neurosurgery, Imperial College Healthcare NHS Trust, London, UK. Electronic address: hani.marcus10@imperial.ac.uk.
authors: Hani J
authors: HJ
authors: Marcus
authors: Hamlyn Centre, Imperial College London, London, UK.
authors: Philip
authors: P
authors: Pratt
authors: Hamlyn Centre, Imperial College London, London, UK.
authors: Archie
authors: A
authors: Hughes-Hallett
authors: Hamlyn Centre, Imperial College London, London, UK.
authors: Thomas P
authors: TP
authors: Cundy
authors: Faculty of Medicine, Imperial College London, London, UK.
authors: Adam P
authors: AP
authors: Marcus
authors: Hamlyn Centre, Imperial College London, London, UK.
authors: Guang-Zhong
authors: GZ
authors: Yang
authors: Hamlyn Centre, Imperial College London, London, UK.
authors: Ara
authors: A
authors: Darzi
authors: Department of Neurosurgery, Imperial College Healthcare NHS Trust, London, UK.
authors: Dipankar
authors: D
authors: Nandi