title: Live augmented reality: a new visualization method for laparoscopic surgery using continuous volumetric computed tomography.
abstract: BACKGROUND
  Current laparoscopic images are rich in surface detail but lack information on deeper structures. This report presents a novel method for highlighting these structures during laparoscopic surgery using continuous multislice computed tomography (CT). This has resulted in a more accurate augmented reality (AR) approach, termed "live AR," which merges three-dimensional (3D) anatomy from live low-dose intraoperative CT with live images from the laparoscope.
  
  
  METHODS
  A series of procedures with swine was conducted in a CT room with a fully equipped laparoscopic surgical suite. A 64-slice CT scanner was used to image the surgical field approximately once per second. The procedures began with a contrast-enhanced, diagnostic-quality CT scan (initial CT) of the liver followed by continuous intraoperative CT and laparoscopic imaging with an optically tracked laparoscope. Intraoperative anatomic changes included user-applied deformations and those from breathing. Through deformable image registration, an intermediate image processing step, the initial CT was warped to align spatially with the low-dose intraoperative CT scans. The registered initial CT then was rendered and merged with laparoscopic images to create live AR.
  
  
  RESULTS
  Superior compensation for soft tissue deformations using the described method led to more accurate spatial registration between laparoscopic and rendered CT images with live AR than with conventional AR. Moreover, substitution of low-dose CT with registered initial CT helped with continuous visualization of the vasculature and offered the potential of at least an eightfold reduction in intraoperative X-ray dose.
  
  
  CONCLUSIONS
  The authors proposed and developed live AR, a new surgical visualization approach that merges rich surface detail from a laparoscope with instantaneous 3D anatomy from continuous CT scanning of the surgical field. Through innovative use of deformable image registration, they also demonstrated the feasibility of continuous visualization of the vasculature and considerable X-ray dose reduction. This study provides motivation for further investigation and development of live AR.
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 22 South Greene Street, Baltimore, MD 21201, USA. rshekhar@umm.edu
authors.forename: Raj
authors.initials: R
authors.lastname: Shekhar
authors.forename: Omkar
authors.initials: O
authors.lastname: Dandekar
authors.forename: Venkatesh
authors.initials: V
authors.lastname: Bhat
authors.forename: Mathew
authors.initials: M
authors.lastname: Philip
authors.forename: Peng
authors.initials: P
authors.lastname: Lei
authors.forename: Carlos
authors.initials: C
authors.lastname: Godinez
authors.forename: Erica
authors.initials: E
authors.lastname: Sutton
authors.forename: Ivan
authors.initials: I
authors.lastname: George
authors.forename: Steven
authors.initials: S
authors.lastname: Kavic
authors.forename: Reuben
authors.initials: R
authors.lastname: Mezrich
authors.forename: Adrian
authors.initials: A
authors.lastname: Park
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D010535:Laparoscopy / Q000379:methods*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*