title: Integration of indocyanine green videoangiography with operative microscope: augmented reality for interactive assessment of vascular structures and blood flow.
abstract: BACKGROUND
  Preservation of adequate blood flow and exclusion of flow from lesions are key concepts of vascular neurosurgery. Indocyanine green (ICG) fluorescence videoangiography is now widely used for the intraoperative assessment of vessel patency.
  
  
  OBJECTIVE
  Here, we present a proof-of-concept investigation of fluorescence angiography with augmented microscopy enhancement: real-time overlay of fluorescence videoangiography within the white light field of view of conventional operative microscopy.
  
  
  METHODS
  The femoral artery was exposed in 7 anesthetized rats. The dissection microscope was augmented to integrate real-time electronically processed near-infrared filtered images with conventional white light images seen through the standard oculars. This was accomplished by using an integrated organic light-emitting diode display to yield superimposition of white light and processed near-infrared images. ICG solution was injected into the jugular vein, and fluorescent femoral artery flow was observed.
  
  
  RESULTS
  Fluorescence angiography with augmented microscopy enhancement was able to detect ICG fluorescence in a small artery of interest. Fluorescence appeared as a bright-green signal in the ocular overlaid with the anatomic image and limited to the anatomic borders of the femoral artery and its branches. Surrounding anatomic structures were clearly visualized. Observation of ICG within the vessel lumens permitted visualization of the blood flow. Recorded video loops could be reviewed in an offline mode for more detailed assessment of the vasculature.
  
  
  CONCLUSIONS
  The overlay of fluorescence videoangiography within the field of view of the white light operative microscope allows real-time assessment of the blood flow within vessels during simultaneous surgical manipulation. This technique could improve intraoperative decision making during complex neurovascular procedures.
authors.affiliation: *Division of Neurosurgery, University of Arizona, Tucson, Arizona; ‡Neurosurgery Research Laboratory, University of Arizona, Tucson, Arizona; §Department of Biomedical Engineering, University of Arizona, Tucson, Arizona.
authors.forename: Nikolay L
authors.initials: NL
authors.lastname: Martirosyan
authors.forename: Jesse
authors.initials: J
authors.lastname: Skoch
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Watson
authors.forename: G Michael
authors.initials: GM
authors.lastname: Lemole
authors.forename: Marek
authors.initials: M
authors.lastname: Romanowski
authors.forename: Rein
authors.initials: R
authors.lastname: Anton
mesh_terms: D015901:Angiography, Digital Subtraction / Q000379:methods*; D000818:Animals; D001775:Blood Circulation / Q000502:physiology; D004396:Coloring Agents; D005451:Fluorescein Angiography / Q000379:methods*; D007208:Indocyanine Green; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods*; D051381:Rats; D014656:Vascular Surgical Procedures / Q000379:methods*; D014741:Video Recording / Q000379:methods
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green