title: Microscope-integrated quantitative analysis of intraoperative indocyanine green fluorescence angiography for blood flow assessment:  first experience in 30 patients.
abstract: BACKGROUND
  Intraoperative measurements of cerebral blood flow are of interest during vascular neurosurgery. Near-infrared indocyanine green (ICG) fluorescence angiography was introduced for visualizing vessel patency intraoperatively. However, quantitative information has not been available.
  
  
  OBJECTIVE
  To report our experience with a microscope with an integrated dynamic ICG fluorescence analysis system supplying semiquantitative information on blood flow.
  
  
  METHODS
  We recorded ICG fluorescence curves of cortex and cerebral vessels using software integrated into the surgical microscope (Flow 800 software; Zeiss Pentero) in 30 patients undergoing surgery for different pathologies. The following hemodynamic parameters were assessed: maximum intensity, rise time, time to peak, time to half-maximal fluorescence, cerebral blood flow index, and transit times from arteries to cortex.
  
  
  RESULTS
  For patients without obvious perfusion deficit, maximum fluorescence intensity was 177.7 arbitrary intensity units (AIs; 5-mg ICG bolus), mean rise time was 5.2 seconds (range, 2.9-8.2 seconds; SD, 1.3 seconds), mean time to peak was 9.4 seconds (range, 4.9-15.2 seconds; SD, 2.5 seconds), mean cerebral blood flow index was 38.6 AI/s (range, 13.5-180.6 AI/s; SD, 36.9 seconds), and mean transit time was 1.5 seconds (range, 360 milliseconds-3 seconds; SD, 0.73 seconds). For 3 patients with impaired cerebral perfusion, time to peak, rise time, and transit time between arteries and cortex were markedly prolonged (>20, >9 , and >5 seconds). In single patients, the degree of perfusion impairment could be quantified by the cerebral blood flow index ratios between normal and ischemic tissue. Transit times also reflected blood flow perturbations in arteriovenous fistulas.
  
  
  CONCLUSIONS
  Quantification of ICG-based fluorescence angiography appears to be useful for intraoperative monitoring of arterial patency and regional cerebral blood flow.
authors.affiliation: Klinik für Neurochirurgie, Heinrich-Heine-Universität, Düsseldorf, Germany. marcelalexander.kamp@uni-duesseldorf.de
authors.forename: Marcel A
authors.initials: MA
authors.lastname: Kamp
authors.forename: Philipp
authors.initials: P
authors.lastname: Slotty
authors.forename: Bernd
authors.initials: B
authors.lastname: Turowski
authors.forename: Nima
authors.initials: N
authors.lastname: Etminan
authors.forename: Hans-Jakob
authors.initials: HJ
authors.lastname: Steiger
authors.forename: Daniel
authors.initials: D
authors.lastname: Hänggi
authors.forename: Walter
authors.initials: W
authors.lastname: Stummer
mesh_terms: D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology; D002536:Cerebral Arteries / Q000503:physiopathology / Q000601:surgery; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004396:Coloring Agents; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods*; D006801:Humans; D007208:Indocyanine Green; D007431:Intraoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods*; D008875:Middle Aged; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014656:Vascular Surgical Procedures / Q000379:methods*
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green