title: Quantification of fluorescence angiography in a porcine model.
abstract: OBJECTIVE
  There is no consensus on how to quantify indocyanine green (ICG) fluorescence angiography. The aim of the present study was to establish and gather validity evidence for a method of quantifying fluorescence angiography, to assess organ perfusion.
  
  
  METHODS
  Laparotomy was performed on seven pigs, with two regions of interest (ROIs) marked. ICG and neutron-activated microspheres were administered and the stomach was illuminated in the near-infrared range, parallel to continuous recording of fluorescence signal. Tissue samples from the ROIs were sent for quantification of microspheres to calculate the regional blood flow. A software system was developed to assess the fluorescent recordings quantitatively, and each quantitative parameter was compared with the regional blood flow. The parameter with the strongest correlation was then compared with results from an independently developed algorithm, to evaluate reproducibility.
  
  
  RESULTS
  A strong correlation was found between regional blood flow and the slope of the fluorescence curves (ROI I: Pearson r = 0.97, p < 0.001; ROI II: 0.96, p < 0.001) as the normalized slope (ROI I: Pearson r = 0.92, p = 0.004; ROI II: r = 0.96, p = 0.001). There was acceptable correlation of the slope of the curve between two independently developed algorithms (ROI I+II: Pearson r = 0.83, p < 0.001), and good resemblance was found with the Bland-Altman method, with no proportional bias.
  
  
  CONCLUSIONS
  Perfusion assessment with quantitative indocyanine green fluorescence angiography is not only feasible but easy to perform with commercially available equipment and readily accessible software.
authors.affiliation: Department of Surgical Gastroenterology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark. nikolajnerup@gmail.com.
authors.forename: Nikolaj
authors.identifier: http://orcid.org/0000-0003-4066-2925
authors.initials: N
authors.lastname: Nerup
authors.affiliation: Center for Surgical Science (CSS), Zealand University Hospital, Lykkebækvej 1, 4600, Køge, Denmark.
authors.forename: Helene Schou
authors.initials: HS
authors.lastname: Andersen
authors.affiliation: Department of Surgical Gastroenterology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark.
authors.forename: Rikard
authors.initials: R
authors.lastname: Ambrus
authors.affiliation: Department of Surgical Gastroenterology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark.
authors.forename: Rune Broni
authors.initials: RB
authors.lastname: Strandby
authors.affiliation: Marine Biological Section, University of Copenhagen, Strandpromenaden 5, 3000, Elsinore, Denmark.
authors.forename: Morten Bo Søndergaard
authors.initials: MBS
authors.lastname: Svendsen
authors.affiliation: Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen Ø, Denmark.
authors.forename: Mads Holst
authors.initials: MH
authors.lastname: Madsen
authors.affiliation: Department of Surgical Gastroenterology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark.
authors.forename: Lars Bo
authors.initials: LB
authors.lastname: Svendsen
authors.affiliation: Department of Surgical Gastroenterology, Copenhagen University Hospital Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark.
authors.forename: Michael Patrick
authors.initials: MP
authors.lastname: Achiam
mesh_terms: D000465:Algorithms; D000818:Animals; D004396:Coloring Agents; D004064:Digestive System / Q000098:blood supply* / Q000000981:diagnostic imaging*; D005451:Fluorescein Angiography; D007208:Indocyanine Green; D007813:Laparotomy; D023421:Models, Animal; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D013552:Swine
chemical_list: D004396:Coloring Agents; D007208:Indocyanine Green
keywords: Anastomotic perfusion; Fluorescence angiography; Fluorescence guided surgery; Indocyanine green (ICG); Microcirculation; Quantitative perfusion assessment