title: Postoperative quantitative assessment of reconstructive tissue status in a cutaneous flap model using spatial frequency domain imaging.
abstract: BACKGROUND
  The purpose of this study was to investigate the capabilities of a novel optical wide-field imaging technology known as spatial frequency domain imaging to quantitatively assess reconstructive tissue status.
  
  
  METHODS
  Twenty-two cutaneous pedicle flaps were created on 11 rats based on the inferior epigastric vessels. After baseline measurement, all flaps underwent vascular ischemia, induced by clamping the supporting vessels for 2 hours (either arteriovenous or selective venous occlusions); normal saline was injected into the control flap and hypertonic-hyperoncotic saline solution was injected into the experimental flap. Flaps were monitored for 2 hours after reperfusion. The spatial frequency domain imaging system was used for quantitative assessment of flap status over the duration of the experiment.
  
  
  RESULTS
  All flaps demonstrated a significant decline in oxyhemoglobin and tissue oxygen saturation in response to occlusion. Total hemoglobin and deoxyhemoglobin were increased markedly in the selective venous occlusion group. After reperfusion and the administration of solutions, oxyhemoglobin and tissue oxygen saturation in those flaps that survived gradually returned to baseline levels. However, flaps for which oxyhemoglobin and tissue oxygen saturation did not show any signs of recovery appeared to be compromised and eventually became necrotic within 24 to 48 hours in both occlusion groups.
  
  
  CONCLUSIONS
  Spatial frequency domain imaging technology provides a quantitative, objective method of assessing tissue status. This study demonstrates the potential of this optical technology to assess tissue perfusion in a very precise and quantitative way, enabling wide-field visualization of physiologic parameters. The results of this study suggest that spatial frequency domain imaging may provide a means for prospectively identifying dysfunctional flaps well in advance of failure.
authors.affiliation: Irvine and Orange, Calif. From the Beckman Laser Institute and Medical Clinic and the Aesthetic and Plastic Surgery Institute, University of California, Irvine, and the Modulated Imaging Inc., Beckman Laser Institute Photonic Incubator.
authors.forename: Amr
authors.initials: A
authors.lastname: Yafi
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Vetter
authors.forename: Thomas
authors.initials: T
authors.lastname: Scholz
authors.forename: Sarin
authors.initials: S
authors.lastname: Patel
authors.forename: Rolf B
authors.initials: RB
authors.lastname: Saager
authors.forename: David J
authors.initials: DJ
authors.lastname: Cuccia
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Evans
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Durkin
mesh_terms: D000818:Animals; D006454:Hemoglobins / Q000032:analysis; D008297:Male; D009336:Necrosis; D055620:Optical Phenomena; D010100:Oxygen / Q000032:analysis; D010108:Oxyhemoglobins / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000098:blood supply / Q000473:pathology; D019265:Spectroscopy, Near-Infrared; D013524:Surgical Flaps / Q000098:blood supply* / Q000473:pathology
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen