title: Intraoperative Hemifacial Composite Flap Perfusion Assessment Using Spatial Frequency Domain Imaging: A Pilot Study in Preparation for Facial Transplantation.
abstract: BACKGROUND
  Vascularized composite allotransplantation represents an important advancement in the field of reconstructive microsurgery and has continued to increase in popularity. The significant clinical morbidity associated with flap failure represents an important barrier to even more widespread use of these techniques. Early identification of vascular compromise has been associated with a higher salvage rate, yet most surgeons rely only on clinical assessment intraoperatively. Spatial frequency domain imaging (SFDI) presents a noncontact, objective measurement of tissue oxygenation over a large field of view. This study aims to evaluate the use of SFDI technology in hemifacial composite flap compromise as could occur during facial transplant.
  
  
  METHODS
  Six composite hemifacial flaps were created in three 35-kg Yorkshire pigs and continuously imaged using SFDI before, during, and after 15-minute selective vascular pedicle occlusion. Arterial and venous clamping trials were performed for each flap. Changes in oxyhemoglobin concentration, deoxyhemoglobin concentration, and total hemoglobin were quantified over time.
  
  
  RESULTS
  The SFDI successfully measured changes in oxygenation parameters in all 6 composite tissue flaps. Significant changes in oxyhemoglobin, deoxyhemoglobin, and total hemoglobin were seen relative to controls. Early and distinct patterns of alteration were noted in arterial and in venous compromise relative to one another.
  
  
  CONCLUSIONS
  The need for noninvasive, reliable assessment of composite tissue graft viability is apparent, given the morbidity associated with flap failure. The results of this study suggest that SFDI technology shows promise in providing intraoperative guidance with regard to pedicle vessel integrity during reconstructive microsurgery.
authors.affiliation: From the *Division of Plastic and Reconstructive Surgery, Department of Surgery, †Division of Hematology and Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA; ‡Division of Cancer Diagnostics and Therapeutics, Hokkaido University Graduate School of Medicine, Sapporo, Japan; §Department of Biomedical Engineering, Boston University; ∥Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston; and ¶Curadel, LLC, Worcester, MA.
authors.forename: Christina R
authors.initials: CR
authors.lastname: Vargas
authors.forename: John T
authors.initials: JT
authors.lastname: Nguyen
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Ashitate
authors.forename: Joseph
authors.initials: J
authors.lastname: Angelo
authors.forename: Vivek
authors.initials: V
authors.lastname: Venugopal
authors.forename: Frank
authors.initials: F
authors.lastname: Kettenring
authors.forename: Florin
authors.initials: F
authors.lastname: Neacsu
authors.forename: John V
authors.initials: JV
authors.lastname: Frangioni
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gioux
authors.forename: Bernard T
authors.initials: BT
authors.lastname: Lee
mesh_terms: D000818:Animals; D010100:Oxygen / Q000032:analysis*; D010108:Oxyhemoglobins / Q000032:analysis*; D061525:Perforator Flap / Q000098:blood supply* / Q000637:transplantation; D010865:Pilot Projects; D012867:Skin / Q000098:blood supply* / Q000473:pathology; D019265:Spectroscopy, Near-Infrared; D013552:Swine
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen