title: A ratiometric threshold for determining presence of cancer during fluorescence-guided surgery.
abstract: OBJECTIVE
  Fluorescence-guided imaging to assist in identification of malignant margins has the potential to dramatically improve oncologic surgery. However, a standardized method for quantitative assessment of disease-specific fluorescence has not been investigated. Introduced here is a ratiometric threshold derived from mean fluorescent tissue intensity that can be used to semi-quantitatively delineate tumor from normal tissue.
  
  
  METHODS
  Open-field and a closed-field imaging devices were used to quantify fluorescence in punch biopsy tissues sampled from primary tumors collected during a phase 1 trial evaluating the safety of cetuximab-IRDye800 in patients (n = 11) undergoing surgical intervention for head and neck cancer. Fluorescence ratios were calculated using mean fluorescence intensity (MFI) from punch biopsy normalized by MFI of patient-matched tissues. Ratios were compared to pathological assessment and a ratiometric threshold was established to predict presence of cancer.
  
  
  RESULTS
  During open-field imaging using an intraoperative device, the threshold for muscle normalized tumor fluorescence was found to be 2.7, which produced a sensitivity of 90.5% and specificity of 78.6% for delineating disease tissue. The skin-normalized threshold generated greater sensitivity (92.9%) and specificity (81.0%).
  
  
  CONCLUSIONS
  Successful implementation of a semi-quantitative threshold can provide a scientific methodology for delineating disease from normal tissue during fluorescence-guided resection of cancer.
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Warram
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Esther
authors.initials: E
authors.lastname: de Boer
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Lindsay S
authors.initials: LS
authors.lastname: Moore
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Cecelia E
authors.initials: CE
authors.lastname: Schmalbach
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Kirk P
authors.initials: KP
authors.lastname: Withrow
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: William R
authors.initials: WR
authors.lastname: Carroll
authors.affiliation: Division of General Surgery, Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Richman
authors.affiliation: Department of Oral & Maxillofacial Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Anthony B
authors.initials: AB
authors.lastname: Morlandt
authors.affiliation: Division of Anatomic Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Margaret
authors.initials: M
authors.lastname: Brandwein-Gensler
authors.affiliation: Division of Otolaryngology, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Eben L
authors.initials: EL
authors.lastname: Rosenthal
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000601:surgery*; D005453:Fluorescence; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D009367:Neoplasm Staging; D011379:Prognosis; D012372:ROC Curve; D025321:Surgery, Computer-Assisted
keywords: fluorescence-guided surgery; head & neck cancer; standardized imaging; surgical oncology