title: Time-resolved laser-induced fluorescence spectroscopy as a diagnostic instrument in head and neck carcinoma.
abstract: OBJECTIVE
  The objectives of this study were to 1) determine differences in lifetime fluorescence between normal and malignant tissue of the upper aerodigestive tract, and 2) evaluate the potential of time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) as a diagnostic instrument for head and neck squamous cell carcinoma (HNSCC).
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  University-based medical center.
  
  
  METHODS
  Nine patients with suspected HNSCC were included. In the operating room, a nitrogen pulse laser (337 nm, 700-picosecond pulse width) was used to induce tissue autofluorescence of normal tissue and suspected malignant lesions. Spectral intensities and time-domain measurements were obtained and compared with the histopathology at each site. A total of 53 sites were measured. The fluorescence parameters that provided the most discrimination were determined.
  
  
  RESULTS
  Differences in spectral intensities allowed for discrimination between malignant and normal tissue. The spectral intensity of malignant tissue was lower than that of normal tissue, and a shift of peak intensity to a longer wavelength was observed in the normalized spectrum of malignant tissue in the range of 360 to approximately 660 nm. Multiple time-resolved fluorescence parameters provided the best diagnostic discrimination between normal tissue and carcinoma, including average lifetimes (i.e., at 390 nm: 1.7 +/- 0.06 ns [not significant] for normal and 1.3 +/- 0.06 ns for tumor, P = 0.0025) and the second-order Laguerre expansion coefficient (LEC-2) (i.e., at 460 nm: 0.135 +/- 0.001 for normal and 0.155 +/- 0.007 for tumor, P < 0.05).
  
  
  CONCLUSIONS
  These findings highlight some of the differences in lifetime fluorescence between normal and malignant tissue. TR-LIFS has potential as a noninvasive diagnostic technique for HNSCC.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of California Davis, Sacramento, CA 95817, USA. jeremy.meier@ucdmc.ucdavis.edu
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Meier
authors.forename: Hongtao
authors.initials: H
authors.lastname: Xie
authors.forename: Yang
authors.initials: Y
authors.lastname: Sun
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Sun
authors.forename: Nisa
authors.initials: N
authors.lastname: Hatami
authors.forename: Brian
authors.initials: B
authors.lastname: Poirier
authors.forename: Laura
authors.initials: L
authors.lastname: Marcu
authors.forename: D Gregory
authors.initials: DG
authors.lastname: Farwell
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D006258:Head and Neck Neoplasms / Q000175:diagnosis*; D006801:Humans; D007834:Lasers; D013050:Spectrometry, Fluorescence / Q000379:methods*