a1 Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
a2 Department of Otolaryngology-Head and Neck Surgery, University of California Davis, Sacramento, CA 95817, USA
a3 Department of Pathology, University of California Davis, Sacramento, CA 95817, USA
a4 Department of Surgery, Hamlyn Centre, Imperial College London, London SW7 2AZ, UK
A clinically compatible fluorescence lifetime imaging microscopy (FLIM) system was developed. The system was applied to intraoperative in vivo imaging of head and neck squamous cell carcinoma (HNSCC). The endoscopic FLIM prototype integrates a gated (down to 0.2 ns) intensifier imaging system and a fiber-bundle endoscope (0.5-mm-diameter, 10,000 fibers with a gradient index lens objective 0.5 NA, 4-mm field of view), which provides intraoperative access to the surgical field. Tissue autofluorescence was induced by a pulsed laser (337 nm, 700 ps pulse width) and collected in the 460 ± 25 nm spectral band. FLIM experiments were conducted at 26 anatomic sites in ten patients during head and neck cancer surgery. HNSCC exhibited a weaker florescence intensity (~50% less) when compared with healthy tissue and a shorter average lifetime (τHNSCC = 1.21 ± 0.04 ns) than the surrounding normal tissue (τN = 1.49 ± 0.06 ns). This work demonstrates the potential of FLIM for label-free head and neck tumor demarcation during intraoperative surgical procedures.
(Received October 31 2012)
(Accepted April 09 2013)