title: Studying biological tissue with fluorescence lifetime imaging: microscopy, endoscopy, and complex decay profiles.
abstract: We have applied fluorescence lifetime imaging (FLIM) to the autofluorescence of different kinds of biological tissue in vitro, including animal tissue sections and knee joints as well as human teeth, obtaining two-dimensional maps with functional contrast. We find that fluorescence decay profiles of biological tissue are well described by the stretched exponential function (StrEF), which can represent the complex nature of tissue. The StrEF yields a continuous distribution of fluorescence lifetimes, which can be extracted with an inverse Laplace transformation, and additional information is provided by the width of the distribution. Our experimental results from FLIM microscopy in combination with the StrEF analysis indicate that this technique is ready for clinical deployment, including portability that is through the use of a compact picosecond diode laser as the excitation source. The results obtained with our FLIM endoscope successfully demonstrated the viability of this modality, though they need further optimization. We expect a custom-designed endoscope with optimized illumination and detection efficiencies to provide significantly improved performance.
authors.affiliation: Photonics Group, Department of Physics, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BW, UK.
authors.forename: Jan
authors.initials: J
authors.lastname: Siegel
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Elson
authors.forename: Stephen E D
authors.initials: SE
authors.lastname: Webb
authors.forename: K C Benny
authors.initials: KC
authors.lastname: Lee
authors.forename: Alexis
authors.initials: A
authors.lastname: Vlandas
authors.forename: Giovanni L
authors.initials: GL
authors.lastname: Gambaruto
authors.forename: Sandrine
authors.initials: S
authors.lastname: Lévêque-Fort
authors.forename: M John
authors.initials: MJ
authors.lastname: Lever
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Tadrous
authors.forename: Gordon W H
authors.initials: GW
authors.lastname: Stamp
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wallace
authors.forename: Ann
authors.initials: A
authors.lastname: Sandison
authors.forename: Tim F
authors.initials: TF
authors.lastname: Watson
authors.forename: Fernando
authors.initials: F
authors.lastname: Alvarez
authors.forename: Paul M W
authors.initials: PM
authors.lastname: French
mesh_terms: D000818:Animals; D004724:Endoscopy; D005453:Fluorescence; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology; D008856:Microscopy, Fluorescence; D055095:Optics and Photonics; D011817:Rabbits; D051381:Rats; D014070:Tooth / Q000033:anatomy & histology