Studying biological tissue with fluorescence lifetime imaging: microscopy, endoscopy, and complex decay profiles.
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.
Siegel
Jan
J
Photonics Group, Department of Physics, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BW, UK.
Elson
Daniel S
DS
Webb
Stephen E D
SE
Lee
K C Benny
KC
Vlandas
Alexis
A
Gambaruto
Giovanni L
GL
Lévêque-Fort
Sandrine
S
Lever
M John
MJ
Tadrous
Paul J
PJ
Stamp
Gordon W H
GW
Wallace
Andrew L
AL
Sandison
Ann
A
Watson
Tim F
TF
Alvarez
Fernando
F
French
Paul M W
PM
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