Fluorescence Lifetime Spectroscopy and Imaging Technology

Clinical applications of autofluorescence diagnostic techniques have been in majority based on steady-state fluorescence technique as such approach makes use of relative simple and rather inexpensive instrumental setups.

FLIM_translational

However, this technique relies on measurements of fluorescence emission intensity and/or spectrum which are affected by numerous experimental factors including irregular tissue surfaces, sample non-uniform illumination, and the presence of endogenous absorbers such as blood in the operative field. An alternative method that addresses such limitations is based on time-resolved (lifetime) measurement of fluorescence emission.
This technique can resolve the exited state lifetimes and improve the specificity of fluorescence measurements. Despite recognized advantages, however, the full potential value of time-resolved fluorescence spectroscopy or imaging techniques has been only sparsely evaluated in clinical settings. Barriers to clinical translation include the complexity of the instrumental setups, the lengthy data acquisition and analysis, and the high instrumentation cost associated with these techniques. Research in our laboratory is focused on addressing such challenges.

We research both time-resolved fluorescence spectroscopy (TRFS) as well as fluorescence lifetime imaging microscopy (FLIM) techniques that enables practical applications of these technologies. A novel approach to fluorescence lifetime instrumentation was developed more recently in our laboratory. This enables multispectral time-resolved fluorescence spectroscopy (ms-TRFS) of tissues and development of versatile diagnostics systems that can operate as both point-spectroscopy and scanning imaging spectroscopy devices.

Endoscopic wide-field FLIM system

FLIM

Fast multi-spectral Fluorescence Lifetime Imaging (ms-FLIm)

Fast Multi-spectral FLIm scanning setup. Bavnd-pass filters and dichroic mirros along with optical delay fibers of varying lengths allows simultaneous acquisition of fluorescence signals from different wavelength sub-bands.

Fast multi-spectral FLIm scanning setup. Band-pass filters and dichroic mirrors along with optical delay fibers of varying lengths allows simultaneous acquisition of fluorescence signals from different wavelength sub-bands.

Related Publications

L. Marcu, “Fluorescence Lifetime Techniques in Medical Applications,” Annals of Biomedical Engineering 40(2), 304-331 (2012). (Link)

Y.H. Sun, N. Hatami, M. Yee, D.S. Elson, F. Gorin, R.J. Schrot, L. Marcu. “Fluorescence lifetime imaging microscopy for brain tumor image-guided surgery.” J Biomed Opt. 2010 Sep-Oct; 15(5): 056022. (Link)

D. Yankelevich, D. Ma, J. Liu, Y. Sun, Y. Sun, J. Bec, D. S. Elson, L. Marcu, “Design and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging”  Review of Scientific Instruments, 85, 034303 (2014) (Link)

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