ABSTRACT
This chapter focuses on endogenous fluorescence lifetime imaging (FLI) in biomedicine, with discussions on technology and examples of applications. It introduces fundamental concepts in fluorescence lifetime spectroscopy and describes several useful biological and biomedical imaging implementations of the method. The chapter explains both time- and frequency-domain approaches to fluorescence lifetime measurement, with an emphasis on strategies employed for microscopic imaging, including several approaches to imaging in turbid biological media via optical sectioning. Multiphoton microscopy is a method with inherent spatial sectioning. The chapter highlights several applications of endogenous fluorescence lifetime imaging, ranging from cellular biological studies to in vivo tissue and clinical endoscopic studies. Cellular studies have focused on using endogenous fluorescence lifetimes for monitoring metabolism. Tissue studies involved developing methods for deep imaging, analyzing complex fluorescence decays, and modeling fluorescence lifetimes in diffusive media. FLI and FLI microscopy are methods for producing spatially resolved images of fluorescence lifetimes.
