Fluorescence lifetime contrast in small animal imaging

V. Krishnan Ramanujan, Abhik Bandyopadhyay, Lu Zhe Sun, Brian A. Herman

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Early detection of primary tumors is the key for effective therapeutic intervention and successful patient survival. Small animal models emulating human diseases are powerful tools for our comprehensive understanding of the pathophysiology of tumor formation and metastasis to distant sites. Our long-term goal is to develop a non-invasive, multiphoton-fluorescence lifetime imaging (MP-FLIM) modality that can precisely quantify these steps in animal tumor models at a very early stage. The specific hypothesis is that fluorescence lifetime can be employed as reliable contrast parameter for providing higher detection sensitivity as compared with conventional intensity-based tumor imaging approaches and therefore it is possible to detect smaller tumor volumes (early detection) than those achieved by other prevailing methods. We base this hypothesis on our recent observations that (1) fluorescence lifetime is "intrinsic" to the fluorophore and its measurement is not affected by concentration and/or spectral artifacts as in intensity-based methods, (2) multiphoton excitation can enable increased tissue penetrability and reduced phototoxicity and (3) MP-FLIM approach can discriminate background autofluorescence from the fluorescent proteins in thick tissues thereby achieving a ten-fold increase in signal-to-background ratio over the intensity-based approaches. We present our preliminary data to support this hypothesis in primary tumor detection in nu/nu athymic mouse models.

Original languageEnglish (US)
Title of host publicationGenetically Engineered and Optical Probes for Biomedical Applications IV
StatePublished - 2007
EventGenetically Engineered and Optical Probes for Biomedical Applications IV - San Jose, CA, United States
Duration: Jan 23 2007Jan 24 2007

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


OtherGenetically Engineered and Optical Probes for Biomedical Applications IV
Country/TerritoryUnited States
CitySan Jose, CA


  • Lifetime imaging
  • Multiphoton imaging
  • Small animal models
  • Tumor imaging

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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