Text

theses

In vivo fluorescence imaging is an emerging technique with potential for usage in non-invasive cancer screening, surveillance, real-time surgical guidance, and staging. Fluorescence imaging uses the interaction of non-ionizing optical radiation with endogenous fluorophores or fluorescent labels to provide real-time wide-field images of tissue structure and/or functional components. When imaging in vivo, excitation light must travel through overlying tissue to reach the fluorescent target and emitted fluorescence must then propagate back through the overlying tissue in order to be imaged onto a camera. Recently, fluorescent contrast agents have been developed with excitation and emission wavelengths in the near infrared (NIR) spectrum (~700 – 1,000 nm) in order to minimize attenuation and maximize the measured signal from tissue. While several clinical trials have shown the potential benefits of NIR contrast agents over visible fluorophores, there may still be room for improvement by moving to even longer wavelengths. As scattering is reduced as wavelength increases, some researchers are investigating fluorophores that emit in the short-wave infrared (SWIR) wavelength region (~1,000 – 2,300 nm). This study focuses on examining optical transmission and image contrast at NIR wavelengths and SWIR wavelengths to determine which wavelength region may be optimal for development of fluorescent contrast agents. Transmission and contrast measurements were performed on both tissue simulating phantoms and real biological tissues using 780 nm, 980 nm, and 1550 nm wavelengths. From the experiments conducted, it appears that fluorophore emissions should be chosen based on the goals of the specific application. For an application that requires simple detection of signal, near infrared wavelengths will be better as they can be detected with higher signal levels. For an application that focuses on imaging fluorophore-labeled tissues, short-wave infrared wavelengths will be the better option as they provided better image contrast

ETD_8484

M.S.

Includes bibliographical references

by Khushbu Dipak Patel

doi:10.7282/T38S4T2V

ETD graduate

The author owns the copyright to this work.