Date of Award
Master of Applied Science (MASc)
Current gold standard practices for the diagnosis of tissue disease involve invasive tissue biopsies subjected to a time consuming histopathological examination process. An optical biopsy can offer a non-invasive diagnostic alternative by exploiting the properties of naturally occurring light-tissue interactions. A time-resolved fluorescence spectroscopy instrument (355 nm excitation) has previously been developed by our lab to capture the fluorescence response of gastrointestinal tissue (370-550 nm in 5 nm increments, 25 ns at 1000 ps/pt). Measurements were conducted ex-vivo during routine upper gastrointestinal tract biopsies on duodenum, antrum, stomach body, and esophageal tissue. The work currently presented is focused on protocol development for tissue handling, measurement collection, clinical data management, fluorescent decay modeling using Laguerre based deconvolution, instrument performance evaluation, and k-means based classification.
Descriptive parameters derived from spectral (total signal intensity) and temporal (lifetime and Laguerre polynomial coefficients) analysis were used to evaluate the data. It was found that data were only compromised when the total signal intensity for the peak wavelength 455 nm fell blow 19.5 V·ns. The data did not exhibit any signs of photobleaching or pulse width broadening that would have otherwise distorted the lifetime from its true fluorescence response. Data for diseased tissue were limited so the clinical diagnosis was used to classify normal duodenum tissue from normal esophageal tissue. Over 400 pairs of parameters demonstrated k-means can identify duodenum tissue with 87.5 % sensitivity and 87.5 % specificity or better. With some dimensional axis transformations these results could be improved. The lifetimes are not factors here but the relative intensity and decay shape were. Protocols can be applied to diseased or other tissue types with little adaptation. Just a single set of parameters may hold the key to help surgeons choose optimum locations for traditional biopsies or perhaps one day replace them altogether.
LePalud, Michelle L., "DEVELOPMENT AND APPLICATION OF TIME-RESOLVED FLUORESCENCE SPECTROSCOPY ANALYSIS WITH SPECIMENS OF THE UPPER GI TRACT" (2012). Open Access Dissertations and Theses. Paper 6976.
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