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Optimal methods for fluorescence and diffuse reflectance measurements of tissue biopsy samples
Gregory M Palmer1, Crystal L Marshek, Kristin M Vrotsos
1Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin 53706, USA.
Lasers in Surgery and Medicine
|March 14, 2002
Summary
Preserving tissue samples unfrozen ex vivo is crucial for accurate fluorescence spectroscopy. Freezing and thawing significantly alter tissue fluorescence, while unfrozen samples maintain spectral properties for up to 90 minutes post-biopsy.
Area of Science:
- Biomedical optics
- Spectroscopy
- Cancer detection
Background:
- In vivo fluorescence spectroscopy is vital for detecting pre-cancer and cancer.
- Standard protocols involve freezing biopsies, which can alter spectroscopic properties.
- Optimal tissue handling for in vitro studies requires investigation.
Purpose of the Study:
- To investigate optimal tissue handling methods for in vitro fluorescence spectroscopy.
- To compare fluorescence properties of in vivo, ex vivo, and frozen-then-thawed tissue.
- To determine the impact of tissue degradation over time on fluorescence spectra.
Main Methods:
- Epithelial tissue from Golden Syrian hamster cheek pouches was used.
- Fluorescence properties were characterized in vivo, ex vivo, and after freeze-thaw.
- Diffuse reflectance measurements evaluated oxygenation, blood volume, and scattering.
Main Results:
- Freezing and thawing significantly altered fluorescence intensity and lineshape (300-700 nm).
- Ex vivo spectra closely matched in vivo spectra, except between 500-700 nm.
- Tissue degradation over 1.5 hours caused smaller spectral changes than freeze-thaw.
Conclusions:
- Freeze-thaw effects on tissue fluorescence are more significant than degradation within 90 minutes.
- Ex vivo measurements accurately reproduce in vivo conditions for hamster cheek pouch tissue.
- Tissue samples should remain unfrozen before ex vivo fluorescence measurements.