A digital manual for the early diagnosis of oral neoplasia
Fluorescence spectroscopy and imaging
Fluorescence imaging is a process in which tissue is illuminated with a light source, and images of the fluorescence produced in the tissue and altered by absorption and scattering events are recorded using a camera. The presence of disease changes the concentration of the fluorophores as well as the light-scattering and absorption properties of the tissue. Use of exogenous fluorophores (protoporphyrin IX) or autofluorescence have been tried, but exogenous fluorophores has several disadvantages, such as waiting for some time after the application of the fluorophore to reach the tissues, and the residual photosensitivity following the procedure temporarly affecting the individuals daily life; low specificity is another drawback .
Autofluorescence of tissues is produced by fluorophores that naturally occur in living cells after excitation with a suitable wavelength. In autofluorescence imaging the tissue is illuminated with a light source and images of the fluorescence produced are recorded using a camera. Autofluorescence imaging is especially suitable for screening of premalignant and early malignant oral lesions .
The autofluorescence spectroscopy system consists of a light source that excites the tissue through a fibre; the fluorescence produced in the tissues is analysed by a spectrograph. The recorded spectra can be saved to a computer, which allows mathematical spectral analysis. Autofluorescence spectroscopy is useful for distinguishing lesions from healthy oral mucosa with a sensitivity above 80% and specificity above 60% . Scanning of the complete oral cavity using point spectroscopy is impossible, and autofluorescence imaging may be more appropriate and easy-to-use to detect oral lesions . Autofluorescence imaging may be useful in detecting lesions that are not easily noticed by visual inspection.