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Maximizing the extent of brain tumor resection correlates with improved survival and quality of life outcomes in
patients. Optimal surgical resection requires accurate discrimination between normal and abnormal, cancerous tissue. We
present our recent experience using quantitative optical spectroscopy in 5-aminolevulinic acid (ALA)-induced
protoporphyrin IX (PpIX) fluorescence-guided resection. Exogenous administration of ALA leads to preferential
accumulation in tumor tissue of the fluorescent compound, PpIX, which can be used for in vivo surgical guidance. Using
the state of the art approach with a fluorescence surgical microscope, we have been able to visualize a subset of brain
tumors, but the sensitivity and accuracy of fluorescence detection for tumor tissue with this system are low. To take full
advantage of the biological selectivity of PpIX accumulation in brain tumors, we used a quantitative optical spectroscopy
system for in vivo measurements of PpIX tissue concentrations. We have shown that, using our quantitative approach for
determination of biomarker concentrations, ALA-induced PpIX fluorescence-guidance can achieve accuracies of greater
than 90% for most tumor histologies. Here we show multivariate analysis of fluorescence and diffuse reflectance signals
in brain tumors with comparable diagnostic performance to our previously reported quantitative approach. These results
are promising, since they show that technological improvements in current fluorescence-guided surgical technologies
and more biologically relevant approaches are required to take full advantage of fluorescent biomarkers, achieve better
tumor identification, increase extent of resection, and subsequently, lead to improve survival and quality of life in
patients.
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