Researcher:
Brian Wilson, Professor of Medical Physics, University of Toronto
Project:
Identifying and quantifying brain-tumor tissue to allow surgeons who are resecting a tumor to determine if any cancerous cells remain
Problem:
Wilson encountered a trifecta of confounding factors that often plague in vivo fluorescence: Background autofluorescence masks the signal; optical absorption and scattering can reduce both excitation and emission intensity; and changes in position, angle, and distance of the light source and camera all influence the measured intensity.
Solution:
Wilson developed a protocol that compensates for all three problems at once. He harnesses an endogenous fluorophore, protoporphyrin-IX (PpIX), to act as his fluorescent marker. PpIX has a very low native presence in the brain, so he first washes the region of interest with 5-aminolevulinic acid (ALA); the ALA triggers an increase in the cancer cells' metabolism, which then boosts their levels of PpIX. The tissues thus express their own ...
