Aminolevulinc-acid induced protoporphyrin IX (ALA-PpIX) is being investigated as a biomarker to guide neurosurgical resection of brain tumors. ALA-PpIX fluorescence can be observed visually in the surgical field; however, raw fluorescence emissions can be distorted by factors other than the fluorophore concentration. Specifically, fluorescence emissions are mixed with autofluorescence and attenuated by background absorption and scattering properties of the tissue. Recent work at Dartmouth has developed advanced fluorescence detection approaches that return quantitative assessments of PpIX concentration, which are independent of background optical properties. The quantitative fluorescence imaging (qFI) approach has increased sensitivity to residual disease within the resection cavity at the end of surgery that was not visible to the naked eye through the operating microscope.
This presentation outlines clinical observations made during an ongoing investigation of ALA-PpIX based guidance of tumor resection. PpIX fluorescence measurements made in a wide-field hyperspectral imaging approach are co-registered with point-assessment using a fiber optic probe. Data show variations in the measured PpIX accumulation among different clinical tumor grades (i.e. high grade glioma, low grade glioma), types (i.e. primary tumors. metastases) and normal structures of interest (e.g. normal cortex, hippocampus). These results highlight the contrast enhancement and underscore the potential clinical benefit offered from quantitative measurements of PpIX concentration during resection of intracranial tumors.
Jonathan D. Olson, Stephen C. Kanick, Jaime J. Bravo, David W. Roberts, and Keith D. Paulsen, "Ongoing advances in quantitative PpIX fluorescence guided intracranial tumor resection
(Conference Presentation)," Proc. SPIE 9696, Molecular-Guided Surgery: Molecules, Devices, and Applications II, 969612 (Presented at SPIE BiOS: February 14, 2016; Published: 26 April 2016); https://doi.org/10.1117/12.2213181.4848635748001.
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