Article
Fluorescence-based measurement of real-time kinetics of Protoporphyrin IX after 5-Aminolevulinic acid administration in human in situ malignant gliomas
Fluoreszenzbasierte Messung der Echtzeitkinetik von Protoporphyrin IX nach Verabreichung von 5-Aminolävulinsäure in malignen humanen Gliomen
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Published: | May 8, 2019 |
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Objective: It is well established that use of Five-aminolevulinic acid (5-ALA) what elicites the accumulation of protoporphyrin IX (PpIX) for fluorescence-guided resections of malignant gliomas. Although 5-ALA is recommended to be administered 3 hours before surgery, the time-dependency of tumor fluorescence has not yet been evaluated in humans. We aimed to investigate the time-dependency of PpIX by measuring fluorescence intensities in tumors at various time points during surgery.
Methods: Patients took 5-ALA (20 mg/kg b.w.) 3–4 hours before surgery. Fluorescence intensities and estimated tumor PpIX concentrations were measured in the tumor tissues with a hyperspectral camera. PPIX concentrations was calculated with using hyperspectral imaging and fluorescence phantoms with known PPIX concentrations.
Results: 201 samples from 68 patients were evaluated in this study. On average, maximum values of calculated Fluorescence intensities and PPIX concentrations were observed between 7 and 8 hours after 5-ALA administration. Both Fluorescence intensities and PPIX concentrations distinguished strong and weak fluorescence. Moreover, grade IV gliomas had higher average of value than grade III gliomas.
Conclusion: In malignant glioma tissue, we found that fluorescence after 5-ALA administration peaked later than previously thought. In consequence, 5-ALA should be administered 4-5 hours before surgery.