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Analysis of the Porphyrin Peak Shift and Fluorescence Lifetime in Gliomas with Different Tumor Grades, Intratumoral Regions, and Visible Fluorescence Status

  • 0Department of Neurosurgery, Medical University of Vienna, 1090 Vienna, Austria.
Diagnostics (basel, Switzerland) +

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December 17, 2024

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December 17, 2024

View abstract on PubMed

Summary

This summary is machine-generated.

5-aminolevulinic acid (5-ALA) fluorescence detects high-grade gliomas but struggles with low-grade gliomas. A new analysis reveals a spectral peak shift correlating with fluorescence lifetime, crucial for improving tumor visualization.

Area Of Science

  • Neurosurgery
  • Oncology
  • Biomedical Optics

Background

  • 5-aminolevulinic acid (5-ALA) induced Protoporphyrin IX (PpIX) fluorescence aids high-grade glioma (HGG) detection.
  • PpIX fluorescence exhibits lower sensitivity for low-grade gliomas (LGG) and HGG margins.
  • A secondary PpIX emission peak at 620 nm has been observed in LGG and HGG infiltration zones.

Purpose Of The Study

  • To investigate the significance of the 620 nm emission peak in 5-ALA-induced PpIX fluorescence.
  • To correlate the relative PpIX peak contribution (RPPC) with fluorescence lifetimes in gliomas.
  • To enhance the detection of LGG and tumor margins using fluorescence-guided surgery.

Main Methods

  • Ex vivo analysis of 43 WHO grade 2-4 gliomas after 5-ALA administration.
  • Measurement of PpIX emission spectra and fluorescence lifetimes.
  • Calculation of RPPC by integrating 615-625 nm and 625-635 nm bands.

Main Results

  • Mean RPPC decreased with lower WHO grades and in infiltrative tumor regions, indicating a shift towards the 620 nm peak.
  • Porphyrin peak shift correlated significantly with lower fluorescence lifetimes (R=0.854).
  • This spectral shift impacts fluorescence lifetime analysis by introducing contributions from other porphyrins.

Conclusions

  • The observed spectral shift of PpIX fluorescence is critical for interpreting fluorescence lifetime data.
  • Understanding this shift can optimize fluorescence-guided surgery for LGG and HGG margins.
  • This research offers a pathway to improve visualization of challenging tumor tissues.

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