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Proceedings Paper

Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy
Author(s): Niklas Markwardt; Marcus Götz; Neda Haj-Hosseini; Bastian Hollnburger; Ronald Sroka; Herbert Stepp; Petr Zelenkov; Adrian Rühm
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Paper Abstract

5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that – without blood layer – the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle’s coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

Paper Details

Date Published: 27 April 2016
PDF: 12 pages
Proc. SPIE 9887, Biophotonics: Photonic Solutions for Better Health Care V, 98872Z (27 April 2016); doi: 10.1117/12.2225234
Show Author Affiliations
Niklas Markwardt, Klinikum der Univ. München (Germany)
Marcus Götz, MRC Systems GmbH (Germany)
Neda Haj-Hosseini, Linköping Univ. (Sweden)
Bastian Hollnburger, Klinikum der Univ. München (Germany)
Ronald Sroka, Klinikum der Univ. München (Germany)
Herbert Stepp, Klinikum der Univ. München (Germany)
Petr Zelenkov, N.N. Burdenko Neurosurgical Institute (Russian Federation)
Adrian Rühm, Klinikum der Univ. München (Germany)

Published in SPIE Proceedings Vol. 9887:
Biophotonics: Photonic Solutions for Better Health Care V
Jürgen Popp; Valery V. Tuchin; Dennis L. Matthews; Francesco Saverio Pavone, Editor(s)

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