Flavin fluorescence lifetime and autofluorescence optical redox ratio for improved visualization and classification of brain tumors

David Reichert; Lisa I Wadiura; Mikael T Erkkilae; Johanna Gesperger; Alexandra Lang; Thomas Roetzer-Pejrimovsky; Jessica Makolli; Adelheid Woehrer; Marco Wilzbach; Christoph Hauger; Barbara Kiesel; Marco Andreana; Angelika Unterhuber; Wolfgang Drexler; Georg Widhalm; Rainer A Leitgeb

doi:10.3389/fonc.2023.1105648

Flavin fluorescence lifetime and autofluorescence optical redox ratio for improved visualization and classification of brain tumors

Front Oncol. 2023 Feb 20:13:1105648. doi: 10.3389/fonc.2023.1105648. eCollection 2023.

Authors

David Reichert^{1

2}, Lisa I Wadiura³, Mikael T Erkkilae¹, Johanna Gesperger^{1

4}, Alexandra Lang³, Thomas Roetzer-Pejrimovsky⁴, Jessica Makolli³, Adelheid Woehrer⁴, Marco Wilzbach⁵, Christoph Hauger⁵, Barbara Kiesel³, Marco Andreana¹, Angelika Unterhuber¹, Wolfgang Drexler¹, Georg Widhalm³, Rainer A Leitgeb^{1

2}

Affiliations

¹ Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
² Christian Doppler Laboratory for Innovative Optical Imaging and its Translation to Medicine (OPTRAMED), Medical University of Vienna, Vienna, Austria.
³ Department of Neurosurgery, General Hospital and Medical University of Vienna, Vienna, Austria.
⁴ Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Vienna, Austria.
⁵ Advanced Development Microsurgery, Carl Zeiss Meditec AG, Oberkochen, Germany.

Abstract

Purpose: Modern techniques for improved tumor visualization have the aim to maximize the extent of resection during brain tumor surgery and thus improve patient prognosis. Optical imaging of autofluorescence is a powerful and non-invasive tool to monitor metabolic changes and transformation in brain tumors. Cellular redox ratios can be retrieved from fluorescence emitted by the coenzymes reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) and flavin adenine dinucleotide (FAD). Recent studies point out that the influence of flavin mononucleotide (FMN) has been underestimated.

Experimental design: Fluorescence lifetime imaging and fluorescence spectroscopy were performed through a modified surgical microscope. We acquired 361 flavin fluorescence lifetime (500-580 nm) and fluorescence spectra (430-740 nm) data points on freshly excised different brain tumors: low-grade gliomas (N=17), high-grade gliomas (N=42), meningiomas (N=23), metastases (N=26) and specimens from the non-tumorous brain (N=3).

Results: Protein-bound FMN fluorescence in brain tumors did increase with a shift toward a more glycolytic metabolism (R=-0.87). This increased the average flavin fluorescence lifetime in tumor entities with respect to the non-tumorous brain. Further, these metrics were characteristic for the different tumor entities and showed promise for machine learning based brain tumor classification.

Conclusions: Our results shed light on FMN fluorescence in metabolic imaging and outline the potential for supporting the neurosurgeon in visualizing and classifying brain tumor tissue during surgery.

Keywords: flavin mononucleotide; fluorescence guided surgery; fluorescence lifetime imaging; fluorescence spectroscopy; optical redox ratio.

Grants and funding

This project has received funding from the Austrian Christian Doppler Research Association as well as from the innovation board of the Carl Zeiss Meditec AG (DR, RL) who were not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication. TR-P is recipient of a DOC Fellowship of the Austrian Academy of Sciences at the Division of Neuropathology and Neurochemistry (25262). JG is supported by OeNB grant 16725 to AW. The financial support by the Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development is gratefully acknowledged. This project has furthermore received funding from the European Union Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement (MSCA grant 721766, ME, RL, WD) and the Bürgermeister grant ‘Quantitative measurement of 5-ALA fluorescence for improved detection of low-grade gliomas’ (Projektnummer: 19104).