Nonlinear microscopy, infrared, and Raman microspectroscopy for brain tumor analysis

摘要

Contemporary brain tumor research focuses on two challenges: First, tumor typing and grading bynanalyzing excised tissue is of utmost importance for choosing a therapy. Second, for prognostication the tumornhas to be removed as completely as possible. Nowadays, histopathology of excised tissue using haematoxylineosinenstaining is the gold standard for the definitive diagnosis of surgical pathology specimens. However, it isnneither applicable in vivo, nor does it allow for precise tumor typing in those cases when only nonrepresentativenspecimens are procured. Infrared and Raman spectroscopy allow for very precise cancer analysis due to theirnmolecular specificity, while nonlinear microscopy is a suitable tool for rapid imaging of large tissue sections. Here,nunstained samples from the brain of a domestic pig have been investigated by a multimodal nonlinear imagingnapproach combining coherent anti-Stokes Raman scattering, second harmonic generation, and two photon excitednfluorescence microscopy. Furthermore, a brain tumor specimen was additionally analyzed by linear Raman andnFourier transform infrared imaging for a detailed assessment of the tissue types that is required for classificationnand to validate the multimodal imaging approach. Hence label-free vibrational microspectroscopic imaging is anpromising tool for fast and precise in vivo diagnostics of brain tumors.