Rapid, Label-Free Detection of Brain Tumors with Stimulated Raman Scattering Microscopy

Abstract

Surgery is an essential component in the treatment of brain tumors. However, delineating tumor from normal brain remains a major challenge. Here we describe the use of stimulated Raman scattering (SRS) microscopy for differentiating healthy human and mouse brain tissue from tumor-infiltrated brain based on histoarchitectural and biochemical differences. Unlike traditional histopathology, SRS is a label-free technique that can be rapidly performed in situ. SRS microscopy was able to differentiate tumor from non-neoplastic tissue in an infiltrative human glioblastoma xenograft mouse model based on their different Raman spectra. We further demonstrated a correlation between SRS and H&E microscopy for detection of glioma infiltration (κ=0.98). Finally, we applied SRS microscopy in vivo in mice during surgery to reveal tumor margins that were undetectable under standard operative conditions. By providing rapid intraoperative assessment of brain tissue, SRS microscopy may ultimately improve the safety and accuracy of surgeries where tumor boundaries are visually indistinct.

Quantitative comparison of 3D third harmonic generation and fluorescence microscopy images

“…The boundaries of detected bright objects (THG) and nuclei (fluorescence) are shown in green and red, respectively. helpful to figure out the best interpretation of other novel imaging modalities such as SRS microscopy [20,21], where such a quantitative comparison is currently lacking.…”

“…Like other multi-photon techniques [10][11][12][13][14][15][16][17][18], THG not only enables the recording of label-free images of unfixed 3D volumes of tissue [1][2][3][4][5][6][7][8][9][10] free from spatial distortion artifacts inherent to histopathology, but also potentially allows feedback on the nature of the tissue, i. e. whether it is healthy or tumorous, to the surgeon during surgery, as the relative speed of the imaging modalities approaches 'real' time, and no preparation steps of the tissue are required [5,6,[19][20][21][22][23]. THG was shown recently to yield label-free images of ex-vivo human tumor tissue of histopathological quality, in real-time [6].…”

“…THG images of structurally normal and tumor tissues have been compared, not one-toone, with histopathological images of the same samples stained with hematoxylin and eosin (H&E) [6]. Similarly, the interpretation of other label free imaging techniques, such as simulated Raman scattering (SRS) microscopy and optical coherence tomography (OCT), has been qualitatively linked to H&E stained images [20,21,24].…”

“…The active contour models [33][34][35][36][37][38][39][40][41][42][43] became popular for automatic cell/nuclei segmentation at the beginning of this century when the classical CV model [33] was proposed. THG images, with Raman and other nonlinear microscopy images, differ from labeled-fluorescence images in their complexity, inherent to their high information density [5,6,20,21,24,25,[44][45][46][47]62]. A limited number of segmentation methods has been explored on THG images of several tissue types.…”

Novel imaging tools for investigating the role of immune signalling in the brain

“…Raman spectroscopy and imaging has, through its ability to identify subtle changes in tissue composition, found applications in the fields of early-stage inflammatory apoptosis of adult hippocampal stem cells (Ladiwala et al 2014), cancer identification in human brain tissue (Jermyn et al 2015;Ji et al 2013) and changes in blood vessels associated with heart disease (Matthaus et al 2012). …”