Raman endoscopy for the in situ investigation of advancing colorectal tumors in live model mice

Abstract

The aim of the present study is to evaluate the capability of a miniaturized Raman endoscope (mRE) system to monitor the advancement of colorectal tumors in model mice as a method that is noninvasive to the tumor itself. Nevertheless, the endoscope is narrow enough to observe the inside of the mouse colon in such a way that is semi-noninvasive to the animal. However, the mRE system allowed the visualization and Raman spectral measurement of any targeted point within the colorectal tumor in model mice under anesthesia, without damaging the tissue (i.e., noninvasively). Continuous monitoring of the same tumor allowed the observation of alterations in its molecular composition and size, along with its advancement. The tumor lesion was discriminated from normal tissues of the control mouse with an accuracy of 86.8%. We succeeded in visualizing and performing Raman spectral observations on a shrinking polyp type tumor. The Raman analysis suggested that it was not cured but supposedly transformed to another tumor type.

Label‐Free Molecular Imaging of Biological Cells and Tissues by Linear and Nonlinear Raman Spectroscopic Approaches

“…[288] This system allowed the visualization and Raman spectral measurement of any targeted point within the colorectal tumor in model mice under anesthesia without damaging the tissue,that is,noninvasively.T umor lesions were discriminated from normal tissues of control mice with an accuracy of 86.8 %. [288] This system allowed the visualization and Raman spectral measurement of any targeted point within the colorectal tumor in model mice under anesthesia without damaging the tissue,that is,noninvasively.T umor lesions were discriminated from normal tissues of control mice with an accuracy of 86.8 %.…”

Systematic evaluation of the biological variance within the Raman based colorectal tissue diagnostics

“…the Raman peaks at 750 cm –1 , 783 cm –1 , 936 cm –1 and 1257 cm –1 exhibit higher intensities in the biopsy spectra as compared to both the colon and rectum spectra (see Figure B). These Raman peaks can be assigned to heme vibrations (750 cm –1 ) , different DNA/nucleic acid contributions (783 cm –1 ) as well as lipid or protein bands at 936 cm –1 and 1257 cm –1 . Furthermore, the intensity of the Raman band around 1660 cm –1 , which can be assigned to protein contributions (amide I band/C=C stretching) is decreased in the biopsy spectra .…”

“…In this context it has to be distinguished between two main tasks namely the discrimination between different diseases or subtypes or a staging of a defined tumor entity, e.g. adenocarcinoma .…”

Simultaneous Detection of EGFR and VEGF in Colorectal Cancer using Fluorescence-Raman Endoscopy

“…Fluorescence-based techniques can improve the detection ability of a routine colonoscopy with low cost and the use of a probe that lacks toxicity, but they also have limitations in that usually, only one target signal can be detected due to its broad bandwidth and autofluorescence from tissue leads to false-positive results 21–23 . In contrast, SERS-based techniques have advantages such as high sensitivity and multiplex targeting abilities, but show limitations such as a small field of view and limited study data 23–26 . In contrast, FRES can take advantage of combining a large field of view (fluorescence signal) and a multiplex ability (SERS signal) for dual-modality imaging, resulting in the rapid and accurate characterization of lesions.…”