Synergy of Fluorescence and Near-Infrared Spectroscopy in Detection of Colorectal Cancer

Abstract

Magnetic resonance spectroscopy a b s t r a c tBackground: Colorectal cancer is one of the most common malignancies worldwide. There is an urgent need for simple and fast methods to improve tumor detection in the diagnostic and intraoperative setting to avoid complications and provide objective information in distinguishing malignant and benign colorectal tissue. Optical spectroscopy methods have recently shown a great potential for this discrimination in different organs. Materials and methods:In this pilot study, fluorescence emission spectra (excitation: 473 nm) and diffuse reflectance spectra (DRS) of normal and tumor tissues from resected colorectal cancer specimen were measured using fiber optical probes in an ex vivo setting, and the data were subjected to multivariate analysis.Results: Substantial spectral differences were found in the fluorescence and DRS spectra of colorectal cancer tissue in comparison to benign tissue. The diagnostic potential of a multimode optical system combining both spectroscopic methods was investigated by mathematical combination. Compared with the individual techniques, a higher sensitivity of the joint DRS-fluorescence optical system in the discrimination between malignant and benign colorectal tissue could be observed. Conclusions:In the pilot study presented herein, a quick and reliable method to differentiate malignant and benign colorectal tissue ex vivo with different spectroscopic techniques using spectral fiber probes could be established. Joint fluorescence and near-infrared spectroscopy had a higher sensitivity in tissue discrimination and showed to be a promising combination of two spectroscopic methods. Further studies using the synergic effect of fluorescence and DRS spectroscopy are needed to transfer these findings into the in vivo situation. ª

Evaluation of wavelength ranges and tissue depth probed by diffuse reflectance spectroscopy for colorectal cancer detection

“…As expected, the closest classification performance compared to the present study was the SVM classifier. Still, Ehlen et al 48 found 6.1% higher sensitivity, 20% lower specificity and 5.4% lower accuracy compared to the present study, which may be originated by using 400-µm fiber SDD and substantially smaller sample size (number of patients and spectra).…”

“…Usefulness of the extended wavelength range. Based on the classification performance on the wavelength ranges of previous studies [39][40][41][42][43][44][45][46][47][48][49][50] , we analyzed the potential benefit of using the extended wavelength for colorectal cancer (CRC) detection. In order to be consistent with the findings of previous studies, this analysis consisted of the comparison of the sensitivity, specificity, accuracy and AUC using the small SDD probe (Table 4).…”

“…From a clinical perspective, biomolecular changes probed by optical techniques can potentially obviate the need for multiple biopsies or polypectomies of normal mucosa as well as identify sessile serrated polyps, which may be difficult to recognize during colonoscopy at times [7][8][9][10][11][12][13][14][15][16][17][18][19][20] . The potential of optical spectroscopy for colorectal cancer (CRC) detection in ex vivo specimens or in vivo during colonoscopy has been evaluated for superficial tissues (small SDD probes) in several wavelength ranges [39][40][41][42][43][44][45][46][47][48][49][50] . To the best of our knowledge, this is the first study that uses DRS information from deeper tissue layers (2500 µm SDD) to detect cancerous tissues in the luminal wall of ex vivo specimens for colonoscopy applications.…”

“…6). Prior DRS and HSI studies focused on analysis using visible light, except by Chen et al [45][46][47] , Ehlen et al 48 and Yuan et al 42 . The typically targeted near-infrared wavelength region contains information about the water and lipid absorption.…”

“…Comparison with previous studies. The classification performance for colorectal cancer detection achieved in this study was compared to similar studies investigating DRS, elastic scattering, near-infrared spectroscopy (reflectance modality) and hyperspectral imaging [39][40][41][42][43][44][45][46][47][48][49][50] . This comparison involved listing the type of tissue evaluation (in vivo or ex vivo), number of patients, wavelength range, source-to-detector distance, types of tissue analyzed, number of analyzed spectra, tissue types used for classification, and diagnostic performance metrics (sensitivity, specificity, accuracy, and AUC).…”