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

Abstract

Colorectal cancer (CRC) is the third most common type of cancer worldwide and the second most deadly. Recent research efforts have focused on developing non-invasive techniques for CRC detection. In this study, we evaluated the diagnostic capabilities of diffuse reflectance spectroscopy (DRS) for CRC detection by building 6 classification models based on support vector machines (SVMs). Our dataset consists of 2889 diffuse reflectance spectra collected from freshly excised ex vivo tissues of 47 patients over wavelengths ranging from 350 and 1919 nm with source-detector distances of 630-µm and 2500-µm to probe different depths. Quadratic SVMs were used and performance was evaluated using twofold cross-validation on 10 iterations of randomized training and test sets. We achieved (93.5 ± 2.4)% sensitivity, (94.0 ± 1.7)% specificity AUC by probing the superficial colorectal tissue and (96.1 ± 1.8)% sensitivity, (95.7 ± 0.6)% specificity AUC by sampling deeper tissue layers. To the best of our knowledge, this is the first DRS study to investigate the potential of probing deeper tissue layers using larger SDD probes for CRC detection in the luminal wall. The data analysis showed that using a broader spectrum and longer near-infrared wavelengths can improve the diagnostic accuracy of CRC as well as probing deeper tissue layers.

Real-time tracking of a diffuse reflectance spectroscopy probe used to aid histological validation of margin assessment in upper gastrointestinal cancer resection surgery

“…Diffuse reflectance spectroscopy (DRS) is a technique that allows discrimination of normal and abnormal tissue based on spectral data and presents a promising advancement in cancer diagnosis. 11 – 14 When compared to sophisticated micro-endoscopic probes, DRS has lower costs and is simpler because it does not require lasers or magnification optics. The main limitation of the clinical use of DRS is that, although DRS can discriminate tissue types, it does so by providing single-point spectral measurements and leaves no marks on the tissue during scanning.…”

Layer thickness prediction and tissue classification in two-layered tissue structures using diffuse reflectance spectroscopy

“…The detected diffuse reflectance spectrum of this light represents an “optical fingerprint” of the measured tissue, which can be analyzed. DRS has been successfully evaluated for detection of cancer in breast 20 , 21 , 29 , colorectal 30 – 34 , head and neck 22 , 35 , 36 , liver 23 , 24 , lung 25 , 26 , and brain 27 , 28 tissue, in both ex vivo and in vivo studies. These studies showed that tumor tissue could be discriminated from healthy tissue with classification accuracies of 0.77–1.00, suggesting this technique has a great potential for real-time tissue assessment during surgery.…”

Picosecond-resolved fluorescence resonance energy transfer (FRET) in diffuse reflectance spectroscopy explores biologically relevant hidden molecular contacts in a non-invasive way

“…The strategy involving non-destructive spectroscopic measurement often uses diffuse reflectance spectroscopy (DRS), a subset of absorption spectroscopy, which relies on the reflection or back-scattering of light by a material, while transmission is the passage of light through a material. 13,14 In the past decade, DRS has made significant contributions to the identification of biological tissues through analysis of the biochemical compositions, oxygenation level and also micro-environment of the tissue layers. 13,15 The DRS technique is based on the amount of light collected from the tissue layers after penetration of the incident light.…”