Comparative study of the endoscope-based bevelled and volume fiber-optic Raman probes for optical diagnosis of gastric dysplasia in vivo at endoscopy

Abstract

This study aims to compare the diagnostic performance of the two different endoscope-based fiber-optic Raman probe designs (i.e., bevelled and volume Raman probes) for real-time, in vivo detection of gastric dysplasia at endoscopy. To conduct the clinical comparison, a total of 1,050 in vivo tissue Raman spectra (normal: n = 864; dysplasia: n = 186) were acquired from 66 gastric patients (normal: n = 48; dysplasia: n = 18) by using bevelled Raman probe, while a total of 1,913 in vivo tissue Raman spectra (normal: n = 1,786; dysplasia: n = 127) were acquired from 98 gastric patients (normal: n = 87; dysplasia: n = 11) by using volume Raman probe. The bevelled Raman probe provides approximately twofold improvements in tissue Raman-to-autofluorescence intensity ratios as compared to the use of volume Raman probe. Partial least squares discriminant analysis together with leave-one patient-out cross-validation on in vivo tissue Raman spectra acquired yields a diagnostic accuracy of 93.0 % (sensitivity of 92.5 %; specificity of 93.1 %) for differentiating gastric dysplasia from normal gastric tissue by using the bevelled fiber-optic Raman probe, which is superior to the diagnostic performance (accuracy of 88.4 %; sensitivity of 85.8 %; specificity of 88.6 %) by using the volume Raman probe. This work demonstrates that the Raman spectroscopic technique coupled with bevelled fiber-optic Raman probe has great potential to enhance in vivo diagnosis of gastric precancer and early cancer at endoscopy. Graphical Abstract Comparison of in vivo gastric tissue Raman spectra acquired by using bevelled and volume fiber-optic Raman probes.

Rapid Fiber-optic Raman Spectroscopy for Real-Time In Vivo Detection of Gastric Intestinal Metaplasia during Clinical Gastroscopy

“…Briefly, the fiber-optic Raman spectroscopic system consists of a NIR diode laser (l ex ¼ 785 nm; maximum output: 300 mW; B&W TEK Inc.), a high-throughput reflective imaging spectrograph (Acton LS-785 f/2; Princeton Instruments Inc.) equipped with a gold-coated 830 gr/mm grating and a thermo electric-cooled, NIR-optimized CCD camera (PIXIS: 400BR-eXcelon; Princeton Instruments Inc.; refs. 26,28,29 (31,32), thereby reducing the interferences and signal dilution from deeper bulky tissues, while selectively interrogating the epithelium mucosa associated with neoplastic onset and progression. At the proximal ends of the Raman probe, the excitation and emission fibers were coupled into two separate in-line filter modules: one integrated with a narrow bandpass filter for suppressing laser noise, and the other integrated with an edge longpass filter for further reduction of the scattered laser light while permitting the scattered tissue Raman signals to transmit into the Raman spectrograph.…”

“…In contrast to our previous IM Raman studies using volume-type Raman probe (47)with a poorer diagnostic sensitivity (<50%) for gastric IM, the utilization of the beveled fiberoptic Raman probe coupled with a ball-lens in this work dramatically increased the diagnostic sensitivity of gastric IM (>90%). Our Monte Carlo simulation shows that approximately 85% of the total Raman signal collected by the beveled Raman endoscopic probe is arising from the top $200 mm of the gastric mucosa (31,32), indicating that the beveled Raman probe design is more efficient for selectively targeting IM that is largely confined to the mucosal epithelium (Fig. 3B).…”

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

“…[293] Raman probes with beveled fibers collect more signals from superficial layers whereas Raman probes with nonbeveled fibers probe larger and deeper volumes.F or the real-time in vivo detection of gastric dysplasia in 66 patients using the beveled probe and in 98 patients using the nonbeveled probes, two improvements were found. [293] Raman probes with beveled fibers collect more signals from superficial layers whereas Raman probes with nonbeveled fibers probe larger and deeper volumes.F or the real-time in vivo detection of gastric dysplasia in 66 patients using the beveled probe and in 98 patients using the nonbeveled probes, two improvements were found.…”

Biomedical optical spectroscopy for the early diagnosis of gastrointestinal neoplasms

“…81,82 However, these advances heavily rely on visual information of gross morphologic changes and not on biochemical or molecular analysis, resulting in poor ability for an early diagnosis. 83 Currently, endoscopic biopsy is the standard criterion for the clinical localization and diagnosis of GICs. However, a single biopsy from the worst-appearing area is associated with sampling errors and demands for doctors with abundant clinical experiences.…”