Real-time depth-resolved fiber optic Raman endoscopy for in vivo diagnosis of gastric precancer

Raman spectroscopy represents a unique optical vibrational technique based on the fundamental premise of inelastic light scattering. Raman spectroscopy enables histopathological assessment at the biomolecular level. We have developed a fiber-optic depth-resolved near-infrared (NIR)Raman endoscopy technique integrated with on-line diagnostic algorithms for in vivo real-time epithelial diagnostics under multimodal wide-field imaging (i. e., white light reflectance (WLR), narrow-band imaging (NBI), autofluorescence imaging (AFI)) modalities. A selection of 450 patients who previously underwent Raman endoscopy (n= 1900 spectra) was used to render diagnostic models for identifying gastric precancer (i. e., dysplasia) based on probabilistic partial least squares (PLS) discriminant analysis (DA). The on- line Raman endoscopy technique was tested prospectively on (n= 5) patients for real-time in vivo gastric epithelium tissue diagnosis. The fiber-optic confocal Raman endoscopic technique developed could prospectively identify gastric dysplasia in real-time with a sensitivity: 81.3% (61/ 75) and specificity 88.3% (188/ 213) on spectrum basis. On lesion basis, all dysplastic lesions were identified. This study successfully demonstrates for the first time the prospective real-time in vivo diagnosis of gastric precancer using depth-resolved Raman endoscopy.