Integrated Raman spectroscopy and trimodal wide-field imaging techniques for real-time in vivo tissue Raman measurements at endoscopy

Abstract

We report an integrated Raman spectroscopy and trimodal (white-light reflectance, autofluorescence, and narrow-band) imaging techniques for real-time in vivo tissue Raman measurements at endoscopy. A special 1.8 mm endoscopic Raman probe with filtering modules is developed, permitting effective elimination of interference of fluorescence background and silica Raman in fibers while maximizing tissue Raman collections. We demonstrate that high-quality in vivo Raman spectra of upper gastrointestinal tract can be acquired within 1 s or subseconds under the guidance of wide-field endoscopic imaging modalities, greatly facilitating the adoption of Raman spectroscopy into clinical research and practice during routine endoscopic inspections.

Clinical superficial Raman probe aimed for epithelial tumor detection: Phantom model results

“…During the last 20 years, several groups have constructed probes that suffice with respect to most of the criteria [7][8][9][10][11][12][13]. Nevertheless, to our knowledge, a superficial Raman probe that complies with both the MDD and the clinical/functional requirements is not yet available.…”

Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-timein vivotissue Raman measurements at endoscopy

“…[1][2][3] Very recently, NIR Raman spectroscopy techniques have gained considerable attention for characterization and diagnosis of precancer and cancer in vivo in a variety of organs such as head and neck, 2 cervix, 3 lung, 4 and gastrointestinal tracts. 5,6 To date, most NIR Raman studies have been centered on the FP range (i.e., 800 to 1800 cm ) owing to the wealth of specific biomolecular information (i.e., protein, deoxyribonucleic acid, and lipid content) contained in this spectral region for tissue characterization and diagnosis. [5][6][7] With the commonly used NIR 785 nm laser excitation source, however, intense tissue autofluorescence background and fused silica Raman signal arising from fiber-optic Raman probes also fall into the FP range.…”

“…5,6 To date, most NIR Raman studies have been centered on the FP range (i.e., 800 to 1800 cm ) owing to the wealth of specific biomolecular information (i.e., protein, deoxyribonucleic acid, and lipid content) contained in this spectral region for tissue characterization and diagnosis. [5][6][7] With the commonly used NIR 785 nm laser excitation source, however, intense tissue autofluorescence background and fused silica Raman signal arising from fiber-optic Raman probes also fall into the FP range. The tissue autofluorescence can severely interfere with the detection of the inherently weak FP Raman signals by saturating the charge-coupled device (CCD).…”

“…11 The realtime data processing specially developed for this biomedical multiplexing FP and HW Raman spectroscopy technique includes silica fiber background subtraction, intensity and wavelength calibration, cosmic rays and signal saturation detection/rejection, autofluorescence background subtraction and linear Savitzky-Golay smoothing (5 pixel window). 5 Different tissue autofluorescence background subtraction schemes were employed for robust extraction of the tissue Raman signals. In the FP region (i.e., 800 to 1800 cm −1 ), a 5th order polynomial constrained to the lower portion of the FP Raman spectra is used and this polynomial is then subtracted from the measured spectrum to resolve the FP tissue Raman signal.…”

“…All Raman spectra are also normalized to the integrated areas under the FP and HW Raman spectral regions, respectively, to reduce power density fluctuations associated with probe handling variations during clinical endoscopic examinations. 5,6 Figure 2 shows the full frame CCD image of a parabolicconfigured fiber bundle illuminated with argon/mercury spectral lamps (AR-1 and HG-1, Ocean Optics Inc., Dunedin, Florida). With this specific fiber arrangement, the atomic emission lines are substantially straight, indicating effective image-aberration correction on the segmented CCD.…”