Development of anIn Vivo Raman Spectroscopic System for Diagnostic Applications

Abstract

In recent studies, the diagnostic potential of Raman spectroscopy has been investigated. The majority of this work has been done on tissue in vitro with laboratory-based near-infrared Fourier transform (FT) Raman systems. In vivo Raman spectroscopy is hindered by tissue fluorescence, which is several orders of magnitude greater than the Raman signal, and by the spectral contribution of the delivery and collection fiber optics. An in vivo Raman system (IVRS) is described which can obtain spectra in vivo from tissue in less than 30 s. The system is compact and mobile, making it suitable for clinical applications. Major system components, such as the spectrograph, CCD detector, laser diode and fiber-optic probes, are described in detail. The methods of wavenumber calibration, intensity correction and baseline subtraction are outlined. Spectra which were collected in vivo from human skin, buccal cheek epithelium, fingernail and a tooth are presented and major peaks are assigned. The performance of the IVRS was compared with that of an FT-Raman system. With similar collection parameters, the IVRS spectra had superior signal-to-noise ratios owing to the shorter excitation wavelength (785 nm versus 1064 nm) and the high transmission (>50%) of the IVRS spectrograph. Planned system upgrades are discussed together with the anticipated improvements in system performance. © 1997 by John Wiley & Sons, Ltd.