RAMAN SPECTROSCOPY FOR IN VIVO TISSUE ANALYSIS AND DIAGNOSIS, FROM INSTRUMENT DEVELOPMENT TO CLINICAL APPLICATIONS

Abstract

Raman spectroscopy is a noninvasive, nondestructive analytical method capable of determining the biochemical constituents based on molecular vibrations. It does not require sample preparation or pretreatment. However, the use of Raman spectroscopy for in vivo clinical applications will depend on the feasibility of measuring Raman spectra in a relatively short time period (a few seconds). In this work, a fast dispersive-type near-infrared (NIR) Raman spectroscopy system and a skin Raman probe were developed to facilitate real-time, noninvasive, in vivo human skin measurements. Spectrograph image aberration was corrected by a parabolic-line fiber array, permitting complete CCD vertical binning, thereby yielding a 16-fold improvement in signal-to-noise ratio. Good quality in vivo skin NIR Raman spectra free of interference from fiber fluorescence and silica Raman scattering can be acquired within one second, which greatly facilitates practical noninvasive tissue characterization and clinical diagnosis. Currently, we are conducting a large clinical study of various skin diseases in order to develop Raman spectroscopy into a useful tool for non-invasive skin cancer detection. Intermediate data analysis results are presented. Recently, we have also successfully developed a technically more challenging endoscopic Laser-Raman probe for early lung cancer detection. Preliminary in vivo results from endoscopic lung Raman measurements are discussed.