Study of fiber-optic probes for in vivo medical Raman spectroscopy

Recent reports indicate that useful diagnostic information can be obtained from ex vivo tissue by using near-infrared Raman spectroscopy. A fiber-opti c-based Raman system has been constructed that can obtain spectra in vivo f rom tissue, typically in less than 30 s. The spectral details are limited b y the fluorescence and Raman signal generated in the silica delivery and co llection fibers. In this study, fiber-optic probes that are designed to sup press these confounding signals have been characterized and compared with a probe constructed of unfiltered silica fiber. These suppressing probes use d a novel design with "in-the-tip" filters, which also had optimized light collection efficiency. The spatial point response functions of the fibers w ere measured in air, water, and a tissue-simulating, optically turbid mediu m. Spectra from rabbit tissues were also collected with these probes to dem onstrate their performance.