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Abstract

A method of diagnosis of the type of tissue in an artery, including distinguishing artery wall from atheromateous plaque is described, in which a catheter with one or more optical fibers is enclosed at a distal end by an optical shield transparent to light radiation and wherein the proximal end of the catheter and optical fibers are coupled to a source of optical radiation. The catheter is inserted into an artery until the optical shield is brought into contact with a suspected arterial lesion or other tissue to be diagnosed. An optical fiber is selected and light coupled from the source at a wavelength of about 480 nm enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end out the optical shield and impineges on the suspected lesion. The scattered and fluorescence light is returned to the proximal end of the selected optical fiber, and is coupled to a spectral analyzer wherein the fluorescence or scattered light excited by said light is analyzed to determine if the material contacted by the optical shield and, in particular, the portion irradiated by the incident light from the selected optical fiber is healthy arterial tissue or plaque or other material. This determination is made by observing at the proximal end of the selected fiber the fluorescence excited by the light to analyze the spectral profile in the range of 520-610 nm, where peaks occur. A determination is made from the ratios of fluorescence peak heights at 550 nm and 600 nm and the valley at 580 nm, or by analyzing other fluorescence wavelengths, whether the tissue being analyzed is artery wall, plaque, blood, or other tissue.

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First Claim