Atherosclerotic identification

• US 5,046,501 A
• Filed: 01/18/1989
• Issued: 09/10/1991
• Est. Priority Date: 01/18/1989
• Status: Expired due to Fees

• Current Assignee: Wayne State University
• Original Assignee: Wayne State University
• Inventors: Crilly, Richard
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US07/298,576
• Time in Patent Office: 965 Days
• Field of Search: 128/395-398, 128/303.1, 128/633, 128/664, 128/665, 606/3
• US Class Current: 600/477
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: A61B 18/245 for removing obstructions in blood vessels or calculi
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61B 2018/00904 Automatic detection of target tissue
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence

Abstract

A method of identifying atherosclerotic plaque versus structurally viable tissue includes the steps of emitting a fluorescent beam at a single excitation wavelength of between 350 and 390 nm at a tissue and detecting and quantifying the emission spectrum of the emitted beam at critical points chosen to optimize the difference between atherosclerotic plaque and structurally viable tissue. The presence of the atherosclerotic plaque is distinguished from structurally viable tissue by the presence or absence of the intensity of emissions at the critical points of optimum distinguishing wavelengths. 8

Claims

1. A method of identifying atherosclerotic plaque versus structurally viable tissue, said method including the steps of:

emitting a beam of light at a single excitation wavelength of between 350 an 390 nm at a tissue;

detecting an quantifying the fluorescence emission spectrum of the emitted beam at critical points of optimum distinguishing emission from atherosclerotic plaque and structurally viable tissue; and

distinguishing the presence of atherosclerotic plaque from structurally viable tissue by the presence of absence of the quantity of intensity of emissions at the critical points of optimum distinguishing emission.

2. A method as set forth in claim 1 wherein said distinguishing step is reduced to a single judgement parameter by comparing the ratio of the quantity of the intensity of emission of at least two of the critical points of optimum distinguishing emission from atheroscleric plaque tissue and two critical points from normal structural tissues against a standard compilation of ratios of normal and atherosclerotic tissue, wherein a threshold limit for normal tissue, is used in identifying atherosclerotic tissue.

3. A method as set forth in claim 2 wherein the threshold is set by data at the 99.9 confidence limit of the variation in a contrast function for structurally viable tissue.

4. A method as set forth in claim 2 wherein critical points of optimum distinguishing emission from the atherosclerotic plaque are 570 and 600 nm and from the normal structural tissue at 480 and 500 nm using an excitation wavelength of 370 nm.