Visible fluorescence spectral diagnostic for laser angiosurgery

• US 4,718,417 A
• Filed: 03/22/1985
• Issued: 01/12/1988
• Est. Priority Date: 03/22/1985
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Willett, Robert L., Kenny, Leo T., de los Santos-Pacheco, Cynthia, Feld, Michael S., Kittrell, Carter
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): SHAY, DAVID M
• Application Number:
  US06/715,131
• Time in Patent Office: 1,026 Days
• Field of Search: 128/633, 128/634, 128/653, 128/656, 128/658, 128/664, 128/665, 128/303.1, 128/362, 128/395-398
• US Class Current: 606/7
• CPC Class Codes: A61B 1/00183 for variable viewing angles
• CPC Class Codes: A61B 1/0056 the insertion parts being asymmetric, e.g. for unilateral bending mechanisms
• 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 2017/00061 spectrum
• CPC Class Codes: A61B 2017/22038 with a guide wire
• CPC Class Codes: A61B 2017/22051 with an inflatable part, e.g. balloon, for positioning, blocking, or immobilisation A61B2017/22048, A61B2017/3486 take precedence
• CPC Class Codes: A61B 2017/22059 transparent
• CPC Class Codes: A61B 2017/22061 for spreading elements apart
• CPC Class Codes: A61B 2018/00636 Sensing and controlling the application of energy
• CPC Class Codes: A61B 2018/1861 with an instrument inserted into a body lumen or cavity, e.g. a catheter
• 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
• CPC Class Codes: A61B 90/39 Markers, e.g. radio-opaque or breast lesions markers
• CPC Class Codes: A61N 5/0601 Apparatus for use inside the body
• CPC Class Codes: G02B 6/3504 Rotating, tilting or pivoting the waveguides, or with the waveguides describing a curved path rotary joint G02B6/3628
• CPC Class Codes: G02B 6/3508 Lateral or transverse displacement of the whole waveguides, e.g. by varying the distance between opposed waveguide ends, or by mutual lateral displacement of opposed waveguide ends
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3516 : the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/3548 : 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/3598 : Switching means directly located between an optoelectronic element and waveguides, including direct displacement of either the element or the waveguide, e.g. optical pulse generation based on changing the optical properties of the medium G02F1/00; optical pulse generation in optical transmitters H04B10/508; optical pulse generation by controlling laser operation H01S3/00
• CPC Class Codes: G02B 6/4296 : coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources

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.

Claims

1. A method of diagnosis of the type of tissue in the artery, including distinguishing artery wall from atheromateous plaque, comprising the steps of:

(a) providing a catheter with one or more optical fibers in which the distal end of the catheter is enclosed by an optical shield transparent to light radiation and wherein the proximal end of the catheter and optical fibers may be coupled to a source of optical radiation wherein the radiation is capable of exciting fluorescence and scattering light;

(b) inserting said catheter into an artery until the optical shield is brought into contact with a suspected arterial lesion or other tissue to be diagnosed;

(c) selecting an optical fiber and coupling said light at a wavelength of about 480 nm from the light source to the proximal end of said optical fiber whereby the light enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end of said fiber out the optical shield and impinges on the suspected lesion, and the scattered and fluorescent 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;

(d) observing at the proximal end of the selected fiber the fluorescence excited by said light to analyze the spectral profile in the range 520-610 nm, where peaks occur;

(e) determine from 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.

2. The method of diagnosis of claim 1 wherein the light source is the 476 nm line of an argon ion laser.

3. The method of diagnosis of claim 1 wherein the peak signal amplitude at 600 nm is divided by the valley signal amplitude at 580 nm, and when the ratio is much larger than unity and closer to two, said tissue is determined to be healthy artery wall, and when the ratio is smaller and close to unity, said tissue is determined to be atherosclerotic plaque.

4. A method for treatment of arterial tissue or obstructions comprising the steps of:

(a) providing a catheter with a plurality of optical fibers in which the distal end of the catheter is enclosed by an optical shield transparent to light radiation and wherein the proximal end of the catheter and optical fibers may be coupled to a source of optical radiation of relatively high power and low power, the high power radiation being capable of removing tissue, and the low power radiation being capable of exciting fluorescence and scattering light, but not of removing tissue;

(b) inserting said catheter into an artery until the optical shield is brought into contact with a suspected arterial lesion;

(c) selecting an optical fiber and coupling the low power light at a wavelength of between about 430 to 530 nm from the light source to the proximal end of said optical fiber whereby the light enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end of said fiber out the optical shield and impinges on the suspected lesion, and the scattered and fluorescent 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;

(d) observing at the proximal end of the selected fiber the fluorescence excited by said light to analyze the spectral profile in the range 520-620 nm, where peaks occur;

(e) in the event it is determined that the material is to be removed, coupling the proximal end of said selected optical fiber to the source of relatively high power radiation and coupling said radiation to the proximal end of said selected optical fiber whereby such radiation is transmitted through said fiber to the distal end to irradiate a portion of the tissue;

(f) repeating the above steps until the lesion has been removed as needed.

5. The method of claim 4 wherein the low power light is 476 nm radiation from an argon ion laser.

6. A method of diagnosis of the type of tissue in an artery, including distinguishing artery wall from atheromateous plaque, comprising the steps of:

(a) inserting a catheter containing a multiplicity of optical fibers into an artery, said catheter and fibers having proximal and distal ends with an optical shield means on the distal end of the catheter having an optically transparent enclosure with a distal output surface located a fixed distance from the distal ends of the fibers and extending over the end of the catheter and a distal surface for displacing body fluid such that direct contact can be made by said distal surface with such tissue within the artery and a laser source of light coupled to at least one of said fibers at a proximal end;

(b) terminating said insertion when the optical shield is brought into contact with a suspected arterial lesion or other tissue to be diagnosed;

(c) selecting an optical fiber coupled to said laser source and coupling said light to the proximal end of said optical fiber whereby the light enters the proximal end of the optical fiber and is transmitted by the selected optical fiber to the distal end of said fiber out the optical shield and impinges on the suspected lesion to produce fluorescence and associated fluorescent light is returned to the proximal end of the selected optical fiber, and is coupled to a spectral analyzer wherein the fluorescent light is analyzed to determine if the material contacted by the optical shield and, in particular, the porton irradiated by the incident light from the selected optical fiber is healthy arterial tissue or plaque or other material, said analysis including;

(i) observing at the proximal end of the selected fiber the fluorescence excited by said light to analyze the spectral profile in the range 520-610 nm, where peaks occur; and

(ii) determining from ratios of fluorescence peak heights at about 550 nm and 600 nm and the valley at about 580 nm, whether the tissue being analyzed is artery wall, plaque, blood or other tissue.

7. The method of claim 6 wherein the laser light source emits light at wavelengths in a range between about 430 nm to 530 nm.

8. The method of claim 6 wherein less than 100 microwatts of power is used from said laser source to excite fluorescence.

9. The method of claim 6 including providing a beam splitter near the proximal end of the catheter to allow use of the same optical fiber for both delivery of incident light from the laser and return of fluorescent light to the spectral analyzer.

10. The method of diagnosis of claim 6 wherein the light source is the 476 nm line of an argon ion laser.

11. The method of claim 6 wherein the fluorescent light returned to the proximal end of the fiber forms a spectral information map of the tissue.