Apparatus and method for obtaining spectrally resolved spatial images of tissue

• US 5,125,404 A
• Filed: 11/21/1989
• Issued: 06/30/1992
• Est. Priority Date: 03/22/1985
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Kittrell, Carter, Feld, Michael S., Cothren, Robert M. Jr.
• Primary Examiner(s): HINDENBURG, MAX F
• Application Number:
  US07/440,100
• Time in Patent Office: 952 Days
• Field of Search: 128/6, 128/395-398, 128/633, 128/634, 128/664, 128/665, 606/15, 606/16
• US Class Current: 600/342
• CPC Class Codes: A61B 18/245 for removing obstructions in blood vessels or calculi
• CPC Class Codes: A61B 2018/2238 with means for selectively laterally deflecting the tip of the fibre
• 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: 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 laser catheter is disclosed wherein optical fibers carrying laser light are mounted in a catheter for insertion into an artery to provide controlled delivery of a laser beam for percutaneous intravascular laser treatment of atherosclerotic disease. A transparent protective shield is provided at the distal end of the catheter for mechanically displacing intravascular blood and protecting the fibers from the intravascular contents, as well as protecting the patient in the event of failure of the fiber optics. Multiple optical fibers allow the selection of tissue that is to be removed. A computer controlled system automatically aligns fibers with the laser and controls exposure time. Spectroscopic diagnostics determine what tissue is to be removed.

Claims

1. An optical system for generating a spectrally resolved spatial image of tissue comprising:

a catheter containing a plurality of optical fibers;

a laser coupled to the fibers to illuminate tissue with light;

a spectral analyzer for separating light returned by the tissue and transmitted along the fibers to said analyzer into different wavelengths;

a detector array for receiving the separated wavelengths of light, the detector array generating a spectrally resolved electronic representation of the received light; and

a computer for processing the separated light received by the detector such that the spectrally resolved light provides a displayable spatial image of the illuminated tissue.

2. The optical system of claim 1 wherein the optical fibers are arranged within the catheter in a fiber bundle.

3. The optical system of claim 1 wherein said spectral analyzer comprises a diffraction grating.

4. A method of obtaining spectrally resolved spatial images comprising the steps of:

positioning the distal end of an optical multifiber catheter in proximity with tissue to be imaged;

passing light through illuminating optical fibers onto the surface of tissue;

collecting light returned from said tissue and delivering it to a spectral analyzer with said optical fibers such that the light is spectrally dispersed and impinges on a detector array; and

processing signals from said detector array in a computer to generate a spectrally resolved spatial image of said tissue.

5. A spectrally resolved imaging system comprising:

a catheter containing a coherent optical fiber bundle;

a light source coupled to the fiber bundle to irradiate tissue positioned adjacent a distal end of the catheter such that radiation emitted by different portions of the tissue in response to the irradiation from the source is transmitted through the catheter;

a spectral analyzer that receives light emitted by the different portions of the tissue which is transmitted from the proximal end of the catheter such that the light emitted by each portion of tissue is spectrally resolved;

a detector to receive the spectrally resolved light for each portion of tissue; and

a data processor that processes the spectral information received by the detector for each portion of tissue to form a spectrally resolved spatial image for each portion of tissue.

6. The spectrally resolved imaging system of claim 5 wherein the detector comprises a detector array such that each wavelength of light falls on a single detector element of the array.

7. The spectrally resolved imaging system of claim 5 wherein the spectral analyzer comprises a plurality of filter elements.

8. The spectrally resolved imaging system of claim 5 wherein the spectral analyzer comprises a diffraction grating.

9. The spectrally resolved imaging system of claim 5 wherein the detector comprises an array of photodiodes.

10. A method of imaging tissue comprising:

positioning a distal end of a catheter adjacent to the tissue;

transmitting laser radiation along optical fibers within the catheter;

irradiating the tissue with the laser radiation projected from the distal end of the catheter;

collecting radiation returned from the tissue resulting from the irradiation thereof with the optical fibers such that the collected radiation is projected from the proximal end of the catheter;

spectrally resolving the radiation projected from the proximal end of the catheter;

forming a spectrally resolved spatial image of the tissue from the resolved radiation.

11. The method of imaging tissue of claim 10 further comprising spectrally resolving the radiation transmitted from the tissue with a diffraction grating.

12. The method of imaging tissue of claim 10 further comprising detecting the spectrally resolved radiation such that each wavelength of the radiation transmitted from the tissue by the fibers is directed onto a different portion of a detector array.

13. The method of imaging tissue of claim 10 wherein said spectrally resolving step further comprises directing the projected radiation a plurality of filters.

14. The method of imaging tissue of claim 10 further comprising detecting the spectrally resolved radiation to produce an imaging signal and processing the imaging signal to form the spectrally resolved spatial image.