Systems and methods of molecular spectroscopy to provide for the diagnosis of tissue

• US 6,697,665 B1
• Filed: 08/11/1994
• Issued: 02/24/2004
• Est. Priority Date: 02/26/1991
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Rava, Richard P., Feld, Michael S., Baraga, Joseph J.
• Primary Examiner(s): Smith, Ruth S.
• Application Number:
  US08/288,990
• Time in Patent Office: 3,484 Days
• Field of Search: 600/473, 600/475, 436/63, 436/171, 436/172, 356/301
• US Class Current: 600/475
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the 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 5/0086 using infrared radiation
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: G01N 2021/656 Raman microprobe
• CPC Class Codes: G01N 21/65 Raman scattering

Abstract

Systems and methods for spectroscopic diagnosis and treatment are employed which utilize molecular spectroscopy to accurately diagnose the condition of tissue. Infrared Raman spectrscopy and infrared attenuated total reflectance measurements are performed utilizing a laser radiation source and a fourier transform spectrometer. Information acquired and analyzed in accordance with the invention provides accurate details of biochemical composition and pathologic condition.

Claims

1. A method of spectroscopic diagnosis of tissue comprising:

irradiating a subsurface portion of atherosclerotic tissue within a vascular lumen to be diagnosed with radiation having a frequency within the infrared range transmitted through a fiber optic cable;

detecting light emitted by the portion of atherosclerotic tissue in response to the radiation, the light having a plurality of Raman shifted frequencies in a range of 750 cm<sup>−

1</sup> to 1750 cm<sup>−

1</sup> that are different from the irradiating frequency; and

analyzing the plurality of Raman shifted frequencies of detected light to diagnose the tissue including the step of comparing the detected light with reference data to determine the presence of a fibrous tissue cap overlying a calcified layer.

2. The method of spectroscopic diagnosis of claim 1 wherein the detecting step further comprises collecting the emitted light through the fiber optic cable.

3. The method of spectroscopic diagnosis of claim 2 wherein the coupling step further comprises providing a catheter for insertion into body lumens.

4. The method of spectroscopic diagnosis of claim 2 wherein the fiber optic cable receives light emitted by the tissue and transmits the emitted light to a spectroscopic analysis system.

5. The method of spectroscopic diagnosis of claim 4 further comprising providing a fourier transform spectrometer to receive the emitted light.

6. A method of spectroscopic diagnosis of arterial tissue comprising:

positioning a catheter containing a light transmitting fiber optic cable adjacent to a portion of tissue within an artery to be diagnosed;

irradiating the portion of tissue with radiation having a frequency within the infrared range;

collecting light emitted by the portion of tissue in response to the radiation with the catheter, the light having a plurality of Raman shifted frequencies different from the irradiating frequency;

transmitting the collected light to a proximal end of the catheter;

detecting the collected light including the plurality of Raman shifted frequencies with a detector in a range of 750 cm<sup>−

1</sup> to 1750 cm<sup>−

1</sup>; and

analyzing the plurality of Raman shifted frequencies of detected light received at the proximal end to diagnose the tissue including the step of comparing the detected light with reference data to determine the presence of a fibrous tissue cap overlying a calcified layer.

7. The method of spectroscopic diagnosis of claim 6 wherein the fiber optic cable receives light emitted by the tissue and transmits the emitted light to a spectroscopic analysis system.

8. The method of spectroscopic diagnosis of claim 7 further comprising providing a fourier transform spectrometer.