Methods of molecular spectroscopy to provide for the diagnosis of tissue

• US 6,690,966 B1
• Filed: 10/22/1993
• Issued: 02/10/2004
• 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:
  US08/107,854
• Time in Patent Office: 3,763 Days
• Field of Search: 128/633, 128/634, 128/664, 356/301, 600/310, 600/311, 600/473, 600/475, 600/476-479
• US Class Current: 600/473
• 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 spectroscopy 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 of a patient comprising:

irradiating a portion of the tissue of a patient to be diagnosed with laser radiation directed onto the tissue through a fiber optic cable with a first frequency and then irradiating the same portion of tissue with a second frequency slightly shifted from the first frequency;

detecting light emitted by the portion of tissue in response to irradiation by the first frequency to generate a first spectrum of emitted light frequency components, detecting light emitted by the tissue in response to irradiation by the second frequency to generate a second spectrum of emitted light frequency components, and generating a difference spectrum from the first spectrum and the second spectrum by subtracting one from the other, the difference spectrum containing substantially the Raman shifted frequency components of the first spectrum and the second spectrum and detecting light emitted by the tissue with a charge coupled device that is optically coupled to a proximal end of the fiber optic cable, the device collecting the light for a period of 5 minutes or less, the light having a Raman shifted frequency component different from the first and second irradiating frequencies and further having background light components having shot noise levels below the level of the Raman light component;

removing the background light components from the detected light to leave substantially the Raman shifted frequency light components; and

analyzing the remaining detected light to diagnose a condition of the portion of tissue.

2. The method of claim 1 wherein the first and second irradiation frequencies have wavelengths of between 750 nm and 900 nm, and the second frequency is shifted from the first frequency by less than 50 cm⁻

1.

3. The method of claim 1 wherein the detecting step further comprises generating the first spectrum and the second spectrum of the emitted light frequency components with a spectrometer and detecting the first spectrum and the second spectrum with the charge coupled device.

4. The method of claim 3 further including the steps of providing a spectrometer comprising a single stage spectroscope.

5. The method of claim 3 further comprising electronically generating the difference spectrum with a computer from the first and second spectra detected with the charge coupled device.

6. The method of spectroscopic diagnosis of claim 1 wherein the detecting step further comprises generating a spectrum of the emitted light frequency components with a spectrometer and detecting the spectrum with the charge coupled device.

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 the spectrometer.

8. The method of spectroscopic diagnosis of claim 7 further comprising providing a single stage spectrometer.

9. The method of spectroscopic diagnosis of claim 6 further comprising an optical needle to which the radiation is coupled for delivery to the tissue.

10. The method of spectroscopic diagnosis of claim 6 further comprising detecting light reflected by the tissue and analyzing the reflected light to diagnosis the tissue.

11. The method of spectroscopic diagnosis of claim 1 further comprising providing a catheter, through which the fiber optic cable extends, for insertion into body lumens.

12. A method of spectroscopic diagnosis of tissue comprising:

irradiating a portion of tissue of a patient to be diagnosed with laser radiation having at least first and second irradiating frequencies in the infrared range that are directed through a fiber optic cable;

detecting light emitted by the portion of tissue in response to the laser radiation with a charge coupled device that is optically coupled to a proximal end of the fiber optic cable, the device collecting light from the portion of tissue for a period of 5 minutes or less, the detected light having a Raman shifted frequency component different from the first and second irradiating frequencies,

removing background components from the detected light to provide corrected Raman spectral data; and

analyzing the corrected Raman spectral data to diagnose a condition of the portion of the tissue.

13. The method of claim 12 further comprising collecting light emitted by the tissue for a period of eight seconds or less.

14. The method of claim 12 further comprising collecting light emitted by the tissue for a period of one second or less.

15. The method of claim 12 further comprising altering the frequency of the infrared radiation to alter a depth of penetration of the radiation into tissue.

16. The method of claim 12 further comprising altering an angle of incidence of the radiation relative to the portion of tissue to alter a depth of penetration of the radiation into the portion of tissue.