Catheter-delivered low resolution Raman scattering analyzing system for detecting lesions

• US 6,208,887 B1
• Filed: 06/24/1999
• Issued: 03/27/2001
• Est. Priority Date: 06/24/1999
• Status: Expired due to Fees

• Current Assignee: Prescient Medical, Inc.
• Original Assignee: Richard H. Clarke
• Inventors: Clarke, Richard H.
• Primary Examiner(s): Jeffery, John A.
• Application Number:
  US09/339,524
• Time in Patent Office: 642 Days
• Field of Search: 600/476, 600/478, 600/342, 606/2, 606/3, 606/10, 606/15, 356/301
• US Class Current: 600/476
• 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

The present invention provides low resolution Raman spectroscopic systems and methods for in-vivo detection and analysis of a lesion in a lumen of a subject. The system uses a multi-mode laser attached to a catheter in making in-vivo Raman spectroscopic measurements of the lumen. The system includes a light collector and/or a light dispersion element as well as a detector to measure spectral patterns that indicate the presence of the lesion. Based on the spectral response of the lumen, the presence (or absence) of a lesion can be determined. In addition, the components of the lesion can also be identified based on the unique Raman spectrum associated with each component.

Claims

1. A system for detecting the presence of a lesion in a lumen of a subject using low resolution Raman spectroscopy comprising:

a catheter comprising an excitation fiber through which multi-mode radiation can propagate to irradiate a target region of a lumen;

a multi-mode laser for irradiating the target region to produce a Raman spectrum consisting of scattered electromagnetic radiation;

a low resolution dispersion element positioned to receive and separate the scattered radiation into different wavelength components;

a detection array, optically aligned with the dispersion element for detecting at least some of the wavelength components of the scattered light; and

a processor for processing data from the detector array.

2. The system of claim 1, wherein the catheter further comprises a light directing element, and the excitation fiber has a first end coupled to the multi-mode laser, and a second end coupled to the light directing element to direct the laser radiation to the target region.

3. The system of claim 1, wherein the wavelength components are separated by a resolution ranging from about 10 cm to about 100 cm.

4. The system of claim 1, wherein the system has a resolution of between 30 cm and 50 cm, wherein the resolution is determined in part by the multi-mode laser and, in part by the dispersion element.

5. The system of claim 1, wherein the multi-mode laser produces laser radiation having a wavelength of between about 700 nm and about 2.4 μ

m.

6. The system of claim 1, wherein the multi-mode laser produces radiation having a line width of at least 2 nm.

7. The system of claim 1, wherein the multi-mode laser has a power between about 50 mW and about 1000 mW.

8. The system of claim 1, wherein the multi-mode laser comprises a 785 nm GaAs laser diode.

9. The system of claim 1, wherein the multi-mode laser has a full-width half-maximum of 30 cm.

10. The system of claim 1, wherein the processor includes a chemometric element for applying partial least squares analysis for extracting information from said Raman spectrum.

11. The system of claim 1, wherein the dispersion element is a low resolution diffraction grating.

12. The system of claim 1, wherein the dispersion comprises a monochromator.

13. The system of claim 1, wherein the detection array comprises a diode array detector.

14. The system of claim 1, wherein the system further includes a notched filter.

15. A method for detecting the presence of a lesion in a lumen of a subject using low resolution Raman spectroscopy comprising:

providing a catheter comprising an excitation fiber through which multi-mode radiation can propagate, the excitation fiber having a first end optically coupled to a multi-mode laser, and a second end positioned in optical alignment with a light directing element to direct radiation to a site within a lumen;

inserting the catheter into the lumen;

activating the multi-mode laser to irradiate the lumen to produce a Raman spectrum consisting of scattered electromagnetic radiation;

collecting a portion of the scattered radiation;

separating the collected radiation into different wavelength components using a low resolution dispersion element;

detecting at least some of the wavelength components of the scattered light using a detection array; and

processing the data from the detection array to detect the presence of a lesion.

16. The method of claim 15, further comprises identifying the components of the lesion from the data.

17. The method of claim 15, wherein the step of inserting a catheter into a lumen comprises inserting the catheter into a blood vessel.

18. The method of claim 15, wherein the step of detecting a lesion comprises detecting an atherosclerotic plaque.

19. The method of claim 16, wherein the step of identifying the components of a lesion comprises identifying components selected from the group consisting of cholesterol esters, calcium salts, free cholesterol, phospholipids and triglycerides.

20. The method of claim 15, wherein the step of processing further comprises applying a partial least squares analysis to extract chemometric information from the data.

21. The method of claim 15, wherein the step of separating and collecting the radiation comprises having a resolution of between 30 cm and 50 cm, wherein the resolution is determined in part by the multi-mode laser and, in part by the dispersion element.