Tissue discrimination and applications in medical procedures

• US 20040181165A1
• Filed: 03/29/2004
• Published: 09/16/2004
• Est. Priority Date: 05/18/2000
• Status: Active Grant

• Current Assignee: Nuvasive Incorporated
• Original Assignee: Nuvasive Incorporated
• Inventors: Stone, Corbett W., Foley, Kevin T., Hoey, Michael F.
• Granted Patent: US 7,050,848 B2
• Time in Patent Office: Days
• US Class Current: 600/547
• CPC Class Codes: A61B 17/7001 Screws or hooks combined with longitudinal elements which do not contact vertebrae A61B17/7058 takes precedence
• CPC Class Codes: A61B 18/02 by cooling, e.g. cryogenic techniques devices for cooling specific reflex points of the body within cell-life limits A61H39/06
• CPC Class Codes: A61B 18/04 by heating by applying electromagnetic radiation A61B18/18; hyperthermia using electric or magnetic fields, radiation or ultrasound A61N
• CPC Class Codes: A61B 2017/00022 Sensing or detecting at the treatment site
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 5/4893 Nerves

Abstract

A system and method for discriminating tissue types, controlling the level of therapy to tissue, and determining the health or a known tissue by measuring the characteristics an electrical signal applied to conductive element located within or by the tissue. Additionally, the system and method may be used for determining whether the conductive tip of a pedicle probe or pedicle screw is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue, whether the conductive tip of a cannula is located adjacent to one of nerve tissue and annulus tissue, and whether the conductive tip of a cathode is located adjacent to one of nerve tissue and prostate gland tissue.

Claims

1. A method of determining whether a conductive element of a probe is located adjacent to a characterized body tissue comprising the steps of:

a) applying an electrical signal to the conductive element;

b) determining characteristics of the applied signal, including a phase angle; and

c) determining whether the conductive element of a probe is located adjacent to a characterized body tissue based on the phase angle of the applied signal, wherein said characterized body tissue comprises one of cortical bone, cancellous bone, or cortical bone near the boundary with soft tissue.

2. The method of claim 1, wherein the determined characteristics of the signal include an impedance of the signal through the tissue.

3. The method of claim 1, wherein the probe comprises one of a cannula and a cathode.

4. The method of claim 1, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

5. The method of claim 1, wherein step c) includes determining whether the conductive element of a probe is located adjacent to said tissue based on the determined characteristics and frequency of the resulting signal.

6. The method of claim 1, wherein the conductive element is an electrode.

7. The method of claim 1, wherein the conductive element includes a pair of electrodes and the signal is passed between said electrodes.

8. The method of claim 1, wherein the signal is an electrical signal having a sliding frequency.

9. An article of manufacture for use in determining whether a conductive element of a probe is located adjacent to a characterized body tissue, the article of manufacture comprising computer readable storage media including program logic embedded therein that causes control circuitry to perform the steps of:

a) applying a signal to the conductive element;

b) determining characteristics of the applied signal, including a phase angle; and

c) determining whether the conductive element of a probe is located adjacent to a characterized tissue based on the phase angle of the applied signal, wherein said characterized body tissue comprises one of cortical bone, cancellous bone, or cortical bone near the boundary with soft tissue.

10. The article of manufacture of claim 9, wherein the determined characteristics of the signal further include an impedance of the signal through the tissue.

11. The article of manufacture of claim 9, wherein the probe comprises one of a cannula and a cathode.

12. The article of manufacture of claim 9, wherein step a) applies signals having a range of predetermined frequencies to the conductive element.

13. The article of manufacture of claim 9, wherein step c) includes determining whether the conductive element of a probe is located adjacent to said tissue based on the determined characteristics and frequency of the resulting signal.

14. The article of manufacture of claim 9, wherein the conductive element is an electrode.

15. The article of manufacture of claim 9, wherein the conductive element includes a pair of electrodes and the signal is passed between said electrodes.

16. The article of manufacture of claim 9, wherein the signal is an electrical signal having a sliding frequency.

17. An apparatus for use in determining whether a conductive element of a probe is located adjacent to a characterized body tissue, the apparatus including:

a) means for applying a signal to the conductive element

b) means for determining characteristics of the applied signal, including a phase angle of the signal; and

c) means for determining whether the conductive element of a probe is located adjacent to a characterized body tissue based on the phase angle of the applied signal, wherein said characterized body tissue comprises one of cortical bone, cancellous bone, or cortical bone near the boundary with soft tissue.

18. The apparatus of claim 17, wherein the determined characteristics of the signal include an impedance of the signal through the tissue.

19. The apparatus of claim 17, wherein the probe comprises one of a cannula and a cathode.

20. The apparatus of claim 17, wherein means for applying a signal includes means for applying signals having a range of predetermined frequencies to the conductive element.

21. The apparatus of claim 17, wherein the means for determining whether the conductive element of a probe is located adjacent to said tissue includes means for determining whether the conductive element of a probe is located adjacent to said tissue based on the determined characteristics and frequency of the signal.

22. The apparatus of claim 17, wherein the conductive element is an electrode.

23. The apparatus of claim 17, wherein the conductive element includes a pair of electrodes and the signal is passed between said electrodes.

24. The apparatus of claim 17, wherein the signal is an electrical signal having a sliding frequency.