Tissue diagnostic system

• US 6,026,323 A
• Filed: 09/23/1997
• Issued: 02/15/2000
• Est. Priority Date: 03/20/1997
• Status: Expired due to Fees

• Current Assignee: Polartechnics Ltd.
• Original Assignee: Polartechnics Ltd.
• Inventors: Thompson, Richard, Edwards, Neil, Bull, David, Smith, Megan, Skladnev, Victor, Wunderman, Irwin, Smart, Gregory, Rowe, Stephen
• Primary Examiner(s): Jaworski, Francis J.
• Assistant Examiner(s): Imam, Ali M.
• Application Number:
  US08/934,152
• Time in Patent Office: 875 Days
• Field of Search: 600/426, 600/407, 600/547, 600/591, 600/548, 607/901
• US Class Current: 600/547
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/0088 for oral or dental tissue
• CPC Class Codes: A61B 5/05 Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves impedance plethysmography A61B5/0295; measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4331 of the cervix A61B5/435 takes precedence
• CPC Class Codes: A61B 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

A probe type instrument to characterize tissue type that combines optical and electrical tests in a single device capable of providing data of both types almost simultaneously from very small, e.g. 3-10 mm diameter, areas of tissue surface. Key to this approach is an instrument capable of making almost simultaneous electrical and optical measurements on the same small areas of tissue, before being moved to scan adjacent tissue areas. In the preferred operation of the system fourteen measurement cycles are performed per second and each measurement involves a complex sequence of events, including (1) three optical and fifteen electrical tissue stimulations with subsequent detection, filtering and digitization of the tissue response; (2) extraction of specific parameters from the optical and electrical signals; (3) checking for errors, and subsequent classification of the extracted parameters into various tissue type categories; and (4) feedback to the system operator. Thus on the order of 15,000 measurements are made per one minute patient examination.

Claims

1. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein the parameters in said parameter group are not associated on a one-to-one basis with the sequential current pulses in said current pulse group.

2. An apparatus in accordance with claim 1 wherein successive groups of sequential current pulses are separated in time from each other by a time interval substantially greater than the time interval between the sequential current pulses within an individual group.

3. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein, for any current pulse for which a tissue response is desired, multiple measurements of the tissue potential are taken during decay of the potential following application of the current pulse,

wherein at least two parameter values are derived during the potential decay following each current pulse for which a tissue response is desired,

wherein each of said at least two parameter values is derived from several of the multiple measurements taken during decay of the current pulse for which a tissue response is desired,

wherein said processor categorizes any tissue surface area in accordance with at least two parameter values derived during the potential decay following each of at least two current pulses, and wherein said at least two current pulses are separated by at least one other current pulse the tissue response to which is not used by said processor to categorize the tissue to which said current pulses are applied.

4. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein, for any current pulse for which a tissue response is desired, multiple measurements of the tissue potential are taken during decay of the potential following application of the current pulse,

wherein at least two parameter values are derived during the potential decay following each current pulse for which a tissue response is desired, and

wherein said probe tip has at least three electrodes for applying current pulses to a selected tissue surface area with non-overlapping current pulses flowing between different groups of said electrodes, corresponding current pulse application and measurement cycles occurring for different groups of said electrodes, and corresponding ones of the at least two parameter values derived following the current pulses for different groups of said electrodes being combined for the categorization of said tissue surface area by said processor.

5. An apparatus in accordance with claim 4 wherein categorization of a tissue surface area by said processor is deemed unreliable if the difference between any two corresponding parameter values derived following the current pulses for different groups of said electrodes exceeds a threshold value.

6. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein, for any current pulse for which a tissue response is desired, multiple measurements of the tissue potential are taken during decay of the potential following application of the current pulse,

wherein at least two parameter values are derived during the potential decay following each current pulse for which a tissue response is desired, and

wherein said probe tip has at least three electrodes for applying current pulses to a selected tissue surface area with non-overlapping current pulses flowing between different groups of said electrodes, corresponding current pulse application and measurement cycles occurring for different groups of said electrodes, and said electrodes are connected in sequential groups to apply sequential current pulses to a selected tissue surface area such that electrode degradation by electrochemical effects is minimized.

7. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein said probe tip having electromagnetic radiation transmitting components to perform optical measurements on the selected tissue surface area, and multiple interspersed optical and electrical measurements are performed on the same tissue surface area selected by said probe.

8. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein the charge dissipation in the tissue volume underneath a selected tissue surface area is not complete by the time the next sequential current pulse is applied so that the categorizations of selected tissue surface areas are functions of the particular order of the electrical measurements.

9. An apparatus in accordance with claim 8 wherein successive groups of sequential current pulses are separated in time from each other by a time interval substantially greater than the time interval between sequential current pulses within an individual group so that the categorizations of successive selected tissue surface areas are substantially independent of each other.

10. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein the charge dissipation in the tissue volume underneath a selected tissue surface area is not complete by the time the next sequential current pulse is applied so that the categorizations of selected tissue surface areas are functions of the timings between sequential current pulses.

11. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said circuit for deriving said group of parameter values performs measurements on a selected tissue surface area by using a low-impedance probe whose influence on the decay of the potential in the underlying tissue volume following application of a current pulse is sufficiently great that valid categorization of a selected tissue surface area requires use of a comparable probe during the prior derivation of said catalog of tissue types.

12. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said probe tip further having optically coupled to it at least one light-emitting diode and a detector for detecting the light scattered back from the selected tissue surface area, the apparatus further comprising a circuit for measuring the bandgap potential of the light-emitting diode and adjusting accordingly the gain of the amplifier handling the signal from said detector to compensate for temperature fluctuations.

13. An apparatus in accordance with claim 12 wherein multiple interspersed optical and electrical measurements are performed on the same tissue surface area selected by said probe, and the bandgap potential of said at least one light-emitting diode is measured during the course of deriving values for said group of parameters.

14. An apparatus in accordance with claim 13 wherein said probe tip has at least three electrodes for applying current pulses to a selected tissue surface area with non-overlapping current pulses flowing between different groups of said electrodes, corresponding current pulse application and measurement cycles occurring for different groups of said electrodes, and all of said electrodes are connected together electrically during the intervals between said sequential current pulses.

15. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said probe tip further having optically coupled to it at least one light-emitting diode and a detector for detecting the light scattered back from the selected tissue surface area, the apparatus further comprising a circuit for measuring the bandgap potential of the light-emitting diode and adjusting accordingly the magnitude of the current pulses fed to the LED to compensate for temperature fluctuations.

16. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein said probe tip further having optically coupled to it at least one light-emitting diode, and a detector present at the probe tip for detecting the light scattered back from the selected tissue surface area, and wherein said detector receives light directly from said light-emitting diode and provides a signal proportional to the light output from said LED, and said apparatus further comprises an amplifier whose gain is changed in response to said signal to compensate for changes in the efficiency of said LED.

17. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein said probe tip further having optically coupled to it at least one light-emitting diode, and a detector present at the probe tip for detecting the light scattered back from the selected tissue surface area, and wherein said detector receives light directly from said light-emitting diode and provides a signal proportional to the light output from said LED, and said apparatus further comprises means to change the magnitude of a current pulse fed to said LED in response to said signal.

18. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as piecewise linear functions of a second parameter and associated with a degree of tissue abnormality, said transformed parameter comprising an integral of a portion of said parameter values for preselected time intervals and said second parameter comprises time.

19. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as piecewise linear functions of a second parameter and associated with a degree of tissue abnormality, said transformed parameter comprising the slope and intercept of the log voltage and said second parameter comprises inverse time.

20. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as piecewise linear functions of a second parameter and associated with a degree of tissue abnormality, said transformed parameter comprising the slope and intercept of the log voltage and said second parameter comprising log time.

21. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as piecewise linear functions of a second parameter and associated with a degree of tissue abnormality, said transformed parameter comprising arithmetic transformation of the parameter to diminish a predetermined obscuration effect of some artifact of, or noise source within the system and said second parameter comprising time.

22. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as piecewise linear functions of a second parameter and associated with a degree of tissue abnormality, said transformed parameter comprising voltage at the start of the relaxation curve and said second parameter comprising current.

23. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed parameters of the inrush current as piecewise linear functions of parameters of a relaxation curve.

24. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as integrals of parameter values over voltage intervals and associated with a degree of tissue abnormality.

25. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as integrals of parameter values over current intervals and associated with a degree of tissue abnormality.

26. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area, wherein said parameter values are transformed as magnitudes of offsets of parameter values and associated with a degree of tissue abnormality.

27. An apparatus for categorizing biological tissue whose surface area is selected by contact comprising:

a probe tip having an end surface that contacts said tissue surface area,

a potential source for applying a group of sequential current pulses from said probe tip to each of successively selected tissue surface areas, the sequential pulses within each group occurring at a rate fast enough so that they are applied to substantially the same tissue surface area,

a circuit for deriving values for a group of parameters indicative of the response to the group of sequential current pulses applied to each selected tissue surface area,

a memory adapted to store a catalog of tissue types associated with respective subsets of groups of parameter values, and

a processor for comparing the group of parameter values indicative of the response of a selected tissue surface area with the stored subsets of groups of parameter values to categorize said tissue surface area,

wherein, for any current pulse for which a tissue response is desired, multiple measurements of the tissue potential are taken during decay of the potential following application of the current pulse,

wherein at least two parameter values are derived during the potential decay following each current pulse for which a tissue response is desired, and

wherein said probe tip has at least two electrodes for applying current pulses to a selected tissue surface area and the polarity of said electrodes are reversed from time to time such that electrode degradation by electrochemical effects is reduced.