Volumetric induction phase shift detection system for determining tissue water content properties

• US 7,638,341 B2
• Filed: 05/12/2006
• Issued: 12/29/2009
• Est. Priority Date: 06/09/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Rubinsky, Boris, Gonzalez, Cesar A.
• Primary Examiner(s): WALLENHORST, MAUREEN
• Application Number:
  US11/664,755
• Publication Number:
  US 20080224688A1
• Time in Patent Office: 1,327 Days
• Field of Search: 436/63, 436/149, 436/174, 436/183, 422/68.1, 422/82.01, 422/82.02, 435/40.5, 600/407, 600/422, 600/437, 600/438, 600/442, 600/454, 600/456, 600/547, 324/76.77, 324/694, 607/62
• US Class Current: 436/149
• CPC Class Codes: A61B 2562/143 for coupling microwaves
• CPC Class Codes: A61B 5/02042 Determining blood loss or bleeding, e.g. during a surgical procedure
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• 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 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/413 Monitoring transplanted tissue or organ, e.g. for possible rejection reactions after a transplant
• CPC Class Codes: A61B 5/4244 liver
• CPC Class Codes: A61B 5/443 Evaluating skin constituents, e.g. elastin, melanin, water
• CPC Class Codes: A61B 5/4519 Muscles A61B5/389, A61B5/224 take precedence
• CPC Class Codes: A61B 5/4869 Determining body composition
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: G01N 27/026 Dielectric impedance spectroscopy electrochemical impedance spectroscopy for measuring corrosion G01N17/02
• CPC Class Codes: G01R 33/34 Constructional details, e.g. resonators , specially adapted to MR
• CPC Class Codes: G01R 33/36 Electrical details, e.g. matching or coupling of the coil to the receiver
• CPC Class Codes: G01R 33/4828 Resolving the MR signals of different chemical species, e.g. water-fat imaging
• CPC Class Codes: G01R 33/483 : with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy

Abstract

A method of determining the condition of a bulk tissue sample, by: positioning a bulk tissue sample between a pair of induction coils (or antennae); passing a spectrum of alternating current (or voltage) through a first of the induction coils (or antennae); measuring spectrum of alternating current (or voltage) produced in the second of the induction coils (or antennae); and comparing the phase shift between the spectrum of alternating currents (or voltages) in the first and second induction coils (or antennae), thereby determining the condition of the bulk tissue sample. An apparatus for determining the condition of a bulk tissue sample, having: a first induction coil (or antenna); a second induction coil (or antenna); an alternating current power supply connected to the first induction coil (or antenna), the alternating current power supply configured to generate a spectrum of currents (or voltage) in the first induction coil (or antenna); and a measurement system connected to the second induction coil (or antenna), wherein the measurement system is configured to measure a phase shift difference in the spectrum of currents (or voltages) between the first and second induction coils (or antennae) when the first and second induction coils (or antennae) are positioned on opposite sides of a tissue sample.

Claims

1. A method of identifying an abnormal tissue water content medical condition in a bulk tissue sample by determining an induction phase shift response across a frequency range from a plurality of measurements taken at different frequencies in the frequency range, comprising:

positioning a bulk tissue sample between a pair of induction coils or antennae, wherein the bulk tissue sample does not contact either of the induction coils or antennae;

passing a plurality of alternating currents or voltages of different frequencies in the frequency range, through a first of the induction coils or antennae;

measuring the alternating currents or voltages produced in the second of the induction coils or antennae;

comparing the induction phase shift between the plurality of frequencies of alternating currents or voltages in the first and second induction coils or antennae, thereby determining the induction phase shift response of the bulk tissue sample at the measured frequencies within the frequency range;

comparing the determined induction phase shift response of the bulk tissue sample at the measured plurality of frequencies in the frequency range to an induction phase shift response of a tissue sample that does not exhibit an abnormal tissue water content medical condition at the measured plurality of frequencies in the frequency range; and

then,

identifying an abnormal tissue water content medical condition in the bulk tissue sample based on the comparison.

2. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises:

detecting at least one abnormal tissue water content medical condition from the group consisting of edema, ischemia, bleeding, dehydration, water accumulation in the bulk tissue sample, extravasation, and disease.

3. The method of claim 1, wherein the bulk tissue sample is selected from the group consisting of brain tissue, lung tissue, heart tissue, muscle tissue, skin tissue, kidney tissue, cornea tissue, liver tissue, abdomen tissue, head tissue, leg tissue, arm tissue, pelvis tissue, chest tissue or trunk tissue.

4. The method of claim 1, wherein the frequency range of the alternating current is between 10 kHz and 10 GHz.

5. The method of claim 1, wherein the frequency range of the alternating current is between 1 MHz and 10 GHz.

6. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises detecting edema, ischemia, dehydration, or extravasation, in the tissue sample, and wherein the frequency range of the alternating current is between 1 MHz and 10 GHz.

7. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises detecting interperitoneal bleeding in the tissue sample, and wherein the frequency range of the alternating current is between 1 MHz and 10 GHz.

8. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises:

detecting internal bleeding in the bulk tissue sample at a plurality of frequencies within a frequency range of 1 MHz to 9 MHz.

9. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises:

detecting edema, internal bleeding or dehydration in the bulk tissue sample at a frequency of 300 Mhz to 10 GHz.

10. The method of claim 1, wherein identifying an abnormal tissue water content medical condition in the bulk tissue sample comprises:

detecting edema, internal bleeding or dehydration in the bulk tissue sample at a plurality of frequencies within a frequency range of 100 Mhz to 10 GHz.

11. The method of claim 1, wherein comparing the determined induction phase shift response of the bulk tissue sample at the measured plurality of frequencies in the frequency range to an induction phase shift response of a tissue sample that does not exhibit an abnormal tissue water content medical condition at the measured plurality of frequencies in the frequency range comprises:

detecting internal bleeding by observing an inverse U-type shaped waveform on a plot of induction phase shift versus frequency for the bulk tissue sample.

12. The method of claim 11, wherein the inverse U-type shaped waveform is centered around 1 GHz.

13. The method of claim 1, wherein comparing the determined induction phase shift response of the bulk tissue sample at the measured plurality of frequencies in the frequency range to an induction phase shift response of a tissue sample that does not exhibit an abnormal tissue water content medical condition at the measured plurality of frequencies in the frequency range comprises:

detecting edema by observing an inverse U-type shaped waveform on a plot of induction phase shift versus frequency for the bulk tissue sample.

14. The method of claim 13, wherein the inverse U-type shaped waveform is centered around 100 MHz.

15. A method of monitoring a change in tissue water content medical condition in a bulk tissue sample by determining induction phase shift response changes at a plurality of different frequencies in a frequency range over a period of time, comprising:

positioning a bulk tissue sample between a pair of induction coils or antennae, wherein the bulk tissue sample does not contact either of the induction coils or antennae;

passing a plurality of alternating currents or voltages of different frequencies in the frequency range, through a first of the induction coils or antennae;

measuring alternating currents or voltages produced in the second of the induction coils or antennae; and

comparing the induction phase shift between the plurality of alternating currents or voltages in the first and second induction coils or antennae thereby determining an induction phase shift response of the bulk tissue at the measured frequencies; and

repeatedly determining the induction phase shift response of the bulk tissue at the measured plurality of frequencies within the frequency range over a period of time, thereby determining a change in the tissue water content medical condition of the bulk tissue sample over time.

16. The method of claim 15, wherein determining the change in tissue water content medical condition of the bulk tissue sample over time comprises:

detecting a change over time in at least one tissue water content condition selected from the group consisting of edema, ischemia, bleeding, dehydration, water accumulation in the bulk tissue sample, extravasation, and disease.

17. The method of claim 15, wherein the bulk tissue sample is selected from the group consisting of brain tissue, lung tissue, heart tissue, muscle tissue, skin tissue, kidney tissue, cornea tissue, liver tissue, abdomen tissue, head tissue, leg tissue, arm tissue, pelvis tissue, chest tissue or trunk tissue.

18. An apparatus for identifying an abnormal tissue water content medical condition by determining the condition of a bulk tissue sample, comprising:

a first induction coil or antenna;

a second induction coil or antenna;

an alternating current power supply connected to the first induction coil or antenna, the alternating current power supply configured to generate a plurality of frequencies in a frequency range of currents or voltages in the first induction coil or antenna;

a measurement system connected to the second induction coil or antenna, wherein the measurement system is configured to measure an induction phase shift difference at the plurality of frequencies of currents or voltages between the first and second induction coils or antennae when the first and second induction coils or antennae are positioned on opposite sides of a tissue sample and the first and second induction coils do not contact the tissue sample; and

a baseline comparison system for presenting the measured induction phase shift difference as compared across a range of frequencies to a baseline induction phase shift difference of a tissue sample that does not exhibit an abnormal tissue water content medical condition across the range of frequencies.

19. The apparatus of claim 18, further comprising:

a system to identify an abnormal tissue water content medical condition by determining the phase shift between the plurality of measured alternating currents or voltages in the first and second induction coils or antennae.

20. The apparatus of claim 19, wherein the system to identify an abnormal tissue water content medical condition in the bulk tissue sample comprises:

a system configured to identify at least one of edema, ischemia, bleeding, dehydration, water accumulation in the bulk tissue sample, extravasation, and disease by analysis of the phase shift difference in the currents between the first and second induction coils or antennae.

21. The apparatus of claim 18, wherein the alternating current power supply produces a plurality of frequencies within a range of alternating currents with a frequency between 10 kHz and 10 GHz.

22. The apparatus of claim 18, wherein the alternating current power supply produces a plurality of frequencies within a range of alternating currents with a frequency between 1 MHz and 10 GHz.

23. The apparatus of claim 18, wherein the alternating current power supply comprises:

a function generator configured to generate an alternating current in the first induction coil or antenna having a frequency that changes in pre-programmed steps.

24. The apparatus of claim 23, wherein the function generator supplies an excitation signal of approximately 20 mA in the range of 1 to 8.5 MHz at pre-programmed steps.

25. The apparatus of claim 18, further comprising:

a first differential receiving amplifier connected to the first induction coil or antenna; and

a second differential receiving amplifier connected to the second induction coil or antenna.

26. The apparatus of claim 18, further comprising:

a dual-channel demodulator connected to the first and second induction coils or antennae; and

an analog-digital converter connected to the dual-channel demodulator.

27. The apparatus of claim 26, wherein the dual-channel demodulator comprises:

a mixer; and

a narrow band pass filter.

28. The apparatus of claim 18, wherein the measurement system repeatedly performs the measurements of an induction phase shift difference at a plurality of frequencies within the range of frequencies over a period of time and wherein the baseline comparison system presents data illustrating changes in tissue water content over a period of time.