Volumetric Induction Phase Shift Detection System for Determining Tissue Water Content Properties

• US 20080224688A1
• Filed: 05/12/2006
• Published: 09/18/2008
• 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.
• Granted Patent: US 7,638,341 B2
• Time in Patent Office: Days
• US Class Current: 324/76.77
• 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 determining the condition of a bulk tissue sample, comprising:

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 a 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.

2. The method of claim 1, wherein the first and second induction coils or antennae do not contact the bulk tissue sample.

3. The method of claim 1, wherein determining the condition of the bulk tissue sample comprises:

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

4. 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.

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

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

7. The method of claim 1, wherein determining the condition of the bulk tissue sample comprises detecting edema, ischemia, dehydration, extravasation, in the tissue sample, and wherein the spectrum of frequency of the alternating current is between 100 kHz to 10 GHz.

8. The method of claim 1, wherein determining the condition of the bulk tissue sample comprises detecting interperitoneal bleeding in the tissue sample, and wherein the spectrum of frequency of the alternating current is between 100 kHz to 10 GHz

9. A method of determining changes in the condition of a bulk tissue sample over time, comprising:

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 a 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 over time, thereby determining a change in the condition of the bulk tissue sample over time.

10. The method of claim 9, wherein the first and second induction coils or antennae do not contact the bulk tissue sample.

11. The method of claim 9, wherein determining the change in the condition of the bulk tissue sample over time comprises:

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

12. The method of claim 9, 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.

13. An apparatus for 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 spectrum of currents or voltages 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.

14. The apparatus of claim 13, further comprising:

a system to compare the phase shift between the alternating currents or voltages in the first and second induction coils or antennae to determine the condition of the bulk tissue sample.

15. The apparatus of claim 13, wherein the alternating current power supply produces a spectrum of alternating currents with a frequency between 10 kHz and 10 GHz.

16. The apparatus of claim 13, wherein the alternating current power supply produces a spectrum of alternating currents with a frequency between 1 MHz and 10 GHz.

17. The apparatus of claim 14, wherein the system to determine the condition of the bulk tissue sample comprises:

a system configured to detect 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 pair of induction coils or antennae.

18. The apparatus of claim 13, 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.

19. The apparatus of claim 18, 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.

20. The apparatus of claim 13, 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.

21. The apparatus of claim 13, 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.

22. The apparatus of claim 21, wherein the dual-channel demodulator comprises:

a mixer; and

a narrow band pass filter.