Method for detecting fluid in cranuim via time varying magnetic field phase shifts

• US 10,335,054 B2
• Filed: 04/20/2015
• Issued: 07/02/2019
• Est. Priority Date: 01/19/2012
• Status: Active Grant

• Current Assignee: Cerebrotech Medical Systems, Inc.
• Original Assignee: Cerebrotech Medical Systems, Inc.
• Inventors: Wyeth, Richard Warren, Levinson, Mitchell Elliott
• Primary Examiner(s): Akar, Serkan
• Application Number:
  US14/690,985
• Publication Number:
  US 20150223722A1
• Time in Patent Office: 1,534 Days
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 2562/166 the sensor is mounted on a specially adapted printed circuit board
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• CPC Class Codes: A61B 2562/222 Electrical cables or leads therefor, e.g. coaxial cables or ribbon cables
• CPC Class Codes: A61B 2576/026 for the brain
• CPC Class Codes: A61B 5/0037 Performing a preliminary scan, e.g. a prescan for identifying a region of interest
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/031 Intracranial pressure
• 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 5/0522 Magnetic induction tomography
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 5/6803 Head-worn items, e.g. helmets, masks, headphones or goggles
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6831 Straps, bands or harnesses
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• 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 5/7246 : using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7257 : using Fourier transforms
• CPC Class Codes: A61B 5/7275 : Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7278 : Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 : Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 : for calculating health indices; for individual health risk assessment

Abstract

A diagnostic method for monitoring changes in a fluid medium in a patient'"'"'s head. The method includes positioning a transmitter at a first location on or near the patient'"'"'s head, the transmitter generates and transmits a time-varying magnetic field into a fluid medium in the patient'"'"'s head responsive to a first signal; positioning a receiver at a second location on or near the patient'"'"'s head offset from the transmitter, the receiver generates a second signal responsive to a received magnetic field at the receiver; transmitting a time-varying magnetic field into the fluid medium in the patient'"'"'s head in response to the first signal; receiving the transmitted magnetic field; generating the second signal responsive to the received magnetic field; and determining, a phase shift between the transmitted magnetic field and the received magnetic field for a plurality of frequencies of the transmitted time-varying magnetic field.

Claims

1. A method for monitoring intracranial fluid in a patient'"'"'s head, the method comprising:

placing a headset on the patient'"'"'s head, wherein the headset includes a first transmitter positioned at a first location on the headset, a second transmitter positioned at a second location on the headset offset from the first location, a receiver positioned at a third location on the headset offset from the first and second locations, and a processor comprising a field-programmable gate array;

providing a first signal to the first transmitter from the frequency synthesis field-programmable gate array, wherein providing the first signal includes;

producing, with the frequency synthesis field-programmable gate array, a square wave clock signal for generating a first time-varying magnetic field in the first transmitter and a sampling signal at an offset in frequency from the square wave clock signal; and

amplifying the square wave signal;

transmitting from the first transmitter, in response to the first signal, the first time-varying magnetic field through the intracranial fluid and toward the receiver;

receiving the first time-varying magnetic field with the receiver based on the sampling signal;

generating, with the receiver, a second signal responsive to the received first time-varying magnetic field;

transmitting the second signal from the receiver to the processor;

determining, with the processor of the headset, a first phase shift between the transmitted first time-varying magnetic field and the received first time-varying magnetic field for a plurality of frequencies of the transmitted first time-varying magnetic field;

providing a third signal to the second transmitter from the frequency synthesis field-programmable gate array;

transmitting from the second transmitter, in response to the third signal, a second time-varying magnetic field through the intracranial fluid and toward the receiver;

receiving the second time-varying magnetic field with the receiver;

generating, with the receiver, a fourth signal responsive to the received second time-varying magnetic field;

transmitting the fourth signal from the receiver to the processor;

determining, with the processor, a second phase shift between the transmitted second time-varying magnetic field and the received second time-varying magnetic field for a plurality of frequencies of the transmitted second time-varying magnetic field; and

determining, with the processor, an analysis of the intracranial fluid based on the first phase shift and the second phase shift.

2. The method of claim 1, further comprising converting the received first time-varying magnetic field and the received second time-varying magnetic field with an analog to digital converter coupled directly with the headset at or near the receiver.

3. The method of claim 1, wherein the analysis includes a change in the intracranial fluid;

and wherein the method further comprises generating a fifth signal, via the processor, responsive to determining that the change in the intracranial fluid has occurred.

4. The method of claim 1, wherein the first time-varying magnetic field and the second time-varying magnetic field are in a frequency range of 20 MHz to 300 MHz.

5. The method of claim 1, further comprising, before transmitting the first time-varying magnetic field, initiating the headset by transmitting a calibration magnetic field from at least one of the first transmitter or the second transmitter to the receiver while the headset is not coupled with the patient.

6. The method of claim 1, further comprising:

detecting motion of the patient with a motion detection member on the headset;

transmitting a fifth signal to the processor based on the detected motion; and

determining, using the processor, whether the determined analysis of the intracranial fluid was caused by the detected motion of the patient.

7. The method of claim 1, further comprising:

calculating, with the processor, a fast Fourier transform of samples of the transmitted and received first time-varying magnetic field and second time-varying magnetic field; and

determining the first phase shift and the second phase shift by comparing phase components of the calculated respective fast Fourier transforms.

8. The method of claim 1, wherein placing the headset on the patient'"'"'s head comprises positioning an elastic headband on the head, wherein the first and second transmitters and the receiver are mounted to the elastic headband, and wherein a first spacer is coupled with the first transmitter, a second spacer is coupled with the second transmitter, and a third spacer is coupled with the receiver so that the first spacer is disposed between the first transmitter and the patient'"'"'s head, the second spacer is disposed between the second transmitter and the patient'"'"'s head, and the third spacer is disposed between the receiver and the patient'"'"'s head, when the headband is positioned on the patient'"'"'s head.

9. The method as in of claim 1, further comprising recommending a treatment, based on the analysis of the intracranial fluid.

10. The method of claim 9, wherein recommending the treatment comprises recommending an amount of mannitol to be delivered to the patient to reduce an amount of the intracranial fluid.