US5020538A
Expired / Lapsed
US
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Low noise magnetoencephalogram system and method
Assignee: Sam Tech Inc
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Filing: 1989-11-14
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Granted: 1991-06-04
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Expires: 2009-11-14
Abstract
Abstract A magnetoencaphalogram (MEG) detects the neuromagnetic brain signals of a subject by bringing a set of magnetic sensors, preferably SQUIDs (superconducting quantum interference device), close to the scalp of the subject. The adverse effect of environmental magnetic noise is reduced by using a second set of magnetic sensors which are placed near the subject. The system includes a bandpass filter, to divide the signals from the various sensors into predetermined frequency bands, and a computer to provide a least squares noise component estimate of the noise from each brain wave sensor and to calculate therefrom a filtered brain wave signal having reduced noise.
Inventors
- 👤 Nelson H. Morgan
- 👤 Alan S. Gevins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:50
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/022; A; A61; A61B; A61B5/00; A61B5/24; A61B5/242; A61B5/245; G06; G06F; G06F2218/00; G06F2218/02; Y; Y10; Y10S; Y10S128/00; Y10S128/901
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
208 words
A low noise magnetoencephalogram (MEG) system in an environment having magnetic activity, the system being for the detection of brain neuromagnetic activity of a human subject, including: a first plurality of magnetic sensor means at least part of each sensor means being adapted to be positioned adjacent the head of a subject to detect neuromagnetic brain signals; a plurality of brain signal channels, each brain signal channel connected to one of said first magnetic sensor means; a second plurality of magnetic sensor means to detect signals from environmental magnetic activity; a plurality of environmental noise reference channels, each reference channel being connected to one of said second magnetic sensor means; a bandpass filter means, connected to the brain signal channels and the reference channels to separate said brain signals and environmental signals into a plurality of predetermined frequency bands and reject said signals not within said predetermined frequency bands; computer transformation means which act separately on each of said frequency bands to provide a least squares noise component estimate of the noise component present in each brain signal channel; computer calculation means to algebraically subtract said least square noise component estimate from the signals in each brain wave channel thereby providing a filtered brain signal having reduced noise.
Claim 2
Dependent Claim
208 words
A low noise magnetoencephalogram (MEG) system in an environment having magnetic activity, the system being for the detection of brain neuromagnetic activity of a human subject, including: a first plurality of magnetic sensor means at least part of each sensor means being adapted to be positioned adjacent the head of a subject to detect neuromagnetic brain signals; a plurality of brain signal channels, each brain signal channel connected to one of said first magnetic sensor means; a second plurality of magnetic sensor means to detect signals from environmental magnetic activity; a plurality of environmental noise reference channels, each reference channel being connected to one of said second magnetic sensor means; a bandpass filter means, connected to the brain signal channels and the reference channels to separate said brain signals and environmental signals into a plurality of predetermined frequency bands and reject said signals not within said predetermined frequency bands; computer transformation means which act separately on each of said frequency bands to provide a least squares noise component estimate of the noise component present in each brain signal channel; computer calculation means to algebraically subtract said least square noise component estimate from the signals in each brain wave channel thereby providing a filtered brain signal having reduced noise.
Claim 3
Dependent Claim
23 words
A magnetoencephalogram (MEG) system as in claim 1 wherein the transformation means uses a Householder transformation matrix to provide the least square estimate.
Claim 4
Dependent Claim
21 words
A magnetoencephalogram (MEG) system as in claim 1 the system comprises at least 5 brain signal channels and 4 reference channels.
Claim 5
Dependent Claim
19 words
A magnetoencephalogram (MEG) system as in claim 1 wherein said bandpass filter means include at least 4 bandpass filters.
Claim 6
Dependent Claim
21 words
A magnetoencephalogram (MEG) system as in claim 1 wherein each of the sensor means is a SQUID (superconducting quantum interference device).
Claim 7
Dependent Claim
166 words
A noise reduction method in a magnetoencephalogram (MEG) for the detection of human brain neuromagnetic activity of a subject in an environment having noise magnetic activity including: positioning a plurality of magnetic sensor means adjacent to the head of a subject to detect neuromagnetic brain signals; connecting a brain signal channel to each of said brain signal magnetic sensor means; positioning a plurality of magnetic sensor means to detect the environmental magnetic activity; connecting a reference channel to each of the environmental magnetic senor means; separating the signals from each of the channels into a plurality of frequency bands using a bandpass filter means connected to the brain signal channels and the reference channels; automatically providing a least squares estimate of the noise component present in each brain signal channel and applying said least squares estimate to each of said frequency bands; automatically algebraically subtracting said noise component estimate from the signals in each brain wave channel thereby providing a filtered brain signal having reduced noise.
Claim 8
Dependent Claim
166 words
A noise reduction method in a magnetoencephalogram (MEG) for the detection of human brain neuromagnetic activity of a subject in an environment having noise magnetic activity including: positioning a plurality of magnetic sensor means adjacent to the head of a subject to detect neuromagnetic brain signals; connecting a brain signal channel to each of said brain signal magnetic sensor means; positioning a plurality of magnetic sensor means to detect the environmental magnetic activity; connecting a reference channel to each of the environmental magnetic senor means; separating the signals from each of the channels into a plurality of frequency bands using a bandpass filter means connected to the brain signal channels and the reference channels; automatically providing a least squares estimate of the noise component present in each brain signal channel and applying said least squares estimate to each of said frequency bands; automatically algebraically subtracting said noise component estimate from the signals in each brain wave channel thereby providing a filtered brain signal having reduced noise.
Claim 9
Dependent Claim
34 words
A noise reduction method as in claim 6 wherein 3 brain signal channels are connected to 3 brain signal magnetic sensor means and 3 reference channels are connected to 3 environment magnetic sensor means.
Claim 10
Dependent Claim
20 words
A noise reduction method as in claim 6 and using a Householder transformation matrix to provide the least squares estimate.
Claim 11
Dependent Claim
23 words
A noise reduction method as in claim 6 wherein the frequencies within the bandpass range are divided into at least 4 frequency bands.
Claim 12
Dependent Claim
22 words
A noise reduction method as in claim 6 and including the step of locating the sensor means in a non-magnetically shielded room.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |