Quantitative magnetoencephalogram system and method

A method of detecting and analyzing magnetic fields on the scalp of a subject arising from the subject's brain waves, by:

• (a) positioning or selecting a plurality of magnetic field detectors arranged in an array in a dewar tail;
• (b) bringing the dewar tail into close proximity to the subject's scalp and holding the subject's head at the dewar tail to prevent head movement;
• (c) using the magnetic field detectors to detect scalp magnetic fields and to generate analog signals therefrom;
• (d) amplifying and digitizing the analog signals to produce a set of digital MEG (Magnetoencephalogram) data corresponding to the analog signals from each magnetic field detector;
• (e) automatically, in a computer, statistically comparing features extracted from each set of digital MEG data taken under selected conditions or stimuli with mean values and SD's (Standard Deviations) in a normative MEG database, on a feature-by-feature basis, based upon QMEG (Quantitative Magnetoencephalogram) data from a normal group simultaneously or previously gathered under the same conditions or stimuli and with the brain activity MEG detectors of the normal group at the same locations as those of the subject, to obtain and assess QMEG values;
• (f) simultaneously with (b), using a plurality of EEG electrodes on the scalp of the subject to derive EEG signals;
• (g) amplifying and digitizing the EEG signals to produce sets of QEEG (Quantitative Electroencephalogram) data;
• and
• (h) automatically in the computer comparing each set of QEEG data with digital QEEG data from a normal group taken, simultaneously or previously, under the same conditions or stimuli.

A method of detecting and analyzing magnetic fields on the scalp of a subject generated by the subject's spontaneous or stimulus evoked brain activity, by:

• (a) positioning an array of a plurality of magnetic field detectors closely adjacent to the subject's scalp to detect and amplify the magnetic fields from selected areas of the scalp;
• (b) converting the detected magnetic field into sets of digital data, with each set being generated by a magnetic field detector;
• (c) automatically comparing, in a computer, the sets of digital data with a normative reference database of QEEG (Quantitative Electroencephalogram) features simultaneously or previously collected from normal subjects, the comparisons being on a feature-by-feature basis, and the normal subjects having generated the database using brain wave EEG detectors at the same relative locations on their scalps as the relative locations of the magnetic field detectors on the scalp of the subject, to compute a measure of the probability that the observed value is beyond normal limits (Z- or F-score);
• (d) deriving a discriminant score based on the comparisons of (c) by selecting, weighting and combining a number of said feature-by-feature comparisons;
• (e) combining the discriminant scores to derive probabilities that the subject is classed in a specific diagnostic category;
• (f) applying selected guardbands (rule-out levels) to the probabilities to classify the subject on the basis of the probabilities;
• and
• (g) displaying the classification of the subject.

The method of analyzing the brain waves of a human subject to determine the presence, absence, degree and type of magnetic evoked response abnormality, the method consisting of the steps, in sequence, of:

• (a) positioning a plurality of magnetic field detectors in an array proximate to the scalp of the subject, the detectors being positioned in the same relative positions over the scalp as at least some of the electrodes are positioned in the 10/20 system;
• automatically presenting a sequence of stimuli to the subject to evoke magnetic brain responses (MER) at the detectors;
• (b) detecting, amplifying, converting the amplified electromagnetic brain activity from each detector into digital data, averaging the digitized brain activity to provide a set of averaged magnetic evoked responses (AMERs) from the array;
• (c) decomposing each of the averaged magnetic evoked responses (AMER) by factor analysis, in which each AMER from each detector is compared to pre-formulated factor waveforms (or component shapes) stored in computer memory to determine the amount of power that each pre-formulated factor waveform contributes to said AMER to thereby produce a factor score aij, quantifying the contribution of each factor j to the AMER from any detector i;
• (d) subjecting the results of the said factor score to Z transform, wherein each of said factor scores is compared to the statistical parameters of a normative factor score, corresponding to a quantitative assessment of AMER morphology, thereby providing an estimate of the degree of abnormality of each of said AMER'S.

A magnetoencephalogram (MEG) system for detecting and analyzing magnetic fields on the scalp of a subject generated by the subject's brain activity, comprising:

• (a) an array of a plurality of magnetic field detectors adapted to be positioned closely adjacent the subject's scalp to detect and amplify magnetic fields from selected areas of the scalp;
• (b) means for converting the detected magnetic fields into sets of digital data, with each set being generated by a magnetic field detector;
• (c) computer means for automatically comparing quantitative features extracted from the sets of digital data with a normative reference database of such features simultaneously or previously collected from normal subjects, the comparisons being on a feature-by-feature basis, and the normal subjects having generated the database using EEG electrodes at the same relative locations on their scalps as the relative locations of the magnetic field detectors on the scalp of the subject;
• (d) computer means for deriving a discriminant score based on the comparisons of (c) by selecting, weighting, and combining a number of said feature-by-feature comparisons;
• (e) computer means for combining the discriminant scores to derive probabilities that the subject is classified in a specific diagnostic category;
• (f) computer means for applying selected guardbands (rule-out levels) to the probabilities to classify the subject on the basis of the probabilities;
• and
• (g) means for displaying the classification of the subject.

A magnetoencephalogram (MEG) system for analyzing the magnetic components of a human subject's brain activity which are evoked by stimuli to determine the abnormality or normality of the response morphology, the system consisting of:

• (a) a plurality of MEG magnetic-field detectors, i, a dewar tail containing the field detectors, means to bring the dewar tail proximate the scalp of the subject to detect the subject's brain activity, the detectors being positioned in the same relative positions over the scalp as at least some of the electrodes are positioned in the 10/20 system;
• stimuli means for automatically presenting a sequence of stimuli to the patient to evoke brain magnetic responses (MER) at the field detectors;
• (b) amplifier means for amplifying the MER's, A/D converter means for converting the amplified AMERs into digital data, averaging means for averaging the digital data to provide averaged magnetic evoked responses (AMERs) for analysis;
• (c) computer means having a computer memory and calculation means for analyzing the AMERs by factor analysis, said computer means comparing each AMER from each field detector i to pre-formulated factor wave forms, j, stored in the computer memory to determine the power that each pre-formulated factor waveform, j, contributes to the AMER from detector i producing a factor score aij quantifying the contribution of each factor to the AMER from any field detector i;
• (d) computer means for subjecting said factor score, aij, to Z-transform, Zij, or F-value, Fij, automatically comparing each of said factor scores to the statistical parameters of a normative factor score database stored in the computer memory to produce a statistical assessment enabling a determination of response normality versus the degree of abnormality of morphology, and
• (e) display means to display the said normality and degree of abnormality.