System and method for compensating for motion artifacts in a strong magnetic field
First Claim
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1. A method for eliminating a motion artifact signal in an electrocardiogram measurement of a subject in a strong magnetic field, comprising the steps of:
- (A) producing a predetermined signal which controllably modulates the flux density of a magnetic field while performing an electrocardiogram measurement of a subject in said magnetic field to produce a first electrocardiogram signal;
(B) using said predetermined modulation signal to extract a motion artifact signal from said first electrocardiogram signal; and
(C) subtracting said extracted motion artifact signal from said first electrocardiogram signal, thereby eliminating the motion artifact signal and creating an output electrocardiogram signal free of said motion artifact signal.
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Abstract
A system for monitoring an ECG during a patient examination in a strong magnetic field, such as that created by an MRI machine, which eliminates motion artifacts affecting the accurate reading of the ECG. The system modulates the strong magnetic field and then generates an error correction signal substantially equal to the motion artifact signal in timed relationship with the modulated signal that is subtracted from the measured ECG signal to produce a more accurate ECG signal.
92 Citations
9 Claims
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1. A method for eliminating a motion artifact signal in an electrocardiogram measurement of a subject in a strong magnetic field, comprising the steps of:
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(A) producing a predetermined signal which controllably modulates the flux density of a magnetic field while performing an electrocardiogram measurement of a subject in said magnetic field to produce a first electrocardiogram signal; (B) using said predetermined modulation signal to extract a motion artifact signal from said first electrocardiogram signal; and (C) subtracting said extracted motion artifact signal from said first electrocardiogram signal, thereby eliminating the motion artifact signal and creating an output electrocardiogram signal free of said motion artifact signal. - View Dependent Claims (2, 3)
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4. An apparatus for eliminating a motion artifact signal in an electrocardiogram measurement of a subject in a strong magnetic field apparatus which includes primary modulation coils for modulating said magnetic field, comprising:
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(A) means for performing an electrocardiogram measurement of a subject in a magnetic field and thereby producing a first electrocardiogram signal; (B) a modulation waveform generator for generating a predetermined modulation signal; (C) a modulation coil driver coupled to said modulation waveform generator and to the primary field modulation coils for supplying a current proportional to said predetermined modulation signal to said primary field modulation coils; (D) a sample and hold timing generator coupled to said modulation waveform generator for producing a first sampling signal and a second sampling signal in timed relationship with said predetermined modulation signal; (E) a first sample and hold circuit coupled to said sample and hold timing generator and to said electrocardiogram measurement means for sampling said first electrocardiogram signal in timed relationship with said first sampling signal to produce a first error correction signal; (F) a second sample and hold circuit coupled to said sample and hold timing generator and to said electrocardiogram measurement means for sampling said first electrocardiogram signal in timed relationship with said second sampling signal to produce a second error correction signal; (G) a first subtraction circuit coupled to said first sample and hold circuit and to said second sample and hold circuit for subtracting said first error correction signal from said second error correction signal, thereby creating an extracted motion artifact signal; and (H) a second subtraction circuit coupled to receive said motion artifact signal and said first electrocardiogram signal for subtracting said extracted motion artifact signal from said first electrocardiogram signal, thereby creating an output electrocardiogram signal free of said motion artifact signal. - View Dependent Claims (5, 6, 7, 8)
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9. An apparatus for eliminating a motion artifact signal in an electrocardiogram measurement of a subject in a strong magnetic field, comprising:
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(A) means producing a predetermined signal to controllably modulate the flux density of a strong magnetic field; (B) means for performing an electrocardiogram measurement of a subject in said strong magnetic field to produce a first electrocardiogram signal; (C) means for extracting a motion artifact signal from said first electrocardiogram signal using said predetermined signal; and (D) a subtraction circuit for subtracting said motion artifact signal from said first electrocardiogram signal, thereby creating an output electrocardiogram signal free of said motion artifact signal.
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Specification