REDUCTION OF MRI INTERFERENCE FROM THE ELECTROCARDIOGRAM USING LEAD INFORMATION

• US 20150094561A1
• Filed: 05/15/2013
• Published: 04/02/2015
• Est. Priority Date: 05/24/2012
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Rey, Eduardo Mario, Lis, Bernard
• Granted Patent: US 10,231,671 B2
• Time in Patent Office: Days
• US Class Current: 600/411
• 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 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• 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: G01R 33/28 Details of apparatus provided for in groups G01R33/44 - G01R33/64
• CPC Class Codes: G01R 33/5673 Gating or triggering based on a physiological signal other than an MR signal, e.g. ECG gating or motion monitoring using optical systems for monitoring the motion of a fiducial marker

Abstract

A circuit (32) for use in an magnetic resonance (MR) system to reduce MR interference of a physiological signal S(f) includes a first summing/subtraction node (36), a high pass filter (40), and a second summing/subtraction node (42). The first summing/subtraction node (36)inputs a first signal (34) including radio frequency magnetic interference N(f) and a physiological signal S(f), and a second signal (38) including the physiological signal S(f) and an error signal E(f), and subtractively combines the second signal with the first signal to generate a difference signal N(f)−E(f). The high pass filter (40) filters the difference signal N(f)−E(f) from the first summing/subtraction node. The second summing/subtraction node (42) subtractively combines the first signal S(f)+N(f) (34) and the filtered signal H(f)*[N(f)−E(f)] from the high pass filter, and generates the second signal S(f)+E(f) (38).

Claims

1. A circuit for use in an magnetic resonance (MR) system to reduce MR interference of a physiological signal S(f), the circuit comprising:

a first summing/subtraction node which inputs a first signal including all interference components generated by the MRI scanner N(f) and a physiological signal S(f), and a second signal including the physiological signal S(f) and an error signal E(f), and which subtractively combines the second signal S(f)+E(f) with the first signal S(f)+N(f) to generate a difference signal N(f)−

E(f);

a high pass filter which filters the difference signal N(f)−

E(f) from the first surriminesulatraction node; and

a second summing ubtraction node which subtractively combines the first signal S(f)+N(f) and the filtered signal H(f) [N(f)−

E(f)] from the high pass filter, and generates the second signal S(f)+E(f).

2. The circuit according to claim 1, further including at least one of:

a low pass filter;

a slew-rate limit unit; and

an interpolation unit.

3. The circuit according to claim 1, wherein the first summing/subtraction node, the second summing/subtraction node, and the high pass filter each include an operational amplifier.

4. The circuit according to claim 1, wherein the physiological signal includes an electrocardiogram (ECG) signal.

5. The circuit according to claim 1, further including:

an analog to digital converter which converts the second signal to a digital signal.

6. The circuit according to claim 1, wherein the high pass filter includes a Sallen-Key filter.

7. The circuit according to claim 1, wherein the radio frequency magnetic resonance interference includes gradient pulse interference.

8. An electrocardiographic system comprising:

at least one electrode;

at least one wire, each wire connected to an electrode;

the circuit of claim 1 connected to the at least one wire to remove the magnetic resonance interference N(f).

9. The system according to claim 8, wherein each at least one wire is connected to a separate circuit.

10. The system according to claim 8, further including:

at least one patient monitor which receives the physiological signal S(f), with reduced magnetic resonance interference

11. A method for use in an MR system to reduce MR interference of a physiological signal S(f), the method comprising:

inputting a first signal which includes all interference components generated by the MRI scanner N(f) and a physiological signal S(f);

combining subtractively a second signal S(f)+E(f) including the physiological signal S(f) and an error signal E(ft) from the first signal S(f)+N(f), and generating a difference signal N(f)−

E(f),

filtering the difference signal using a high pass filter;

combining subtractively first signal S(f)+N(f) and the filtered signal H(f)*[N(f)−

E(f)] from the high pass filter, and generates the second signal S(f)+E(f).

12. The method according to claim 11, further including filtering the second signal using a low pass filter.

13. The method claim 11, wherein the first signal include a physiological signal,

15. The method according to claim 11, wherein the method is performed on each of a plurality of electrocardiogram (ECG) electrode leads.

16. The method according to claim 11, wherein filtering includes slew rate limiting.

17. A non-transitory computer-readable storage medium carrying software which controls one or more electronic data processing devices to perform the method according to claim 11.

18. An electronic data processing device configured to perform the method according to claim 11.

14. The method according to claim further including:

convening the second signal from an analog wavefouli to a digital waveform.

19. A circuit for use in an magnetic resonance (MR) system to reduce MR interference of a physiological signal S(f), the circuit comprising.:

a lead which carries an input signal including S(f) contaminated with an interference signal N(f);

a feed forward path which feeds forward the interference signal N(f) in a feed forward circuit;

a node which subtractively combines the input signal S(f)+N(f) and the fed forward interference signal N(f) to generate an output signal S(f).

20. The circuit according to claim 19, wherein the output signal includes S(f) and an error component E(f) and further including:

a feedback circuit which feeds back the output signal S(f)+E(f) to the feed forward path to minimize the error component E(f); and

a second node which subtractively combines the fed back output signal S(f)+E(f) and the input signal S(f)+N(f) such that the feed forward signal includes the interference signal and the error signal N(f) and E(f).