Controlled impedance monitoring lead wires
AssigneeGeneral Electric Company
InventorsRandall H. Buchwald, Robert S. Stormont, Jeffrey P. Noonan
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Abstract
An electrode assembly, particularly useful in nuclear magnetic resonance apparatus, for sensing a physical characteristic of a live study subject includes an electrode positioned in electrical contact with the subject for sensing the physical characteristic. The electrode assembly further includes a lead wire connected at one of its ends to the electrode and having an impedance selected to protect the study subject from heating. The impedance is also selected to have a low voltage coefficient of resistivity in order to prevent conversion of radio-frequency energy to ECG in-band energy.
Claims9
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising:
- conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device;
- resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface;
- and
- said resistor means having a voltage coefficient of resistivity selected to provide the conductor means with a linear transfer characteristic.
An improved lead wire assembly for coupling an electrode on a subject in an NMR study to a device for monitoring an electrical signal picked up from said subject by said electrode across an electrode/subject interface having a specified impedance, said subject and said assembly proximate to a radio frequency magnetic field generated in the course of the NMR study, said assembly comprising:
- conductor means for establishing an electrically conductive path for the electrical signal between the electrode and the monitoring device;
- resistor means included in the conductive path for providing the conductive path with an impedance exceeding the specified impedance of the electrode/subject interface;
- and
- said resistor means having a voltage coefficient of resistivity which is of a selected low value sufficient to prevent the conductor means from converting a portion of the energy of the radio frequency magnetic field into an interfering signal having a frequency lying in the frequency range of the electrical signal.
Dependencies are inferred from the claim text.