Abstract: A leadwire harness system is used for recording an electrocardiogram (ECG) during magnetic resonance imaging (MRI). The system includes a set of leadwires each having a nichrome wire helically wound on a bundle of glass or other high strength fibers and surrounded by an insulating jacket to provide for uniformly distributing the high resistance within each leadwire so that the eddy currents generated by the rapidly changing magnetic field are greatly reduced. The set of leadwires are twisted within a surrounding tube of foam insulation. The reduction of the eddy currents dramatically reduces MRI image distortion as well as the potential for localized heating and skin burns under the ECG electrodes used with the harness system.
Abstract: An elongated flexible lead conducts electrical biosignals from a medical electrode attached to a person's skin to a recording instrument and the lead is translucent to X-rays. The lead includes a primary center conductor formed by a bundle of conductive fibers such as carbon fibers, and a tubular layer of electrical insulating plastic material surrounds the fibers. An electrical conducting non-metallic shielding member extends around the tubular layer, and in one embodiment includes a bundle of the carbon fibers surrounded by a tubular layer of electrical conductive plastic material. A tubular layer of electrical insulating plastics material surrounds the shielding member, and the shielding member has an effective low electrical resistance close to that of the primary center conductor.