Controlled eddy currents: applications to MR imaging

We describe how the artifact caused by eddy currents generated in free standing copper coils may be controlled and used to advantage in magnetic resonance (MR) imaging. The eddy currents distort the excitation field of the MR imager in the vicinity of the coil; the coils may then be used to reduce the signal intensity of tissues adjacent to them. Two examples of how this signal reduction may be used to advantage are given. In one example a coil was used to eliminate an aliasing artifact by removing the signal from an unwanted object. In another example a coil was placed on the anterior abdominal wall of a subject, thereby reducing the high-intensity signal from subcutaneous fat and the resulting ghosting from respiratory motion.