<p>A medical device (10400) comprised of a coating (10402) that inhibits distortion of medical resonance images taken of the device (10400). When the device (10400) is exposed to radio frequency electromagnetic radiation with a frequency of from 10 megahertz to about 200 megahertz, at least 90 percent of such radio frequency electromagnetic radiation penetrates to the lumen of the device (10400); and the concentration of the radio frequency electromagnetic radiation that penetrates to the lumen of the device (10400) is substantially identical at different points within such interior. The coating (10402) is comprised of magnetic material with an average particle size of less than about 40 nanometers.</p>
