The present invention provides a coating that emits magnetic resonance signals and a method for coating medical devices therewith. The coating includes a paramagnetic metal ion-containing polymer complex that facilitates diagnostic and therapeutic techniques by readily visualizing medical devices coated with the complex. The present invention also provides methods by which pre-existing polymers and medical devices may be made MR-imageable. The invention also provides methods of improving MR-imageability of polymers and medical devices by encapsulating the polymers and medical devices with hydrogels.