Magnetic resonance (MR) guided endovascular intervention is an attractive guiding technique, but until now it has been difficult to visualize the catheter. Here it is revealed that by chemically attaching a Gd complex to the polyethylene surface of the catheter strong MR signals and a clear contrast between the coated materials and the background can be obtained. The Figure shows one uncoated (d) and three coated (a,b, c) samples. [GRAPHICS]