Improvement of the MR imaging behavior of vascular implants

Vascular implants can cause significant MR image artifacts due to the material (susceptibility artifact) or the electromagnetic characteristics (RF artifact). These artifacts are caused by the distortion of the magnetic field and interferences with the radio frequency (RF) waves of the MR imaging process. Void or complete vanishing of signals occurs in close proximity or inside implants. The artifacts can be minimized by using a material with low magnetic susceptibility and a design of the implant which avoids electrical conductive loops. But not all designs can be made loop-free and non conductive. A resonant circuit tuned to the Larmor frequency of the MR tomography overcomes the RF artifact and thus improves the visualization of the implant lumen. The paper reviews the state-of-the-art technology of the MR-signal improvement in implants lumen, with particular regard to the use of resonant circuits such as stents or Vena Cava Filter (VCF), with resonators in 1.0 Tesla and 1.5Tesla MRT.