Placement of an inferior vena cava filter in a pig guided by high-resolution MR fluoroscopy at 1.5 T

Percutaneous placement of an inferior vena cava filter is a means for long-term prevention of pulmonary thromboembolism. In this study we investigated the magnetic resonance (MR) imaging properties of a Nitinol vena cava filter, in various anatomic and angiographic scans, as well as the feasibility of placing this filter under near real-time, high-resolution MR fluoroscopy. We made use of the passive tracking strategy, with on-line image processing and visualization, both in vitro and in a pig. The artifacts provoked by the metallic filter were such that the position and orientation of the filter were well depicted in all scans. Considerable radiofrequency caging obscured the interior of the filter. Our experiments showed that an MR-guided vena cava filter placement, with sufficient temporal and spatial resolution, is possible. Three-dimensional phase contrast MRA allowed direct evaluation of the filter placement procedure, without the use of contrast agent.