Coronary magnetic resonance angiography for assessment of the stent lumen: A phantom study

Purpose: To evaluate the feasibility of visualizing the stent lumen using coronary magnetic resonance angiography in vitro. Material and methods: Nineteen different coronary stents were implanted in plastic tubes with an inner diameter of 3 mm. The tubes were positioned in a plastic container filled with gel and included in a closed flow circuit (constant flow 18 cm/sec). The magnetic resonance images were obtained with a dual inversion fast spin-echo sequence. For intraluminal stent imaging, subtraction images were calculated from scans with and without flow. Subsequently, intraluminal signal properties were objectively assessed and compared. Results: As a function of the stent type, various degrees of in-stent signal attenuation were observed. Tantalum stents demonstrated minimal intraluminal signal attenuation. For nitinol stents, the stent lumen could be identified, but the intraluminal signal was markedly reduced. Steel stents resulted in the most pronounced intraluminal signal voids. Conclusions: With the present technique, radiofrequency penetration into the stents is strongly influenced by the stent material. These findings may have important implications for future stent design and stent imaging strategies.