Which Factors Influence MRI In-Stent Lumenvisibility of Coronary In-Stent Stenosis? An In-Vitro Model Investigation

摘要

Purpose: Coronary metal stents generally ham-per lumenvisibility in coronary MR angiography (cMRA); yet, there is considerable scientific interest, clinical need and eco-nomic implication in early detection of in-stent stenosis. There-fore we sought to develop a systematic and standardized ap-proach to evaluate which factors need to be optimized for quantification of in-stent stenosis by analysis of lumenvisibility in a static MRI in-vitro model of coronary in-stent stenosis.Materials and methods: Six different types of stents (all with a diameter of 3.5 mm) were mechanically fixed parallel to the static magnetic field B_0 of the MRI within a static phan-tom. A artificial material, corresponding to smooth muscle cells and neointima, was used to simulate an artificial stenosis 50% and 75% in diameter. The MRI protocol was carried out by usage of different sequences in a 1.5 Tesla system. The prepared stents were filled with NaCl solution. Signal intensi-ties inside and outside the stents were measured.Results: Quantification of in-stent stenosis using MRI was limited in stainless steel stents and cobalt-chromium stents by artifacts. Tantalum stent showed a lower rate of artifacts and measuring the degree of stenosis was possible.Discussion: Whereas MRI is not clinically used for coronary imaging, our specific ex-vivo test procedure indicated a feasi-bility to quantify the degree of in-stent stenosis. Image quality was strongly depended from stent material and stent design. Therefore further research on coronary stents is needed to optimize the MRI protocol and to test the accuracy in a clinical setting.