Straube T, Wolf S, Flesser A, Deli M, Alfke K, Nabavi A, Jansen O
Sektion Neuroradiologie der Klinik für Neurochirurgie, Christian Albrechts Universität Kiel.
Rofo. 2005 Mar;177(3):375-80. doi: 10.1055/s-2004-813878.
To evaluate MR artifacts of carotid artery stents and to optimize stent properties and sequence parameters.
Four carotid artery stents - Wallstent (mediloy), Precise (nitinol), ACCULINK (nitinol) and a stent prototype (nitinol) - were investigated in a flow model of the cervical vessels. The model was made of silicon tubing and a flow pump that produces realistic flow curves of the carotid artery. To investigate the effects of magnetic susceptibility and radiofrequency induced shielding artifacts, turbo spin echo and gradient echo sequences as well as CE-MRAs were measured. To improve the visualization of the stent lumen in a CE-MRA, flip angle as well as geometry and covering of the stent prototype were altered.
Susceptibility artifacts in stents of the carotid artery only influence the lumen visualization at the proximal and distal end of the braided mediloy stent. A change of stent coverings has no significant influence on radiofrequency artifacts, whereas a reduction in linking elements between stent segments and a change in diameter of stent struts improves visualization of the stent lumen. By increasing the flip angle in a CE-MRA, visualization of the stent lumen is possible in both mediloy and nitinol stents.
The choice of stent material and changes in stent geometry as well as the optimization of the flip angle of the CE-MRA may reduce susceptibility and radiofrequency artifacts, rendering feasible the CE-MRA of a stented carotid artery.
评估颈动脉支架的磁共振伪影，并优化支架特性和序列参数。
在颈部血管血流模型中研究了四种颈动脉支架——Wallstent（医用洛伊合金）、Precise（镍钛合金）、ACCULINK（镍钛合金）和一种支架原型（镍钛合金）。该模型由硅胶管和一台能产生逼真颈动脉血流曲线的血流泵组成。为研究磁敏感性和射频感应屏蔽伪影的影响，测量了快速自旋回波序列、梯度回波序列以及对比增强磁共振血管造影（CE-MRA）。为改善CE-MRA中支架管腔的可视化效果，改变了支架原型的翻转角以及几何形状和覆盖情况。
颈动脉支架中的磁敏感性伪影仅影响编织医用洛伊合金支架近端和远端的管腔可视化。支架覆盖层的改变对射频伪影无显著影响，而减少支架节段之间的连接元件以及改变支架支柱直径可改善支架管腔的可视化。通过增加CE-MRA中的翻转角，医用洛伊合金和镍钛合金支架的管腔均可实现可视化。
选择支架材料、改变支架几何形状以及优化CE-MRA的翻转角可减少磁敏感性和射频伪影，使置入支架的颈动脉的CE-MRA成为可能。
