Radiology Department, Federation of National Public Service Personnel Mutual Aid Associations Shinbeppu Hospital.
Magn Reson Med Sci. 2021 Sep 1;20(3):303-311. doi: 10.2463/mrms.mp.2019-0083. Epub 2020 Sep 18.
In this study, we investigated the factors of signal loss out because of the presence of a stent and optimized imaging parameters for improvement in depiction ability.
We investigated the relationship between the stent type and magnetic susceptibility effect by measuring the signal value between the inside and outside of the stent with different Bw and TE for two different kinds of stents respectively. Similarly, flip angles were changed for two different kinds of stents respectively to the signal intensity between the inside and the outside of the stent was measured, in which examine the relationship between the stent type and the Ernst angles in RF-shielding effect. The conventional imaging parameters and the optimum imaging parameters for each stent obtained from the result of the phantom experiment were examined. Optimized 3D time-of-flight MR angiography (3D-TOF-MRA) was performed and compared with conventional 3D-TOF-MRA and computed tomography angiography (CTA).
The influence of the magnetic susceptibility effect is small in the central part of Carotid Wallstent and in PRECISE, and large in the Carotid Wallstent at the both ends. The influence of RF-shielding effect was large at PRECISE, where the Ernst angle was greatly shifted while the effect is no longer influenced at Carotid Wallstent. Both Carotid Wallstent and PRECISE made imaging capability improved by optimizing the imaging parameters.
During clinical imaging of patients post-carotid artery stenting (CAS) using our protocol, the ability to visualize blood vessels was improved. Thus, we demonstrated that the ability of 3D-TOF-MRA post-CAS was improved via optimizing imaging parameters.
本研究旨在探讨因支架存在而导致信号丢失的因素，并优化成像参数以提高描绘能力。
我们分别测量了两种不同支架的内部和外部之间的信号值，以研究支架类型和磁化率效应之间的关系，同时分别改变两种不同支架的翻转角，以测量支架内部和外部之间的信号强度，从而研究支架类型和 RF 屏蔽效应中的 Ernst 角之间的关系。我们检查了从体模实验结果获得的每个支架的常规成像参数和最佳成像参数。对优化的 3D 时间飞跃磁共振血管造影（3D-TOF-MRA）进行了检查，并与常规 3D-TOF-MRA 和计算机断层血管造影（CTA）进行了比较。
在颈动脉 Wallstent 和 PRECISE 的中心部分，磁化率效应的影响较小，而在颈动脉 Wallstent 的两端影响较大。在 PRECISE 中，RF 屏蔽效应的影响较大，其中 Ernst 角发生了很大的偏移，而在颈动脉 Wallstent 中则不再受到影响。通过优化成像参数，颈动脉 Wallstent 和 PRECISE 都提高了成像能力。
在使用我们的方案对颈动脉支架置入术后患者进行临床成像时，血管可视化能力得到了提高。因此，我们证明了通过优化成像参数可以提高 3D-TOF-MRA 术后颈动脉支架置入术的能力。
