Saeedi Mahrad, Thomas Asish, Shellock Frank G
Loyola Marymount University, 1 LMU Drive, Los Angeles, CA 90045.
Keck School of Medicine, University of Southern California and Institute for Magnetic Resonance Safety, Education, and Research, Playa Del Rey, CA 90293.
Magn Reson Imaging. 2015 May;33(4):497-501. doi: 10.1016/j.mri.2015.01.012. Epub 2015 Jan 22.
Replacement of the aortic heart valve typically requires open-heart surgery. A new transcatheter aortic valve replacement (TAVR) bioprosthesis made from metallic material was recently developed that is an advantageous alternative insofar as it is implanted using a minimally invasive procedure. Because of the presence of metal, there are safety issues related to MRI. Therefore, the purpose of this study was to use standardized testing techniques to evaluate MRI issues for this TAVR bioprosthesis in association with a 3-Tesla MR system.
The TAVR bioprosthesis (Hydra Aortic Valve, Percutaneous Heart Valve Prosthesis, Vascular Innovations Company, Ltd, Thailand) was evaluated for magnetic field interactions (translational attraction and torque), MRI-related heating at a relative high specific absorption rate level (whole body average SAR, 2.9-W/kg), and artifacts (T1-weighted, spin echo, and gradient echo pulse sequences) at 3-Tesla.
The TAVR bioprosthesis demonstrated negligible magnetic field interactions (deflection angle, 3-degrees; torque, 0) and minimal heating (maximum temperature rise, 2.5°C; background temperature rise, 1.7°C). Artifacts were relatively small in relation to the size and shape of the implant.
The TAVR bioprosthesis that was evaluated in this investigation is acceptable, or using current MRI terminology "MR Conditional", for a patient undergoing MRI at 3-Tesla or less.
主动脉心脏瓣膜置换通常需要进行开胸手术。最近研发出一种由金属材料制成的新型经导管主动脉瓣置换术（TAVR）生物假体，由于其采用微创手术植入，是一种有利的替代方案。由于存在金属，与磁共振成像（MRI）相关存在安全问题。因此，本研究的目的是使用标准化测试技术，评估这种TAVR生物假体在3特斯拉MR系统中的MRI相关问题。
对TAVR生物假体（Hydra主动脉瓣，经皮心脏瓣膜假体，泰国血管创新有限公司）进行磁场相互作用（平移吸引力和扭矩）、相对高比吸收率水平（全身平均比吸收率，2.9瓦/千克）下的MRI相关加热以及3特斯拉时的伪影（T1加权、自旋回波和梯度回波脉冲序列）评估。
TAVR生物假体显示出可忽略不计的磁场相互作用（偏转角，3度；扭矩，0）和最小加热（最大温度升高，2.5°C；背景温度升高，1.7°C）。相对于植入物的大小和形状，伪影相对较小。
本研究中评估的TAVR生物假体对于在3特斯拉及以下接受MRI检查的患者是可接受的，或者用当前MRI术语来说是“MR条件适用”的。
