Edwards Maria-Benedicta, Ordidge Roger J, Hand Jeffrey W, Taylor Kenneth M, Young Ian R
United Kingdom Heart Valve Registry, Department of Cardiothoracic Surgery, Hammersmith Hospital, Du Cane Road, London W12 0NN, United Kingdom.
J Magn Reson Imaging. 2005 Aug;22(2):311-7. doi: 10.1002/jmri.20373.
To assess the magnetic field interactions on 11 heart valve prostheses and 12 annuloplasty rings subjected to a 4.7 T MR system.
Ex vivo testing was performed to evaluate translational and rotational forces using previously described techniques.
Seventeen out of 23 prostheses showed zero interaction with the magnetic field. Translational forces with deflection angles of 2-20 degrees were demonstrated in six prostheses. Only two heart valves and two annuloplasty rings demonstrated rotational forces. The Carpentier Edwards (CE) Physio Ring, which contains Elgiloy, demonstrated deflection angles three times greater than those previously measured at 1.5 T. Furthermore, there was a direct relationship between increasing prosthesis size and increasing translational force. All heart valve prostheses attracted to the magnetic field were slightly paramagnetic/weakly ferromagnetic.
Twenty-three heart valve prostheses evaluated for MRI are considered safe in static fields up to 4.7 T based on current safety criteria. However, the CE Physio Ring appeared to develop an increasing magnetism upon re-entry into the MR system. We conclude that prostheses made from Elgiloy may not be acceptable for patients in an MR environment of > or =4.7 T. Further investigations are required to confirm the safety of Elgiloy.
评估11个心脏瓣膜假体和12个瓣环成形环在4.7 T磁共振（MR）系统中的磁场相互作用。
采用先前描述的技术进行离体测试，以评估平移力和旋转力。
23个假体中有17个与磁场的相互作用为零。6个假体表现出偏转角为2 - 20度的平移力。只有两个心脏瓣膜和两个瓣环成形环表现出旋转力。含有埃尔吉洛伊耐蚀合金的卡彭蒂埃·爱德华兹（CE）生理环的偏转角比先前在1.5 T时测量的大两倍。此外，假体尺寸增大与平移力增加之间存在直接关系。所有被磁场吸引的心脏瓣膜假体均呈轻微顺磁性/弱铁磁性。
根据当前安全标准，对23个用于磁共振成像评估的心脏瓣膜假体而言，在高达4.7 T的静磁场中被认为是安全的。然而，CE生理环在再次进入MR系统时似乎会产生越来越强的磁性。我们得出结论，由埃尔吉洛伊耐蚀合金制成的假体对于处于≥4.7 T磁共振环境中的患者可能是不可接受的。需要进一步研究以确认埃尔吉洛伊耐蚀合金的安全性。
