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目的探讨人体植入国产室间隔缺损封堵器后接受磁共振检查的安全性,以及植入的金属材料对磁共振成像(MRI)的影响程度。方法采用西门子MagnetomImpact-1·0T磁共振机,选用SE和梯度回波(GE)扫描序列,将镍钛合金丝制成的封堵器分别进行MRI磁场内悬挂试验、水模测试扫描、植入中华小型猪体内后心脏扫描等试验;并且对MR检查前后封堵器的磁导率(μ1·5T)以及原子组成等金属特性进行材料学分析测试,观察其有无变化。结果悬挂的封堵器在不同的磁场方向下无明显移位发生。水模测试扫描显示SE序列封堵器水模图像清晰,信号均匀一致,无伪迹干扰,GE序列图像示轻度伪迹干扰,信号尚均匀。植入封堵器后猪心的短轴及长轴面MR成像显示心脏结构观察清楚,SE序列室间隔部位可见轻度金属伪影,GE序列该金属伪影有所放大。MR检查前后封堵器的磁导率(μ1·5T)以及原子组成等金属特性无明显变化。结论这种国产室间隔缺损封堵器属非铁磁性材料,植入人体后行MR检查是安全的,但其产生的金属伪影可部分影响MR图像的观察,通过选择合适的扫描序列和参数可以减轻封堵器伪影的影响。
Objective To investigate the safety of human MRI after implantation of a domestic ventricular septal defect occluder and the influence of implanted metal materials on magnetic resonance imaging (MRI). METHODS: Magnetic resonance tomography was performed on a Siemens MagneticomImpact-1·0T magnetic resonance machine using SE and gradient echo (GE) scan sequences. The occluder made of NiTi wire was subjected to MRI magnetic field internal suspension test, water mode test scan, and implantation respectively. In vivo and postoperative cardiac scans of Chinese miniature pigs were performed; material properties such as magnetic permeability (μ1·5T) and atomic composition of the occluder before and after MR examination were analyzed and tested for material changes. As a result, no apparent displacement of the suspended occluder occurs in different magnetic field directions. The water model test scan showed that the water images of the SE sequence occluder were clear, the signal was uniform, there was no artifact interference, and the GE sequence images showed mild artifacts and the signal was even. After the occlusion device was implanted, MR imaging of the short axis and long axis of the pig’s heart showed clear observation of the heart structure. Mild metal artifacts were seen in the SE septum and the metal artifacts of the GE sequence were amplified. There was no significant change in the magnetic properties (μ1·5T) and the atomic composition of the occluder before and after the MR examination. Conclusion The domestic ventricular septal defect occluder is a non-ferromagnetic material. MR examination is safe after implantation in the human body. However, the metal artifacts generated may affect the observation of MR images, by selecting appropriate scanning sequences and parameters. Can reduce the effect of occluder artifacts.