金属节育器在常规医用磁共振检查时的受力检测

Force Testing of Metal IUD in Conventional Medical MRI

目的通过建立实验模型,测试宫内节育器(IUD)与常规医用磁共振(MR)的相互影响,以期确定使用IUD的对象能否进行MRI检查。方法将磁性与非磁性纯铜IUD,分别放置于测试模型上,在0.4 T、1.0 T、1.5 T、3.0 T MR机上测试IUD各点的平移力和扭力。结果磁性金属IUD在0.4 T永磁MR圈内中心磁力最强,平移力最强,力的方向指向圈内中心,与机器是否扫描无关,未能测到扭力。在1.0 T、1.5 T、3.0 T超导型MR外圈平移力明显,近圈缘最高,未测到扭力,圈内保持磁性平衡,合力为零,平移力与扭力为零。非磁性金属铜IUD不存在平移力和扭力。以上数据与机器是否扫描无关。结论金属磁性IUD的位置变化是在进入检查室及进入检查腔的过程中产生,并不是在扫描中产生,在扫描中并无扭力产生;非磁性纯铜IUD在常规医用MR测试无平移力和扭力,检查时不存在受磁力牵拉引起的移位、出血。

Objective To establish experimental model to test the interaction of intrauterine device （ IUD） with conventional med-ical magnetic resonance （ MR） , so as to determine whether the patients using IUD could be checked by MRI or not. Methods Mag-netic IUD and non-magnetic copper IUD were placed on the test model respectively. The translational force and torque of various IUD points were tested on 0. 4T, 1. 0T, 1. 5T and 3. 0T MR machine. Results In the 0. 4 T magnetic metal circle center, magnetic metal IUD showed the strongest magnetic force and translational force. The direction of the force pointed to the circle center and had nothing to do with machine scanning;torque was not tested. Superconductive MR outer translational force was obvious on 1. 0 T, 1. 5 T, 3. 0 MR machines with the highest recent lap margin, torque was not tested, magnetic circle maintained magnetic balance, the forces were zero, translational force and torque were zero. Non-magnetic metal copper IUD didn＇t have translational and torsional forces. The data above had nothing to do with machine scanning. Conclusion The change of the position of magnetic metal IUD happens in the process of entering into the examination room and cavity instead of scanning;while there is no torque in the process of scanning. Non-magnetic copper IUD didn＇t have translational force and torque tested by conventional medical magnetic resonance （MR）, without shifting and bleeding caused by magnetic pulling during testing.