口腔金属材料对头部磁共振成像影响程度的探讨

A preliminary study of the ghost with metal materials on MR imaging

目的 检测口腔临床常用的金属材料对磁共振成像影响程度。方法 将银汞合金、钴铬合金、镍铬合金和纯钛等口腔常用金属材料模块 ,放在磁共振测试用水模上 ,用GE - 1.5T超导磁共振机进行扫描。选用不锈钢固定桥和镍铬合金烤瓷桥 ,以金属固定桥为中心 ,测定其冠状位和矢状位上的最大影响范围。结果 金、银、钛、银汞合金和镍钛记忆合金对磁共振成像无影响 ;不锈钢全冠、医用不锈钢丝、钴铬合金和镍铬合金对磁共振成像有不同程度的伪迹干扰 ,尤以镍铬合金的干扰最为严重。不锈钢全冠固定桥和镍铬合金烤瓷桥致磁共振图像扭曲、变形和缺损 ,干扰信号区域呈椭圆形 ,与固定桥长轴一致 ,其最大影响范围约为固定桥近远中径的 2倍 ,颊舌径的 4倍。结论 金、银、银汞合金、钛和镍钛记忆合金因其导磁率低而对磁共振成像无干扰。不锈钢全冠、医用不锈钢丝、钴铬合金和镍铬合金对磁共振成像均有不同程度的影响 ,以镍铬合金对MR影像的干扰最为严重。

Objective To detect the influential degree in magnetic resonance imaging caused by metal mateial used in stomatological clinics.Methods Put the metal material template that was commonly used in stomatological clinics such as dental amalgam,cobuvt-chromium alloy,nichrome and titanium on MRI test water-membrance.Then MR imaging was obtained.Results Gold,silver,titanium,dental amalgam and nickel-titaniaum alloy had no influnce on MR imaging,but stainless steel complete crown,medical stainless steel,cobult-chromium and nichrome had different degree artificial interference on MRI,especially nichrome.Stainless steel complete crown fixed bridge and nichrome procelian caused the imaging of distortion,deformatione and defect.The region of the interference signal was oval and consistent with long axial of fixed bridge.The largest influential range was approximately double times of fixed bridge's mesiodistal diameter and four times of buccolingual diameter.Conclusion The metals commonly used in present stomatological clinics,such as gold,silver,dental amalgam,titanium and nickel-titanium alloy do not cause interference in MRI because of their low magnetic conductivity.There is no need to remove these metals before MR examination.The stainless steel complete crown, medical stainless steel wire, cobult-chromium alloy and nichrome affect MR imaging,removal of which night be considered based on given conditions.