口腔用金属材料的磁共振伪影的检测

Primary Observation by Measuring Magnetic Resonance Artifacts Caused by Metallic Dental Materials

目的 检测口腔内常用金属材料在磁共振检查时是否产生伪影和伪影的严重程度 ;并比较不同检查序列对伪影的影响。方法 对 2 2种 2 5件口腔内常用金属材料做了磁共振成像测试 ,磁共振仪磁感应强度为 1 .5T ,所用序列是梯度回波 ,部分材料加做自旋回波和快速自旋回波。结果 铸金片、银汞合金、银尖等 1 1件试样无伪影 ;钛合金和金属烤瓷成品有轻度伪影 ;牙用固位钉、椿钉 1 2件试样有严重伪影。牙用固位钉、镍铬合金冠等材料在快速自旋回波图像上伪影减轻。结论 部分口腔内金属材料会引起严重伪影 ,影响图像质量 ,所以在做口腔颌面部和脑部磁共振成像时 ,须引起重视。通过合理选择金属材料 。

Purpose: To evaluate the existence and extent of magnetic resonance(MR) artifacts caused by frequently used metallic dental materials and to compare the influence of different MRI sequences on artifacts. Methods: A total of 22 kinds and 25 metallic dental samples were tested with 1.5 T MR imager and gradient-echo sequence. Spin-echo and fast spin-echo were added to parts of these samples. Results: Of all the 25 metallic dental samples, 11 including gold, amalgam, and silver point did not produce artifact. Titanium alloy and porcelain product fused in metal had mild artifacts. Whereas the remaining 12 samples such as the retention pin and pivot pin showed severe artifacts. Artifacts produced by retention pin, nickel-chromium crown and so on were less severe on fast spin-echo. Conclusions: Attention should be paid to some of the metallic dental materials, which could cause severe MR artifacts and image degradation, when undergoing face, jaw and head MR examination. Artifacts can be alleviated by using proper metallic materials or choosing proper imaging sequence and parameters.