口腔内金属材料和磁共振检查伪影

Metallic Dental Materials and MR Artifacts

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。材料与方法：对２２种２５件口腔内常用金属材料做了磁共振成像测试，磁共振仪磁场强度为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１１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、椿钉等１２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。

Objective: To evaluate the existence and extent of MR artifacts caused by frequently used metallic dental materials and to compare the influence of different MRI sequences on artifacts.Materials and Methods:A total of 22 kinds and 25 metallic dental samples were tested with 1.5 T MR scanner using gradient echo sequence. Spin echo and fast spin echo were also performed for some of these samples.Results:Of all the 25 metallic dental samples, 11 ones containing gold, amalgam, silver point, etc. did not produce any artifact. Titanium alloy and porcelain product fused in metal yielded some artifacts in a mild degree. Whereas the remaining 12 samples, such as the retention pin and pivot pin, showed obvious artifacts. Artifacts produced by retention pin, nickel chromium crown and such like were less obvious on fast spin echo.Conclusion: When face, jaw or head were studied with MR, attention should be paid to some certain metallic dental materials, as they might produce obvious MR artifacts and, thus, deteriorate the image quality. Artifacts can be avoided or reduced by using proper metallic materials or choosing proper scan sequence and parameters.