金合金、镍络合金铸造冠对磁共振成像检查的影响

Effects of gold alloy,Ni-Cr alloy casting crown on MRI examination

目的 :研究金合金与镍铬合金铸造冠对磁共振检查准确性的影响。方法 :取猴右侧上颌侧切牙分别制作、配戴金合金、镍铬合金铸造冠 ,用 2 .0TPrestigeMR扫描仪按临床常规进行 5个常用序列 (T1:自旋回波T1加权像 ;T2 :快速自旋回波T2加权像 ;PD :快速自旋回波质子密度像 ;GRE :梯度回波T1加权像 ;GEEPI :单次激发平面回波成像 )的头颈部扫描 ,观察铸造冠对图像的影响。结果 :金合金冠无明显伪影形成 ;镍铬合金冠周围组织的影像在T1、T2、PD、GRE畸变为近似圆形的低信号伪影 ,在GEEPI畸变为不规则的片状信号失落 ;GRE影像畸变 (伪影 )涉及 6个扫描层面 ,最大直径约 19mm。结论 :金合金修复体不影响MRI检查的准确性 ;镍铬合金修复体使其毗邻组织的磁共振成像发生畸变 ,累及范围和影响程度因扫描序列而异。

AIM:To compare the effects between Gold alloy casting crown and Ni-Cr alloy crown on MRI.METHODS: A casting Gold alloy crown and a Ni-Cr alloy crown were put on a narcotized monkey's right upper lateral incisor respectively. Then the monkey′s head and neck was examined with a 2.0 T MRI scanner. Four clinical routine scanning sequences including spin echo (T1), fast spin echo (T2), proton density (PD),gradient echo (GRE) and one functional scan protocol (gradient echo planar image, GE EPI) were used to observe the effects of the Gold alloy crown and the Ni-Cr alloy crown. RESULTS:The Gold alloy casting crown created no artifact on all the 5 scans.Metal artifact around the Ni-Cr alloy crown was found on all images with different size and shape. On the T1, T2, PD, GRE images, the artifacts were circular. On the GE EPI images which was patch-shaped. On GRE images, artifact was found in 6 slices, and maximal artifact was approximately 19mm in diameter. CONCLUSION: Gold alloy restorer doesn′t affect the veracity of MRI examination.Ni-Cr alloy restorer results in distortion on all MR images. The distortion was different according to the scan sequence.