口腔非贵金属修复体磁共振成像伪影影响因素分析

An Analysis of Influential Factors on MRI Artifacts of Oral Non-precious Metal Prosthesis

目的:探讨MR成像时不同因素对口腔内非贵金属修复体伪影大小的影响。方法:选用钴铬合金和镍铬合金分别制成左上1(前牙)、左上6(后牙)标准桩核冠模型做为实验组,用丙烯酸树脂制成大小形状相同的模型做为对照组,将模型固定于水模中。应用1.5T MR扫描仪,头线圈,对实验组及对照组桩核冠行磁共振扫描,扫描策略如下:1)选取钴铬合金、镍铬合金、树脂后牙,分别行横断面T1WI、T2WI、T2*WI、FLAIR、DWI成像。2)选取钴铬合金、镍铬合金后牙,分别行横断面、矢状面、冠状面T1WI及T2WI成像。3)选取镍铬合金前牙及后牙,分别行横断面、矢状面、冠状面T2WI成像。确定伪影最大的层面并测量伪影面积。应用SAS V8统计学软件进行数据分析,以P<0.05为差异有统计学意义。结果:3种材料在磁共振图像上伪影由大到小依次为:镍铬合金、钴铬合金、树脂对照(P<0.01)。不同序列金属伪影大小不同,DWI最大,T2*WI次之,然后是T2WI,T1WI与FLAIR序列伪影最小(P<0.01)。不同扫描层面金属伪影大小不同(P<0.05)。后牙比前牙金属伪影大(P<0.01)。结论:在非贵金属范围内选择修复体材料时可以选择生物相容性较好磁共振伪影又较小的钴铬合金。

Objective：To investigate influential factors on MRI artifacts of oral non-precious metal prosthesis.Methods：Two kinds of non-precious metal dental materials（Ni-Cr alloy and Co-Cr alloy）were molded into standard post-core-crown models as experimental group.Acrylic resin post-core-crown with the same size and shape was used as control group.The models were fixed in a water phantom.The Ni-Cr alloy,Co-Cr alloy and acrylic resin post-core-crown models were scanned by 1.5T MR scanner with the head coil.Scanning strategy was as follows：1）Ni-Cr alloy,Co-Cr alloy and resin posterior teeth were selected,and axial T1 WI,T2WI,T2＊WI,FLAIR,DWI sequences were scanned respectively.2）Ni-Cr alloy and Co-Cr alloy posterior teeth were selected,and axial,sagittal,and coronal T1 WI,T2WI sequences were scanned respectively.3）Ni-Cr alloy anterior tooth and posterior teeth were selected,and axial,sagittal,and coronal T2 WI sequences were scanned respectively.The section with the greatest artifact was determined and the area was measured.Statistical testing was performed.Results：The sizes of the artifacts in descending order were as follows：Ni-Cr alloy,Co-Cr alloy and acrylic resin post-core-crown（P〈0.01）.The sizes of the artifacts were different at different sequences,and in descending order were DWI,T2＊ WI,T2 WI,T1WI and FLAIR（P〈0.01）.The sizes of the artifacts were different at different sections（P〈0.01）.The artifacts of the posterior teeth were greater than those of the anterior teeth（P〈0.01）.Conclusion：It is feasible to choose Co-Cr alloy in non-precious metal for its better biocompatibility and less artifacts.