口腔固定修复金属材料磁共振伪影的对比研究

Comparative study of MRI artifacts from metal materials of dental fixed prothesis

目的:比较口腔临床常用的固定修复金属材料在磁共振成像(magnetic resonance imaging,MRI)检查中伪影的大小。方法:选取拟作全冠或桩核冠的志愿者各1名,分别制作5种金属全冠(钴铬合金、镍铬合金、含钛合金、纯钛、金合金)和4种金属桩核(钴铬合金、镍铬合金、含钛合金、纯钛)。将修复体依次就位于基牙,进行1. 5T磁共振T1加权梯度回波序列扫描,测量MRI图像上伪影的最大面积并确定伪影涉及图像的层数。结果:金属全冠中,钴铬合金全冠的伪影最大面积最大(P<0. 001),金合金全冠最小(P<0. 05),镍铬合金全冠大于纯钛全冠(P<0. 01)和含钛合金全冠(P<0. 05),含钛合金全冠与纯钛全冠之间无显著性差异(P>0. 05);钴铬合金全冠伪影涉及的层数最多,金合金全冠最少,其余全冠相等。金属桩核中,钴铬合金桩核的伪影最大面积最大(P<0. 001),纯钛桩核最小(P<0. 05),镍铬合金桩核大于含钛合金桩核(P<0. 001);钴铬合金桩核伪影涉及的层数最多,其余金属桩核相等。伪影波及的解剖结构影像主要局限于正中矢状面同侧颌面部,颅脑部和颈椎部图像未受影响。结论:口腔固定修复金属材料产生的伪影大小与材料类型密切相关,钴铬合金产生的伪影最大,金合金产生的伪影最小;单个金属全冠、桩核产生的伪影不会影响颅脑部和颈椎部的图像;除钴铬合金桩核外,磨牙区单个金属全冠、桩核产生的伪影不会影响正中矢状面对侧解剖结构的影像。

Objective: To compare the artifacts generated by dental metal materials of fixed prothesis in magnetic resonance imaging(MRI). Methods: Two volunteers who need full crown or post-and-core crown restoration were recruited. Full crowns were fabricated with five different materials(Co-Cr alloy, Ni-Cr alloy, pure Ti, Ti alloy and Au alloy), post-and-cores with four materials(Co-Cr alloy, Ni-Cr alloy, Ti alloy and pure Ti). The samples were seated on teeth and MRI scan(1.5 T)with T1 weighted gradient recalled echo(GRE) pulse sequence was performed. The maximum area and the number of sections of artifacts were acquired. Results: Among the metal crowns, the maximum area of artifact of Co-Cr alloy was the largest(P<0.001), and the one of Au alloy was the smallest(P<0.05), and the one of Ni-Cr alloy was larger than those of Pure Ti(P<0.01) and Ti alloy(P<0.05). No significant difference was found between Pure Ti and Ti alloy(P>0.05). Artifact of the Co-Cr alloy crown affected the most slices, and the one of Au alloy affected the least, and the ones from the other three crowns affected the same number. Among the metal post-and-cores, the maximum area of artifact of Co-Cr alloy was the largest(P<0.001), and the one of pure Ti was the smallest(P<0.05), and the one of Ni-Cr alloy was larger than that of Ti alloy(P<0.001). Artifact of the Co-Cr alloy post-and-core affected the most slices, and artifacts from the others affected the same number. The images of anatomical structures affected by artifacts were mainly limited to the ipsilateral maxillofacial region, and the images of craniocerebral region and cervical spine were unaffected. Conclusion: The area of artifacts generated by metal materials of dental fixed prothesis is closely related to the type of material. The artifact from Co-Cr alloy is the largest, and the one from Au alloy is the smallest. The artifact from a single metal crown or post-and-core would not affect the images of craniocerebral region and cervical spine. With the exception of Co-Cr alloy post-and-core, the artifact from a single metal crown or post-and-core in the molar area does not affect the images of contralateral anatomical structures.