非贵金属桩核冠伪影对颅脑和颈椎MRI图像的影响

Influence of Ni-Cr alloy post-core crown artifacts on cranial brain and cervical vertebra MRI

目的探讨颅脑及颈椎MRI成像时不同牙位钴铬合金、镍铬合金桩核冠MRI图像伪影累及的具体解剖结构,以更好地指导临床对材料的选取。方法选择钴铬合金(Co 60.2%,Cr 25%,W 6.2%,Mo 4.8%,Ga 2.9%,Si,Mn)、镍铬合金(Ni 60%~64%,Cr 21%~25%,Mo 10%~12%),制成右上及左上1、6标准桩核冠模型。选择口腔卫生良好,口腔内恒牙列完整、咬合正常、无充填体及修复体、无龋齿、无牙列拥挤、无颈椎及颅脑疾病的成年健康志愿者20例,其中女性10例,男性10例;年龄31~62岁,平均年龄47.85岁;体质量45~80 kg;身高155~181 cm。将不同牙位的钴铬合金、镍铬合金桩核冠分别咬于志愿者相应牙位的上下牙之间,行颅脑横断面及矢状面T_2加权成像(T_2WI)、颅脑横断面弥散加权成像(DWI)、颈椎矢状面T_2WI,观察伪影对周围解剖结构的影响。结果所有志愿者不同牙位钴铬合金及镍铬合金头部横断面T_2WI、DWI各个层面图像均未出现金属伪影。在矢状面T_2WI图像上,只在近桩核冠修复体周围(舌体前部、颌骨)出现了伪影,但是金属伪影均达不到颅脑组织内,不影响对颅脑组织的观察。所有志愿者不同牙位钴铬合金及镍铬合金颈椎矢状面T2WI图像伪影只是单纯影响了桩核冠修复体局部,伪影范围达不到椎体、脊髓。结论单个钴铬合金或镍铬合金桩核冠不会对颅脑和颈椎图像产生影响。

Objective To study the specific anatomical structure of different dental position with Co-Cr alloy and Ni-Cr alloy metal artifacts on cranial brain and cervical vertebra MRI, and provide guidance for clinical material selection. Methods The Co-Cr alloy（Co 60.2 %, Cr 25 %, W 6.2 %, Mo 4.8 %, Ga 2.9 %, Si, Mn） were molded into right standard post-core crown model, Ni-Cr alloy（Ni 60 %-64 %,Cr 21 %-25 %, Mo 10 %-12 %） were molded into left standard post-core crown model. Twenty healthy adult volunteers（included 10 females and 10 males, aged 31-62 years old with mean age of 47.85 years old; body weight of 45-80 kg; height of 155-181 cm） with good oral hygiene, complete permanent dentition in oral cavity and normal occlusion, without filling and restorations, dental caries, crowding and dentition, cervical and cranial diseases were enrolled in the study. The post-core crown model was bitten between corresponding dental position at upper and lower tooth.The cranial axial and sagittal T_2-weighted imaging（T_2WI）, cranial axial diffusion weighted imaging（DWI） and cervical sagittal T_2WI were conducted. The influence of artifacts on anatomy structure was observed. Results There was no metal artifacts were observed in all images of axial brain T_2WI and DWI images of Ni-Cr alloy and Co-Cr alloy. In sagittal T_2WI image, only artifacts appeared around the post-core crown restoration（the front of tongue and jaw）, while metal artifact was not reached brain tissue and affected the observation of brain tissue. In all subjects, the T_2WI image artifacts of Ni-Cr alloy and Co-Cr alloy on cervical sagittal simply affected the local part of post-core crown restoration, and the artifact did not reach vertebral body and spinal cord. Conclusion It is demonstrated that single post-core crown artifacts will not affect the diagnosis of brain and cervical vertebra.