软、硬质钴铬合金及金合金对磁共振成像伪影的影响

Effects of soft,hard cobalt-chromium casting alloy and gold alloy on magnetic resonance imaging artifacts

背景:磁共振成像具有高对比度、无骨伪影、任意方位断层等优点,被广泛应用于头颈外科、神经外科和口腔颌面外科疾病的诊断。但某些金属材料在磁共振成像中形成的伪影严重影响了图像质量,这些材料的使用限制了磁共振成像在头颈部的应用和准确诊断。目的:观察硬质钴铬铸造合金、软质钴铬铸造合金、金合金3种金属材料在5种不同头颈部扫描序列中的伪影。方法:采用5种头颈常规及快速成像序列,分别对放置于圆柱型水模中心的3种金属试样进行轴位扫描,测量伪影,并进行统计分析。结果与结论:3种金属在磁共振成像相同成像序列中,金合金产生的伪影最小,硬质钴铬形成的伪影最大,各组间比较差异有显著性意义(P均<0.05);相同金属材料,自旋回波序列产生伪影最小,梯度回波序列产生伪影较大,平面回波序列产生伪影最大并使图像变形。结果提示,与非贵金属口腔修复材料相比,以贵金属作为口腔修复材料,在头颈部磁共振成像过程中产生的伪影最小,因此通过合理选择口腔金属修复材料及成像技术,可得到最佳磁共振成像。

BACKGROUND：Magnetic resonance imaging（MRI）with advantages of high contrast,no bone artifacts,and arbitrary fault orientation,are widely used in diagnosing head and neck surgery,neurosurgery and oral surgery collar surface diseases.However,artifacts formed by some metallic materials have seriously affected the image quality,and the use of these materials limits the application and accurate diagnosis of MRI in head and neck region. OBJECTIVE：To study the artifacts of hard cobalt-chromium（Co-Cr）casting alloy,soft Co-Cr casting alloy,gold alloy and 3 kinds of metallic materials in head and neck scan sequence. METHODS：Five kinds of head and neck of conventional and fast imaging sequences was performed axial scan respectively for three kinds of metal specimen placed in the center of cylindrical water phantom.Artifacts were measured,and the results were performed statistical analysis. RESULTS AND CONCLUSION：In 3 kinds of metals with the same MRI imaging sequence,gold alloy produced the smallest artifacts,which was largest in the hard cobalt-chromium,the difference between the two groups was significant（P〈0.05）;for the same metal material,spin-echo sequences produced the smallest artifacts,gradient echo sequence produced larger artifacts,echo-planar sequences produced largest artifacts with image deformation.The results suggest that,compared with non-precious metal dental restoration materials,using precious metal as dental restoration materials,can produce the minimum artifacts in the head and neck MRI.Therefore,the optimal MRI can be received via rational selecting metal dental restoration materials and imaging technology.