MRI检查中不同口腔金属材料伪影面积的研究

目的比较不同口腔金属材料在磁共振成像不同序列中产生的伪影面积，为临床选择适宜磁共振成像检查的金属修复材料和成像序列提供实验依据。方法选用口腔科临床常用铸造金属材料（银钯合金、金钯合金、金合金、镍铬合金、钴铬合金、钛合金和纯钛）制作立方体模型，置于充满蒸馏水的圆筒状塑料容器中，并以瓷块作为对照，采用三种头颈部常用序列（SET1WI、FSET2WI、GRET2WI）进行检查，测量并分析比较伪影面积。结果方差分析显示，金属材料（F=27．920，P〈0．001）和扫描序列（F=52．771，P〈0．001）均对伪影面积有显著性影响。贵金属合金的伪影面积最小，与对照组比较差异无统计学意义（P〉0．05），而钛合金和纯钛出现中度伪影，镍铬合金、钴铬合金存在重度伪影（P〈0．05）。三种序列中，GRET2WI序列产生的伪影面积最大。结论合理选择金属材料和成像序列可以减小MRI金属伪影。

Research on artifacts in MRI examination of different dental metallic materials

Objective To evaluate the artifact sizes of three magnetic resonance imaging （MRI） sequences caused by different kinds of metallic dental materials. Methods Cubical samples of dental casting alloy （ Ag-Pd al-loy, Au-Pd alloy, gold alloy, Ni-Cr alloy, Co-Cr alloy, titanium alloy and pure titanium） were placed in a cylindrical plastic vessel filled with distilled water. Ceramic pieces were used as control. Images were performed by means of 1. 5 T MRI apparatus with 3 different sequences commonly used in brain MRI sequences. MRI artifact area of different metal materials and different sequences was calculated and compared. Results ANOVA of factorial design indicated significant differences among different materials （ F = 27. 920, P 〈 0. 001 ） and 3 sequences （ F = 52. 771, P 〈 0. 001 ）. Compared to control material the precious alloys produced the least artifact while titanium alloy, pure titani- um the middle level and Ni-Cr alloy, Co-Cr alloy the largest. Among the 3 imaging sequences, GRET2 produced the largest artifact. Conclusion Selection of specific metal material and imaging sequence can minimize the metal arti- facts in MRI.