金属固定假牙对头部MR图像的影响研究

目的 :探讨金属固定假牙对头部 MR图像的影响。方法 :将 5 0例有金属固定假牙的病人按假牙的多少分成单牙组及多牙组 ,其中单牙组按材料的不同分铜合金、铬镍不锈钢合金、镍铬合金 3种 ,多牙组分铜合金、镍铬合金两种。分别采用 SE/ T1 WI、FSE/ T2 WI、FAST/ T2 WI行横断面、矢状面扫描 ,比较各组中不同材料在不同序列下的伪影。结果 :金属固定假牙所形成的伪影中 ,铜合金最小 ,镍铬合金最大 ;SE序列最小 ,与 FSE序列基本相同 ,FAST序列最大 ;伪影随固定假牙的数目增多而增大。结论 :金属假牙可形成伪影而致邻近组织失真 ,伪影对颅脑、颈椎的观察无影响 ,而对眼球、上颌窦及口腔结构因扫描序列材料的不同有不同程度的影响。

A Study of the Effect of Metal fixed False Teeth on Head MR Images

Objective To investigate the effects of metal fixed false teeth on head MR images.Methods The 50 patients with metal fixed false teeth were divided into single tooth group and multi-teeth group. The single tooth group were divided into three kinds(Cu alloy, chrome nickel stainless steel alloy, chrome nickel alloy), the multi-teeth group were divided into two kinds(Cu alloy, chrome nickel alloy ) according to material. The patients were inspected with the sagittal and coronary position. The sequences adopt SE-T 1WI, FSE-T 2WI, FAST-T 2WI. Metal artifacts of all groups were compared in different materials and sequences.Results The artifact were the smallest taken from Cu alloy and the largest taken from chrome nickel alloy.The artifacts with SE sequent and FSE sequent were the smallest ,but the artifacts with Fast sequence were the largest . As number of metal tooth increases the artifact enlarges.Conclusion Metal false tooth results in distortion in all MR images,but artifact does not affect the view of brain and cervical spine,but the distortion to eyeball,maxillary sinus,oral cavity is different according to the scan sequence and metirial.