四种序列1.5 T磁共振成像口腔金属冠引起伪影程度的对比

摘要

Objective To observe and evaluate the metallic artifacts caused by dental metal crowns with four se-quences of magnetic resonance imaging in T2*/GRE,T2W/IR,T2W/FSE and T1W/SE. Methods Crowns made from four different materials( Co-Gr,Ni-Gr,Ti alloy and Pure-Ti)were included in this study. The experimental animal was a ripe crossbreed dog and the crowns were fabricated for its upper right second premolar. Each mental crown was examined by a head MRI(1. 5 T)scan with four sequences of T2*/GRE,T2W/IR,T2W/FSE and T1W/SE,respectively. The existence and ex-tent of the artifacts were assessed and compared. Results All metal crowns produced artifacts. The sequence T2*/GRE exhibited significantly wider artifact than the others(P<0. 05). For any of the test alloy crown,artifacts were seen on more MRI slices in the sequence T2*/GRE than in other three sequences which produced similar artifact presentation(P<0. 05). Conclusion A-nalysis of the artifact size and artifact-related imaging slices demonstrated that among all the four sequences,T2*/GRE has the strongest influence while the other three sequences contributed equally to artifact generation.%目的：探讨在有金属冠存在的情况下，1.5 T磁共振成像T2*/梯度回波序列（ GRE）、T2W/反转恢复自旋回波（IR）、T2W/快速自旋回波序列（FSE）、T1W/自旋回波序列（SE）4种序列产生伪影的程度。方法给实验犬依次佩戴钴铬合金、镍铬合金、低钛合金、纯钛金属4种金属冠，按序进行4种序列常规1.5 T磁共振成像的颅脑扫描，分别测量4种序列在4种金属冠存在下所产生伪影的最大面积并计数金属伪影涉及图像的层数，对测量结果进行统计分析。结果各金属冠在1.5 T磁共振成像4种序列均产生了伪影。4种序列钴铬合金、镍铬合金、低钛合金、纯钛金属伪影最大面积比较，差异有统计学意义（ P＜0.05）；其中T2W/IR组、T2W/FSE组、T1W/SE组较T2*/GRE组均降低（P＜0.05）。结论金属冠引起T2*/GRE序列伪影最大，其他3种序列产生伪影程度相近。