扫描参数变化对FLAIR序列金属伪影的影响

Influence of Change of Scanning Parameters on Metal Artifacts in FLAIR Sequence

目的探讨不同扫描参数对FLAIR序列金属伪影的影响,以通过调整扫描参数来减小金属伪影。方法选用镍铬合金制成左下6标准桩核冠模型。应用1.5 T MRI扫描仪对桩核冠模型行横断面FLAIR扫描,扫描参数为西门子1.5T MR扫描仪的推荐值。保持其它参数与标准扫描序列参数一致,逐一改变以下各参数进行成像:TR、TE、FOV、Matrix、BW、NEX、ETL、Thk、FA。确定伪影最大的层面并测量伪影面积。应用SAS V8统计学软件进行统计学分析。结果调整不同FOV值,不同Matrix值及FA值,镍铬合金伪影大小差异有统计学意义(F值分别为F=67.04,F=48.75,F=5.61,P<0.05)。结论在FLAIR序列中,可以通过减小视野、增加矩阵,增大翻转角减小金属伪影。

Objective To discuss the influence of different scanning parameters on the metal artifacts in FLAIR sequence,in order to reduce the artifacts by adjusting the scanning parameters.Methods Ni-Cr alloy were molded into standard post-core-crown posterior tooth model.The model were scanned by 1.5T MR scanner.Axial FLAIR sequence was scanned.The scan parameters was the recommended values for the SIEMENS 1.5T MR scanner.Changing the following parameters:TR,TE,FOV,Matrix,BW,NEX,ETL,Thk,FA one by one without affecting the image quality.To determine the section of the largest artifacts and measure the area.Statistical testing was performed.Results There was statistically significant differences of metal artifacts in different FOV values(F=67.04,P<0.001).There was statistically significant differences of metal artifacts in different Matrix values(F=48.75,P<0.001).There was statistically significant differences of metal artifacts in different FA values(F=5.61,P=0.04).Conclusion In FLAIR sequence,decreasing the FOV,increasing Matrix and FA can decrease the artifacts.