脑脊液伪影在3.0TMR二维和三维液体衰减反转恢复图像上的表现

目的通过与1.5T MRI比较,探讨3.0T MR上2D和3D FLAIR图像脑脊液伪影的表现。方法 50例受试者行1.5T MR2D液体衰减反转恢复(FLAIR)成像,另外50例行3.0T MR2D和3D FLAIR成像,按4级分类法记录各受试者脑室系统、鞍上池和桥前池内脑脊液伪影:0级,无伪影;1级,伪影信号低于灰质;2级,伪影信号与灰质相似;3级,伪影信号高于灰质。将2级和3级合称为高级别。结果 1.5T MR2D FLAIR图像上,9例未见脑脊液伪影,余41例中共发现94处脑脊液伪影,其中2级最常见(54.3%),最常见于四脑室。3.0T MR2D FLAIR图像上,每例受试者至少有2处脑脊液伪影,其中3级最多见,占总伪影数50.0%。3.0T MR2D FLAIR上各部位高级别脑脊液伪影例数均明显高于1.5T。3D FLAIR图像上均未见脑脊液伪影。结论 2D FLAIR成像时,同1.5T MRI相比,3.0T MRI上高级别脑脊液伪影明显增加;但3D FLAIR图像上脑脊液信号抑制完全、无伪影。

Cerebrospinal fluid artifacts on 2D and 3D fluid-attnuated inversion-recovery images at 3.0 T MR

Objective:To study cerebrospinal fluid(CSF) artifacts on 2D and 3D fluid-attnuated inversion-recovery(FLAIR) images at 3.0 T MR by comparing with 1.5 T system.Materials and Methods:Fifty individuals were examined with 2D FLAIR images with a 1.5 T system,another fifty cases were examined with 2D and 3D FLAIR images with a 3.0 T system.CSF artifacts within ventricles,suprasellar cistern and prepontine cistern were recorded using a 4-point scale(0=no artifacts,1=artifacts intensity lower than that of gray matter,2=artifacts intensity equal to that of gray matter,3= artifacts intensity higher than that of gray matter),2 and 3 scales were defined as high grade.Results:On 2D FLAIR images with 1.5 T system,9 individuals had no CSF artifacts,and there were 94 regions with artifacts in the other 41 cases,among which,2 scale was the most frequency and occupied 54.3% of all artifacts,and forth ventricle was the most common region.On 2D FLAIR images with 3.0 T system,artifacts were seen at least two regions in every cases,and 3 scale was the most frequency and occupied 50.0%,forth ventricle and prepontine cistern were the most common regions.Compared with 1.5 T system,the ratio of high grade artifacts in ventricle and subarachnoid space was higher on 2D FLAIR images with 3.0 T system.However,there were no artifacts on 3D FLAIR images with 3.0 T system.Conclusion:Compared with 1.5 T system,high grade CSF artifacts are more often on 2D FLAIR images with 3.0 T system,but 3D FLAIR imaging can complete null CSF signal and eliminate CSF artifacts.