频率编码方向对垂体微腺瘤3.0T MR图像质量的影响

Pituitary micro-adenoma imaging on 3.0T MR scanner:the effect of different frequency encoding directions on the image quality

目的:评价不同的频率编码方向对于垂体微腺瘤3.0T MR图像质量的影响,以指导该病MRI参数的选择。方法:选取14例临床拟诊为垂体微腺瘤患者,使用3.0T MR扫描仪分别于垂直频率编码方向(上/下)和水平频率编码方向(左/右)上行冠状面T1WI、T2WI及T1WI增强扫描。由两位神经放射学专家按照一个5级评分标准对所得图像进行评分。评分标准如下:能极好地显示瘤体,4分;足够用于诊断,3分;能用于诊断,2分;不能用于诊断,1分;无阳性发现,0分。将两位专家对每组的评分取平均数作为最终评分,两组间评分的比较采用配对样本的符号秩和检验。结果:除2例患者在两组图像中均无阳性发现外,其余12例患者均被诊断为垂体微腺瘤。对于T2WI平扫图像和T1WI增强图像,左/右频率编码方向所获得图像质量优于上/下频率编码方向所获得图像,且二者差异具有统计学意义(P<0.05)。对于T1WI平扫图像,二者差异无统计学意义(P>0.05)。结论:使用3.0T MR扫描仪进行垂体微腺瘤成像,频率编码方向对T2WI平扫图像和T1WI增强图像质量影响较大,水平(左/右)频率编码方向扫描所得图像的质量比垂直(上/下)频率编码方向扫描所得图像质量更佳。

Objective：To evaluate the effect of different frequency coding directions on the quality of pituitary micro-adenoma images acquired with 3.0T MR scanner,so as to help to set MR parameters for the patients suffering from pituitary micro-adenoma.Methods：Fourteen patients,who were suspected of pituitary micro-adenoma,were studied prospectively and evaluated by 3.0T MRI scanning with both horizontal and vertical frequency encoding directions.Data were acquired on coronal T1WI,T2WI and T1W GD-enhanced images.Two neuroradiologists rated the images＇ quality on a five-point scale.Score 4=the adenoma could be displayed excellently;Score 3=explicit radiological diagnosis could be easily made by radiologists;Score 2=ambiguous radiological diagnosis could be made;Score 1= the pituitary was not well displayed;Score 0=nothing could be found from the images.Wilcoxon signed rank test was used to analyze the data.Results：No positive findings were detected in 2 of 14 patients.other 12 were diagnosed as having pituitary micro-adenoma.When frequency encoding direction was set on left/right,quality of T2-weighted and T1-weighted GD-enhanced images was better than the inferior/superior direction group（P0.05）.However,T1-weighted images of two groups had no significant difference（P0.05）.Conclusion：Our results indicate that left/right frequency encoding direction should be set when pituitary images are acquired on 3.0T MR scanner in patients with suspected microadenoma.