中文摘要：

目的：比较卧位MR与坐位CT排便造影2种成像技术在评价肛提肌形态及功能方面的差异。方法：对17名健康志愿者（女8例,男9例,22-24岁）行仰卧位MR和坐位CT排便造影检查。分静息、缩肛和排便3期获取盆底的冠状面图像,对肛提肌行形态学测量。结果：MR图像显示肛提肌在静息期呈穹隆状;缩肛期呈平台状,肛提肌横行部的不同部分出现矛盾运动,其中点下降（3.45±0.29）mm,内点上升（5.60±2.39）mm;排便期呈盆状,中点下降（10.76±1.10）mm,内点下降（10.47±1.29）mm。CT图像显示肛提肌在静息期呈漏斗状;缩肛期呈平台状,肛提肌横行部,中点上升（6.45±2.05）mm,内点上升（13.39±3.93）mm;排便期呈盆状,中点下降（4.40±2.01）mm,内点下降（17.45±4.05）mm。结论：卧位MR与坐位CT排便造影在评价肛提肌形态及功能方面差异显著。

英文摘要：

Objective：To compare the difference of lying MR defecography and sitting CT defecography in demonstrating the morphology and the function of the levator ani.Methods：Lying MR defecography and sitting CT defecography data sets from 17 normal volunteers were studied： 8 females and 9 males,aged 22~24 yrs.The coronal plane images of the pelvis obtained during the three standard phases of rest,squeeze and defecation.Morphometric measurements of the levator ani were performed.Results：MR images revealed the levator ani was dome-shaped at rest in lying position;it was becoming plate-shaped during squeeze,the different part of the transverse levator did the contradictory motion： the mid height of the transverse levator descended（3.45±0.29） mm,the inner height ascended（5.60±2.39） mm;and it was becoming basin-shaped during defecation,the mid height descended（10.76±1.10） mm,the inner height descended（10.47±1.29） mm.CT images revealed that the levator ani was funnel-shaped at rest in sitting position;it was becoming plate-shaped during squeeze,the mid height of the transverse levator ascended（6.45±2.05） mm,the inner height ascended（13.39±3.93） mm;and it was becoming basin-shaped during defecation,the mid height descended（4.40±2.01） mm,the inner height descended（17.45±4.05） mm.Conclusion：Significant difference was present between lying MR defecography and sitting CT defecography in demonstrating the morphology and the function of the levator ani.