正常人眼球直肌Pulley功能位置的动态磁共振成像研究

目的研究正常人眼球运动动态磁共振成像（MRI）4条直肌Pulley（滑车）的功能性位置。方法采用西门子公司Sonata1.5T超导型MRI扫描仪,应用眼球运动动态MRI技术,获取20名正常人（20个眼眶）眼球原在位及上转、下转、内转、外转20度时垂直于眶轴的眼眶冠状位MRI图像。以眼球中心为原点建立三维坐标系,应用ScionImage医学图像测量软件分别测量各层面眼球垂直转动时水平直肌、眼球水平转动时垂直直肌的横截面质心。根据各层面直肌横截面质心的坐标值建立直线回归方程,分别求得眼球垂直转动时内、外直肌径路及眼球水平转动时上、下直肌径路直线回归曲线斜率变化最大的一点,即为该直肌Pulley的功能性位置。对4条直肌Pulley相对于眼球中心的坐标值（X、Y）进行统计。结果内直肌Pulley位于眼球中心后4mm,内14.7mm,下0.3mm;外直肌Pulley位于眼球中心后8mm,外9.8mm,下0.3mm;上直肌Pulley位于眼球中心后6mm,内1.6mm,上11.5mm;下直肌Pulley位于眼球中心后6mm,内4.4mm,下12.7mm。结论应用眼球运动动态MRI技术,分析眼球转动时直肌径路的变化,可证实4条直肌Pulley的存在并确定其功能位置。

The study of the location of human rectus pulleys on ocular dynamic MRI

Objective To study the location of human rectus pulley using dynamic MRI. Methods Multiple contiguous quasi-coronal MRI images perpendicular to the orbital axis were acquired for 20 orbits of 20 normal volunteers at primary gaze,supraduction,infraduction,abduction ,and addution using a 1.5 T Simens Sonata scanner. To determine inflections of the rectus paths,the area centroids of vertical recti at sec-ondary horizontal gaze and horizontal recti at secondary vertical gaze were then determined by Scion Image,a medical image manipulation software,respectively. Inflection of each rectus path was then determined objectively using linear regression on rectus mean area centroid coordinates. The functional locations of rectus pulley were defined in three dimensions using rectus path inflections at secondary gaze. Results The pulley of medial rectus was 4mm posterior,14.7mm medial and 0.3mm inferior to the globe center; it was 8 mm posterior,9.8 mm lateral,0.3 mm inferior to globe center for lateral rectus. It was6mm posterior,1.6 mm medial,11.5 superior to globe center for superior rectus. It was 6 mm posterior,4.4 mm medial and 12.7mm inferior to globe center for inferior rectus. Conclusions The existence of four rectus pulleys and their functional positions could be confirmed using dynamic ocular MRI.