Departments of Ophthalmology, David Geffen Medical School, University of California, Los Angeles, California 90095-7002, USA.
Invest Ophthalmol Vis Sci. 2012 Oct 25;53(11):7375-9. doi: 10.1167/iovs.12-9730.
We explored multiple quantitative measures of horizontal rectus extraocular muscle (EOM) morphology to determine the magnetic resonance imaging (MRI) measure best correlating with duction and thus contractility.
Surface coil coronal MRI was obtained in target-controlled central gaze and multiple positions of adduction and abduction in 26 orbits of 15 normal volunteers. Duction angles were determined by position changes of the globe-optic nerve junction. Cross-sectional areas, partial volumes, and location of peak cross-sections of the horizontal rectus EOMs were computed in contiguous image planes 2-mm thick spanning the EOM origins to the globe equator.
All measures correlated significantly with duction angle (P < 0.0001). The best measures obtainable in single image planes were the maximum change in the cross-sectional area between equivalent image planes, with coefficients of determination R(2) = 0.92 for medial rectus (MR) and 0.91 for lateral rectus (LR), and percentage change in maximum cross-section with R(2) = 0.79 for MR and 0.78 for LR. The best partial volume measure of contractility was the change in partial volumes in four contiguous posterior planes (R(2) = 0.86 MR and for 0.89 LR), particularly when combined with the corresponding change in partial volume for the antagonist EOM (R(2) = 0.95 for MR and LR).
EOM morphologic changes are highly correlated with degrees of duction and thus contractility. Both changes in single-plane maximum cross-sectional areas and posterior partial volumes provide accurate, quantitative measures of EOM contractility.
我们探讨了多种水平直肌眼外肌（EOM）形态的定量测量方法，以确定与牵引最相关的磁共振成像（MRI）测量方法，从而确定收缩力。
在目标控制的中心注视和内收和外展的多个位置，对 15 名正常志愿者的 26 个眼眶进行了表面线圈冠状 MRI 检查。通过眼球视神经交界处的位置变化确定牵引角度。在 EOM 起源到眼球赤道的 2 毫米厚的连续图像平面上计算水平直肌 EOM 的横截面积、部分体积和峰值横截面积的位置。
所有测量值与牵引角度均呈显著相关（P < 0.0001）。在单个图像平面上可获得的最佳测量值是等效图像平面之间的横截面积最大变化，内侧直肌（MR）的决定系数 R²为 0.92，外侧直肌（LR）为 0.91，最大横截面积的百分比变化 R²为 0.79 MR 和 0.78 LR。最佳的收缩力部分体积测量是四个连续后平面的部分体积变化（MR 为 R²=0.86，LR 为 0.89），特别是当与拮抗 EOM 的相应部分体积变化结合使用时（MR 和 LR 的 R²=0.95）。
EOM 形态变化与牵引程度密切相关，从而与收缩力相关。单平面最大横截面积和后部分体积的变化均可提供准确、定量的 EOM 收缩力测量值。
