Demer J L, Miller J M
Jules Stein Eye Institute, UCLA School of Medicine 90024-7002, USA.
Invest Ophthalmol Vis Sci. 1995 Apr;36(5):906-13.
To study the size and contractile changes of the normal superior oblique (SO) muscle using high-resolution magnetic resonance imaging (MRI), and to evaluate the abnormalities in these characteristics produced by SO palsy.
Multiple coronal MRI image planes were obtained using a surface coil to span the antero-posterior extent of each orbit and were repeated in multiple directions of gaze. Digital image analysis was used to measure muscle cross-sectional area for evaluation of size and contractility.
Data for 16 orbits of 11 subjects without SO palsies established norms for morphology and contractility. On SO contraction in down gaze, maximum cross sectional area was significantly (P < 0.001) greater than on relaxation in up gaze, and the point of maximum cross-section shifted posteriorly with contraction. In seven subjects with clinically unilateral chronic SO palsies, the affected muscle was significantly smaller than normal (P < 0.001) and lacked contractile changes; clinically normal fellow SO muscles exhibited normal cross-sections and contractile changes.
High-resolution MRI, coupled with quantitative morphometric analysis, can demonstrate the size and contractility of the normal SO muscle. The technique, which can be employed using widely available clinical equipment, is also sensitive enough to detect anatomic and functional changes expected in chronic SO palsies.
使用高分辨率磁共振成像（MRI）研究正常上斜肌（SO）的大小和收缩变化，并评估SO麻痹所导致的这些特征异常。
使用表面线圈获取多个冠状面MRI图像平面，以覆盖每个眼眶的前后范围，并在多个注视方向重复进行。采用数字图像分析测量肌肉横截面积，以评估大小和收缩性。
11名无SO麻痹受试者的16个眼眶数据建立了形态学和收缩性规范。在向下注视时SO收缩时，最大横截面积显著（P < 0.001）大于向上注视放松时，且最大横截面点随收缩向后移动。在7名临床单侧慢性SO麻痹患者中，患侧肌肉明显小于正常（P < 0.001）且缺乏收缩变化；临床正常的对侧SO肌肉表现出正常的横截面和收缩变化。
高分辨率MRI结合定量形态测量分析能够显示正常SO肌肉的大小和收缩性。该技术可使用广泛可用的临床设备进行，并且足够敏感以检测慢性SO麻痹中预期的解剖和功能变化。
