Piccirelli Marco, Luechinger Roger, Sturm Veit, Boesiger Peter, Landau Klara, Bergamin Oliver
Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
Invest Ophthalmol Vis Sci. 2009 Nov;50(11):5189-96. doi: 10.1167/iovs.08-3182. Epub 2009 Jun 10.
To study extraocular muscle (EOM) function, the local physiologic contraction and elongation (deformation) along human horizontal EOMs were quantified by using motion-encoded magnetic resonance imaging (MRI).
Eleven subjects (healthy right eye) gazed at a target that moved horizontally in a sinusoidal fashion (period, 2 seconds; amplitude, +/-20 degrees), during MRI with an optimized protocol. In addition, EOM longitudinal deformation in two patients with Duane's syndrome type I was analyzed. The horizontal EOMs and the optic nerve were tracked through 15 time frames, and their local deformation was calculated. Eight segments were separated along the EOMs and left-to-right and right-to-left eye movements were compared.
In healthy subjects, the maximum EOM deformation was situated at approximately two thirds of the muscle lengths from the scleral insertions. The EOM deformations were similar for the entire movement range as well as in both movement directions. In the two patients with Duane's syndrome type I, the abnormal innervation of lateral rectus muscle affected specific EOM segments only. The posterior muscle segments contracted and the anterior muscle segments relaxed during adduction.
Motion-encoded MRI is a useful technique for advancing the understanding of the physiology and pathophysiology of EOMs in humans during eye movement.
为研究眼外肌（EOM）功能，通过使用运动编码磁共振成像（MRI）对人水平眼外肌的局部生理收缩和伸长（变形）进行量化。
11名受试者（右眼健康）在采用优化方案的MRI检查期间，注视以正弦方式水平移动的目标（周期为2秒；幅度为±20度）。此外，分析了2例I型杜安综合征患者的眼外肌纵向变形。在15个时间帧内追踪水平眼外肌和视神经，并计算其局部变形。沿眼外肌分离出8个节段，并比较了左右眼的运动。
在健康受试者中，眼外肌最大变形位于距巩膜附着点约三分之二肌长处。在整个运动范围内以及两个运动方向上，眼外肌变形均相似。在2例I型杜安综合征患者中，外直肌的异常神经支配仅影响特定的眼外肌节段。内收期间，肌肉后段收缩，前段松弛。
运动编码MRI是一种有助于增进对人眼运动期间眼外肌生理和病理生理学理解的有用技术。
