Extraocular muscle deformation assessed by motion-encoded MRI during eye movement in healthy subjects
Extraocular muscle deformation assessed by motion-encoded MRI during eye movement in healthy subjects
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DOI：
10.1167/7.14.5
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发表时间：
2007-01-01
影响因子：
1.8
通讯作者：
Bergamin, Oliver
中科院分区：
文献类型：
--
作者：
Piccirelli, Marco;Luechinger, Roger;Bergamin, Oliver
常规磁共振成像（MRI）可用于评估形态变化，但不适用于评估均匀结构内部的变形（M. D. Abramoff， A. P. Van Gils， G. H. Jansen, & M. P. Mourits, 2000）。由于没有内在的对比可以成像来区分肌肉收缩的异质模式，沿着眼外肌（EOMs）的长度的形态学变化不能在宏观上检测到。然而，一种能够直接编码运动的成像方法可以为EOMs的不均匀变形动力学提供证据。因此，我们开发了一种方法来获取眼动过程中EOMs的运动编码MRI图像。七名健康受试者凝视一个水平正弦振荡目标。一个小的表面线圈被放置在右轨道的前面。水平直肌和非收缩视神经的收缩和舒张情况得到了可靠的跟踪。从第3个时间框架开始（从开始左右眼运动持续1 s算起= 140 ms），可区分眼膜的差异收缩性。从第6个时间框架（= 350 ms）开始，收缩的内侧直肌肌腹可以从后段和前段区分出来。总之，运动编码MRI在不使用物理标记的情况下解决了健康受试者运动EOM节段的异质性收缩。
Conventional magnetic resonance imaging (MRI) is useful for assessing morphological changes but not for assessing deformations inside homogeneous structures (M. D. Abramoff, A. P. Van Gils, G. H. Jansen, & M. P. Mourits, 2000). Since no intrinsic contrast can be imaged for distinguishing heterogeneous patterns of muscle contraction, morphological changes along the length of the extraocular muscles (EOMs) are not macroscopically detectable. However, an imaging method that is able to directly encode motion could give evidence about the dynamics of the inhomogeneous deformation of the EOMs. Thus, we developed a method for acquiring motion-encoded MRI images of the EOMs during eye movements. Seven healthy subjects gazed at a horizontal sinusoidally oscillating target. A small surface coil was placed in front of the right orbit. The contracting and relaxing horizontal rectus muscles and the noncontracting optic nerve were reliably tracked. The differential contractility of the EOMs could be distinguished from the third time frame on (= 140 ms from the beginning of the right to left eye movement lasting 1 s). The muscle belly of the contracting medial rectus muscle could be distinguished from the posterior and the anterior segment from the sixth time frame on (= 350 ms). In conclusion, motion-encoded MRI resolved the heterogeneous contraction of moving EOM segments in healthy subjects without using physical markers.