Abstract
Purpose: :
To understand extraocular muscle (EOM) function, the physiologic contraction and elongation (deformation) along five human EOMs were quantified using 3D datasets with perpendicular taglines.
Methods: :
Two subjects (healthy right eye) gazed at a target that moved horizontally in a sinusoidal fashion (period 2s, amplitude ±20°), during MR imaging with an optimized protocol. The horizontal rectus muscles and the optic nerve were tracked through 15 time frames and their local deformation was calculated. The deformation profiles were compared for 2D and 3D datasets. In addition, the deformations of the vertical rectus muscles and the superior oblique muscle were quantified using 3D data.
Results: :
The deformation profile based on 2D and 3D data showed common characteristics such as the inhomogeneous deformation for the horizontal rectus muscles or the position of the deformation maxima. The results for 3D data were in accordance with other published results (1), based on 2D techniques. The small deformations of the vertical rectus muscles and the superior oblique muscle were expected for the horizontal eye movements.
Conclusions: :
The 3D motion-encoded MRI acquisition technique used in this study enabled to track the EOM deformation in a tolerable scan time. Further studies plan to investigate the ability of this technique to differentiate pathologic from the physiologic muscle contraction pattern.(1) Piccirelli M, Luechinger R, Sturm V, Boesiger P, Landau K, Bergamin O: Local deformation of extraocular muscles during eye movement. IOVS 2009 Nov;50(11):5189-96.
Keywords: imaging/image analysis: non-clinical • eye movements • extraocular muscles: structure