MRI of the intraorbital ocular motor nerves on three-dimensional double-echo steady state with water excitation sequence at 3.0T.

Abstract

To explore the capability of three-dimensional double-echo steady state with water excitation sequence (3D-DESS-WE) to determine the intraorbital ocular motor nerves (IOMN). A 3.0T scanner was applied to investigate 30 healthy volunteers based on the 3D-DESS-WE sequence. Dunnett t test was conducted to evaluate the signal intensity (SI) of the left oculomotor nerve (CNIII), frontal white matter, cerebrospinal fluid (CSF), and lateral rectus (LR). The oculomotor nerve's detectability, trochlear nerve (CNIV), and abducens nerve (CNVI) were evaluated independently by two observers. The average assessment scores were determined, and interobserver variability for these nerves' detectability was determined using a weighted kappa analysis. The SI of CNIII is similar to that of the frontal white matter (t = 2.26, P > 0.05), lower than the CSF, and higher than the LR (t = 3.81, - 3.45, P < 0.05). The average scores of the superior division of CNIII and the branch to medial rectus (MR), inferior rectus (IR), inferior oblique (IO), CNIV, and CNVI were 3.01, 3.07, 3.78, 2.98, 2.88, and 3.97, respectively. The interobserver variability was excellent (κ = 0.83-1.00). The 3D-DESS-WE sequence shows an ability to detect the IOMN course in healthy volunteers effectively.