Carteret M, Massin M, Cabanis E A
CHNO des Quinze-Vingts, Service de neuro-radiologie, Paris.
J Fr Ophtalmol. 1992;15(10):537-42.
Dynamic mode magnetic resonance imaging (DMMRI) allows good visualization of the oculomotor muscles and allows their dimensions to be measured both when they contract and when they relax. The accuracy of this method has been checked and the measurements of the cross section of medial and inferior recti and of superior obliques can be considered to be valid. Measurements of length are inaccurate and the other muscles are not perpendicular to the sectional planes generally used in MRI of the head. By means of a fixation scale situated in the tunnel of the machine, the maximum diameter of medial recti in their thickest part was evaluated in two girls affected by a Stilling Duane retraction syndrome of the left eye. Two direction of the gaze were explored: 25 degrees at the right, then 25 degrees at the left, these angles being obtained by the fixation of particular points of the tunnel scale. The measurements have been made on axial sections, then on coronal sections, both medio-orbital and apical. The first finding is that the diseased medial rectus is much bigger than the healthy one. When relaxed, its thickness is about the same as that of the contracted normal muscle. Coronal orbital cross sections clearly show recession of the belly of the diseased muscle towards the back of the orbit. When contracted it stays in the apical plane and when relaxed in the medio-orbital plane. Lastly the relaxation is much weaker for the pathological muscle than for the healthy one.(ABSTRACT TRUNCATED AT 250 WORDS)
动态模式磁共振成像（DMMRI）能够很好地显示动眼肌，并能在其收缩和放松时测量其尺寸。该方法的准确性已经得到验证，内直肌、下直肌和上斜肌的横截面积测量结果可认为是有效的。长度测量不准确，而且其他肌肉与头部MRI通常使用的截面不垂直。通过位于机器通道内的固定刻度，对两名患有左眼斯蒂林 - 杜安眼球后退综合征的女孩的内直肌最厚部分的最大直径进行了评估。探索了两个注视方向：向右25度，然后向左25度，这些角度通过固定通道刻度的特定点获得。测量在轴位切片上进行，然后在冠状切片上进行，包括眶中部和眶尖部。第一个发现是患病的内直肌比健康的内直肌大得多。放松时，其厚度与收缩的正常肌肉大致相同。冠状眶部横截面清楚地显示患病肌肉的肌腹向眶后部退缩。收缩时它位于眶尖平面，放松时位于眶中部平面。最后，患病肌肉的放松程度比健康肌肉弱得多。（摘要截取自250字）
