正常成人活体视神经的MRI研究

目的　采用MRI在活体上测量各段视神经的直径和探讨显示视神经全程的最佳MRI扫描基线。方法　 3 0例无视功能障碍的健康志愿者做MRI检查 ,分别进行不同扫描基线的横断面扫描 ,比较不同扫描基线对视神经全程的显示情况 ;在冠状面和横断面上测量正常视神经整体的上下径和横径。结果　以下牙槽中点至枕骨大孔后缘连线为扫描基线的横断面能清楚显示视神经的三段 ,对视神经全程的显示明显优于听眶下线 (P <0 .0 5 ) ,球后 7mm、15mm眶内段视神经、视神经管内段中点和颅内段中点的横径 (包括视神经和蛛网膜下腔 )平均值分别为 (3 .81± 0 .5 5 )mm、(2 .94± 0 .3 9)mm、(2 .72±0 .40 )mm和 (3 .40± 0 .48)mm ,上下径平均值分别为 (3 .82± 0 .2 8)mm、(3 .3 4± 0 .5 1)mm、(2 .76± 0 .3 4)mm和 (2 .2 8± 0 .42 )mm。结论　MRI能够准确显示视神经及蛛网膜下腔 ,获得视神经各段的整体直径 ,为早期诊断视神经病变提供客观依据 ;以NOP线为扫描基线的横断面对视神经全程的显示最佳。

MR Imaging Investigation of Normal Human Optic Nerve in vivo

Objective To measure diameter of normal human optic nerve in vivo on MR imaging and search for the optimal scanning baseline displaying the whole optic nerve. Methods MR imaging was performed in 30 healthy volunteers without visual dysfunction.Axial images were acquired with two different baselines and the ability of them in displaying the whole optic nerve was compared.Vertical and transverse diameters of the optic nerve were measured on MR scanner. Results Axial images acquired with neuro-ocular plane (NOP line) clearly showed three segments of optic nerve and were superior to those with infraorbital-meatal line in demonstrating the whole optic nerve (P<0.05).Transverse diameter of intraorbital optic nerve located at 7mm and 15mm posterior to the globe,intracanalicular optic nerve,and intracranial optic nerve was (3.81±0.55)mm,(2.94±0.39)mm,(2.72±0.40)mm,and (3.40±0.48)mm,respectively.Vertical diameter was (3.82±0.28)mm,(3.34±0.51)mm,(2.76±0.34)mm,and (2.28±0.42)mm,respectively. Conclusion MR imaging could accurately demonstrate the optic nerve and its surrounding subarachnoid space.Axial images acquired with NOP line were the optimal sections in displaying the whole optic nerve.These might contribute to early diagnosis of optic nerve lesions.