正常成人眶尖的CT和MRI研究

Study of normal orbital apex with CT and MRI

目的 明确CT和MRI检查对眶尖正常结构的显示能力和正常表现。方法 对40例正常成人分别进行研究,20例行CT检查,常规行横断及冠状位扫描。20例行MRI检查, MRI检查行横断、冠状及斜矢状位扫描,常规T1WI、T2WI序列。结果 HRCT显示眶尖骨性结构及交通清晰;常规CT及MRI显示眶尖内结构:①视神经:100%显示,其中MRI27.5%可区分视神经和蛛网膜下腔。②MRI冠状位动眼神经显示率85%,鼻睫神经22.5%,外展神经22.5%,额神经、泪腺神经及滑车神经未显示。CT不能显示上述神经。③CT显示眼动脉95%,显示眼上静脉70%。MRI显示上述结构分别为95%、47.5%。④显示总腱环及眼外肌以冠状位为佳。总腱环只能在MRI显示,显示率达85%。眼外肌中,上斜肌显示率CT为80%,MRI为95%,其余眼外肌均100%显示。⑤眶尖脂肪分布:肌锥内脂肪均显示,肌锥外脂肪CT显示率为85%,MRI显示率为100%,眶上裂区脂肪CT为45%,MRI为77.5%。结论 HRCT能清晰显示眶尖骨性构成,常规CT及MRI检查也能显示眶尖内重要解剖结构,以MRI更优。对眶尖内神经及总腱环与眼外肌起始部观察尚有待于进一步提高。

Objective To study the appearance of the orbital apex and thestructures inside it with high-resolution CT and MRI on the basis of thefindings of cross-sectional anatomy. Methods 40 healthy volunteers wereequally divided into 2 groups.The 20 subjects of Group 1 were examinedwith axial and direct scanning of high-resolution CT and those ofGroup 2 with axial,coronal and oblique sequences of MRI. Results ①CT displayed clearly the bony structures of the orbital apex. ②MRI demon-strated the 2 optic nerves in all the volunteers and the cerebrospinalfluid in subarachnoid space surrounding the nerves in 27.5% of thevolunteers. ③MRI demonstrated the oculomotor nerve in 85%,the nasociliarynerve in 22.5% and the abducent nerve in 22.5% of the subjects. ④CTshowed the ophthalmic nerve in 95% and superior ophthalmic nerve in70% of the volunteers while MRI revealed the ophthalmic arteries in 95%and superior ophthalmic veins in 47.5% of the volunteers.⑤Coronalscanning was efficient to detect the Zinn,s ligments and extraocularmuscles. ⑥CT and MRI showed intraconal fatty tissue in all thevolunteers and extraconal fatty tissue was shown in 85% of the subjectswith CT and in all the subjects with MRI.Conclusion ①CT is a goodtechnique to show the bony structure of the orbital apex. ②Coronal SET1WI and FSE T2WI are efficient to reveal the region surrounding theorbital apex,extraocular muscles,Zinn,s ligment,nerves and bloodvessels.MRI provides more information about these structures than CT.