颞骨岩锥后壁蛛网膜颗粒的影像学表现

Finding and differentiation of arachnoid granulations in the posterior wall of temporal bone

目的:探讨颞骨岩锥后壁蛛网膜颗粒的影像学特征并与其它疾病进行鉴别诊断。方法:回顾性分析5例6耳颞骨岩锥后壁蛛网膜颗粒压迹的HRCT,薄层MRI表现特点。结果:4耳颞骨岩锥后壁蛛网膜颗粒在HRCT上表现为分叶状骨质缺损区,内部均匀低密度,边缘无硬化及钙化,周围无软组织肿块,相邻的前庭导水管及半规管未受累。在薄层MRI上6耳颞骨岩锥后壁蛛网膜颗粒在T1WI、T2WI、FLAIR上表现为与脑脊液相同的信号,并可见其内显示呈放射状分布的细条状的纤维索条影,膜性半规管形态结构未受累。增强后无强化。结论:颞骨岩锥后壁蛛网膜颗粒是见于老年人酷似恶性骨质破坏的正常变异,其特征是所含脑脊液内有纤维分隔,据此能够与此部位的其它病变区别开来。

Objective：To investigate the imaging features of arachnoid granulations in the posterior wall of temporal bone and to make a differentiation.Methods：The features of arachnoid granulations in the posterior wall of 6 temporal bones in 5 cases were analyzed retrospectively by HRCT and thin-slice MRI.Results：Lobulated bone defects areas,which were homogenous isodensity without osteosclerotic rim or calcification,were showed in 4 ears of arachnoid granulations in the posterior wall of temporal bone on HRCT,and no mass surrounded the lesions was fownd to involve in neighbouring vestibular aqueduct and semicirculars.The same signals as cerebrospinal fluid were showed by all T1WI,T2WI,FLAIR sequences in 6 ears of arachnoid granulations in the posterior wall of temporal bone on thin-slice MRI,and radiative slim fibers were seen inside it.Membranous semicirculars were not involved.It had no enhancement after contrast.Conclusion：Arachnoid granulations in the posterior wall of temporal bone were normal varieties encapsulating cerebrospinal fluid separated by fibrous septums.It occurred in old ages in the form of malignant bone destruction.It could be differentiated from other lesions located in this area.