颞下窝原发肿瘤的MR诊断

MR diagnosis of tumor originating in the infratemporal fossa

目的:探讨颞下窝原发肿瘤的MR表现,提高其诊断正确率。方法:回顾性分析12例经手术及病理证实的颞下窝原发肿瘤的MR资料。结果:12例肿瘤均起源于颞下窝,其中神经鞘瘤5例,神经纤维瘤3例,纤维血管瘤1例,滑膜肉瘤1例,软骨肉瘤2例。神经源性肿瘤边界清晰,信号较均匀,多呈等T1、等T2信号,强化均匀,神经鞘瘤内常可见囊变。纤维血管瘤T1呈稍低信号,T2呈高信号,多呈明显均匀强化。滑膜肉瘤T1呈均匀等信号,T2呈较均匀稍低信号,呈均匀中度强化。软骨肉瘤边界不清,形态不规则,呈不均匀长T1、长T2信号,强化不均匀,可见下颌骨升肢及髁状突骨质破坏。结论:MR可以准确显示肿瘤部位、边界及侵犯范围,对神经源性肿瘤和纤维血管瘤可以做出定性诊断。

Objective： To evaluate MR imaging findings of tumor originating in the infratemperal fossa so as to promote the diagnostic accuracy. Methods： All tumors arising from infratemporal fossa were confirmed by pathology and surgery. MR appearance were analyzed retrospectively. Results： The tumors included 5 neurilemmomas, 3 neurofibromas, 1 angiofibroma, 2 cbondrosarcomas, 1 synovial sarcoma. Neurogenic tumors had well--defined border and regular shape with isointense signal on T1WI and hyperintense signal on T2WI. Neurofibromas showed homogeneous enhancement after administration of contrast medium while neurilemmomas showed heterogeneous enhancement. On MR imaging angiofibromas were isointensc compared to muscle on T1WI, hyperintense on T2WI with obvious enhancement after administration of contrast medium. The synovial sarcomas were homogeneously isointense on T1-weighted studies and were hypointensc relative to muscle on T2-weighted studies. After administration of contrast material, the mass enhanced slightly more than the surrounding muscles. Chondrosarcoma＇s border was ill-defined, showing heterogeneous hypointensc signal on T1WI, inhomogenous hyperintensc signal on T2WI and heterogeneous enhancement after administration of contrast medium. Conclusion： MRI can demonstrate optimally the border and the extent of the tumors in infratemporal fossa. MR imaging can contribute to diagnosis of neurogenic tumor and angiofibroma.