骶椎神经鞘瘤MRI诊断

Magnetic Resonance Imaging Diagnosis of Sacral Schwannoma

背景:探讨骶椎神经鞘瘤的侵犯特点与MRI表现特征。方法:观察26例骶椎神经鞘瘤的MRI表现,根据生长部位、侵犯范围及有无囊变、齿状边缘征,进行分型、分组测量瘤体最大径。比较型间及组间瘤体最大径的差异。对照分析瘤实质T2WI信号、强化效应及HE染色组织学表现。结果:1型4例,2型5例,3型10例,4型7例。骶前软组织肿块出现率高于骶板后(X2 = 13.066, P = 0.011)。骶椎中线与中线旁骨质破坏各5例、14例。第3型瘤体最大径大于其它型(t = 2.655, P = 0.014)。8例GISS瘤体最大径超过18例非GISS(t = 3.027, P = 0.006)。齿突边缘征阳性12例与阴性14例间瘤体最大径差异无显著性(t = 1.896,P = 0.07)。囊变组12例的瘤体最大径、病程均长于非囊变组14例(t = 2.928, P = 0.007;t = ?2.187, P = 0.039)。I区呈T2WI稍高信号、明显强化,对应Atoni A区;II区呈T2WI高信号、无强化或轻微强化,对应Atoni B区。结论:骶椎神经鞘瘤具有偏心性破坏和骶前侵犯特性。T2WI双重信号及内在差异性强化是该瘤的MRI表现特征。

Background: To assess the invasive feature and characteristic MRI manifestations of sacral schwannoma. Methods: The maximal dimension of tumoral mass (MDTS) was measured in the 26 patients with sacral schwannoma, who were typed and grouped based on tumoral site and invasive extent, presences of tumoral cystic degeneration and dentate margin sign. The differences of MDTS were compared between types and between groups. The signal appearances on T2-weighted image and post-contrast enhancement pattern were observed of the tumoral parenchyma, and correlated to histologic findings of HE stain. Results: The 26 patients included 4 cases of type 1, 5 of type 2, 10 of type 3, and 7 of type 4. The incidence of pre-sacral soft tissue mass surpassed that of post-laminal region(X2 = 13.066, P = 0.011). Osteolysis was revealed in midline sacrum in 5 patients and in para-midline sacrum in 14 patients. The MDTS of type 3 was larger than that of rest types (t = 2.655, P = 0.014). The MDTS of 8 cases of giant invasive sacral schwannoma (GISS) exceeded that of 18 cases of non-GISS (t = ?3.027, P = 0.006). No significant difference was shown between the 12 patients with positive dentate margin sign and the 14 patients with negative (t = 1.896, P = 0.07). Both MDTS and duration in 12 patients with cystic degeneration exceeded those in 14 with no cystic degeneration (t = 2.928, P = 0.007;t = ?2.187, P = 0.039;respectively). Region I was demonstrated with mild hyperintensity on T2-weighted image, marked enhancement and correlated to Atoni A area;while region II was noted with hyperintensity on T2-weighted image, mild or no enhancement and correlated to Atoni B area. Conclusion: Sacral schwannoma possesses the features of eccentric osteolysis and pre-sacral infiltration. The dual signal appearances on T2-weighted image and the intrinsic post-contrast enhancement discrepancy comprise the characteristics of MRI appearances of this tumor.