MRI对四肢神经鞘瘤的诊断价值

Diagnostic value of MRI in peripheral schwannoma of extremities

目的:探讨四肢神经鞘瘤的MRI表现,提高MRI对四肢神经鞘瘤的诊断率。方法:回顾性分析23例经手术病理证实的四肢神经鞘瘤的MRI资料,其中上肢8例,下肢15例。23例均行常规MRI扫描,包括自旋回波(SE)T_1WI,快速自旋回波(FSE)T_2 WI和SE T_1 WI增强扫描。结果:23例肿瘤有20例呈椭圆形或梭形,边界清楚光滑,14例位于神经血管束走行区,沿神经走行方向生长,并与神经偏心性相连,9例未追踪到起源神经。21例有完整包膜。绝大多数神经鞘瘤T_1WI呈中等至低信号,所有肿瘤T_2WI呈不均匀高信号或高低混合信号,增强扫描有不均匀强化。其中显示靶征6例,神经出入征14例,脂肪包绕征10例,脂肪尾征12例。结论:MRI有利于明确肿瘤的位置和范围,靶征、神经出入征、脂肪包绕征和脂肪尾征对诊断有重要价值。

Objective： To discuss the MRI findings of peripheral schwannoma of extremities and elevate the usefulness of MRI in diagnosis of the tumor. Methods： The MRI features of 23 patients with pathologically proved peripheral schwannomas of the extremities were retrospectively analyzed. The locations of the tumor were upper limb（8 cases）and lower limb（15 cases）. Scan sequences included SE T1WI, FSE T2 WI and SE T1WI before and after injection of Gd-DTPA. Results.. Twenty tumors were oval shaped, well-defined, 14 located in neurovascular bundles with the extend along the nerve distribution and they were continued with parent nerve eccentrically, 9 were separated from nerve, 21 showed whole capsule. Most of the masses appeared iso-/hypo-signal intensities on TlWI and all tumors appeared heterogeneous hyper-signal intensities or mixed hypo-intense and hyper-intense on T2WI. After contrast administration, the lesions showed inhomogeneous enhancement. The target sign was seen in 6 cases, nerve entering and exiting the tumor in 14 cases, fa＇t-encireling sign in 10 cases, fat-tail sign in 12 cases. Conclusion： MRI is useful in defining the location and extent of lesions. ＂Target＂ sign, nerve entering and exiting the tumor, fatencircling sign and fat-tail sign might provide significant information for the diagnosis.