下肢神经源性肿瘤的MRI表现

MR imaging of peripheral nerve tumors of the lower extremity

目的 评估下肢神经源性肿瘤的MR表现。方法 回顾性分析 5例经病理证实的下肢神经源性肿瘤的MR表现 ,其中 4例为神经鞘瘤 (3例良性 ,1例恶性 ) ,1例为恶性神经纤维瘤 ;肿瘤分别位于小腿 (2例 )、区 (1例 )、大腿 (1例 )和股区 (1例 )。 5例均行常规MR扫描 ,应用T1、T2 加权序列作轴面、冠状面和矢状面扫描 ,2例良性神经鞘瘤应用T1WSE作增强扫描。结果 在T1WI 2例良性神经鞘瘤呈等信号强度 ,1例良性神经鞘瘤、1例恶性神经鞘瘤和 1例恶性神经纤维瘤呈不均质的低 中等信号强度。在T2 WI 5例肿瘤均呈不均质高信号。 2例神经鞘瘤可见靶征 ,表现为瘤体中央为低信号区 ,其周围为高信号区 ,于T2 WI显示清楚。结论 MRI有利于明确肿瘤的位置和范围 ,以及外科治疗计划的制定。靶征对周围神经源性肿瘤的诊断是 1种有价值的征象。

Objective To evaluate MR imaging of peripheral nerve tumors of the lower extremity. Methods MR imaging of peripheral nerve tumors of the lower extremity in five cases proved by surgery and pathology were retrospectively reviewed. In all patients, routine scanning was performed in axial, coronal, and sagittal planes, including T 1-weighted and T 2-weighted images. In two patients (schwannomas), T 1WI were obtained following intravenous injection of Gd-DTPA. Results There were four schwannomas (three benign and one malignant) and one malignant neurofibroma. Tumors arose at the following sites: leg ( n =2), popliteal region ( n =1), thigh ( n =1), and femoral region ( n =1). On T 1WI, tumors generally showed isointensity (two benign schwannomas) or lower-medium signal intensity to adjacent muscle with minimal inhomogeneity (one benign schwannoma, one malignant schwannoma, and one malignant neurofibroma). On T 2WI, tumors demonstrated inhomogeneous high signal intensity in all five patients. The target sign with peripheral hyperintense rim and central low intensity was see in two benign schwannomas on T 2WI. Conclusion MRI is useful in defining the location and extent of a lesion and in assisting the surgical planning. The target pattern appears to be a useful sign in the diagnosis of peripheral nerve tumors.