恶性外周神经鞘膜瘤的MRI征象

MRI features of malignant peripheral nerve sheath tumor

目的 :观察恶性外周神经鞘膜瘤(Malignant peripheral nerve sheath tumor,MPNST)的MRI特殊征象和一般征象,提高本病的术前诊断准确率。方法:回顾性分析26例经病理证实的MPNST的MRI表现,其中20例行增强扫描。结果:(1)特殊征象:不典型"靶征"12例,9例位于四肢处,2例位于腰椎椎管内,1例位于髋关节周围软组织;"神经出入征"6例,均位于四肢坐骨神经走行区;"束征"6例,均位于四肢处。(2)动态强化方式及增强:动态强化呈Ⅱ型强化方式8例(40%),Ⅰ型强化方式10例(50%),对应表现为环形、片状、结节状不均匀强化;Ⅲ型强化方式2例(10%),对应表现为较均匀强化。(3)一般征象:12例形态不规则,边缘毛糙,14例形态较规则,边缘光滑;5例没有侵犯周围组织,21例侵犯周围组织;22例(84.6%)T_1WI表现为等或低信号,25例(96.2%)T_2WI主要表现为等或稍高或混杂高信号。结论 :MPNST的影像学表现具有一定的特征性,其中特殊征象不典型"靶征"、"神经出入征"、"束征"及Ⅰ、Ⅱ型动态强化方式对诊断有较大的帮助。

Objective： To explore the typical and common MRI features of malignant peripheral nerve sheath tumor（MPNST） in order to improve the preoperative diagnostic accuracy. Methods： A total of 26 patients MRI with MPNST confirmed by pathology were analyzed retrospectively（n=26, 20 patients underwent enhanced scan）. Results： ①Typical features： atypical“target sign”（n=12）, 9 cases in the limbs, 2 cases in lumbar spinal canal, 1 case in the soft tissues around the hip joint; “entering or exiting nerve sign”（n=6）, all were located in the region of the sciatic nerve; “fascicular sign”（n=6）, all were located in the limbs. ②Dynamic enhancement modes： 8 lesions（40%） showed type Ⅱ, 10 lesions（50%） showed type Ⅰ, the solid parts showed annular or patchy or nodular inhomogeneous enhancement; 2 lesions（10%） showed type Ⅲ enhancement, the solid parts showed homogeneous enhancement.③Common features： 2 cases showed irregular shape, rough edge, 14 cases showed regular shape, smooth edge; Five cases did not infiltrate to the soft tissue, 21 cases were infiltrative; Twenty-two cases（84.6%） T1WI showed equal or low signal, 25 cases（96.2%） T2WI showed equal ormixed high signal. Conclusion： There were typical MRI features in most of the MPNST, the special signs such as atypical “target sign”, “entering or exiting nerve sign”, “fascicular sign”, the type Ⅰ, type Ⅱ dynamic enhancemant modes have helpful to make the diagnosis.