外周良性神经纤维瘤与神经鞘瘤的MRI表现及鉴别诊断

摘要

Objective To investigate the MRI features of peripheral neurofibroma and schwannoma.Methods MRI of 18 patients with pathologically proven neurofibromas(7)and schwannomas(11)was retrospectively analyzed.Results All 18 tumors were solitary and located in the limbs,abdominal wall,supraclavicular muscles or fascia,and in the carotid sheath.The lesions were fusiform or round parallel to the neural trunk.Of 18 tumors,4 were T1 isointense and T2 hyperintense peripherally with T1 and T2 iso-hypointense centers and heterogeneous contrast enhancement.Eight lesions were T1 isointense and T2 hyperintense intermixed with patchy areas of T1 and T2 hypointensities and heterogeneous enhancement.Three schwannomas were cystic or cystic-solid with T1 hypointensity and T2 hyperintensity and homogeneous enhancement of cyst wall and septa.The remaining 3 tumors were T1 hypo-isointense and slightly T2 hyperintense with homogeneous enhancement.All 7 neurofibromas were not capsulated and located superficially in close relationship with nerves whereas all 11 schwannomas had complete or partial capsules and located deeper. Conclusion MRI characteristics can aid in differentiating neurofibromas from schwannomas.Neurofibromas are superficial,non-encapsulated and slightly T2 hyperintense.Schwannomas are located deeper,encapsulated and T2 hyperintense with necrosis and cystic degeneration.%目的：探讨外周良性神经纤维瘤与神经鞘瘤的MRI表现并分析两者的鉴别诊断。方法回顾性分析18例经手术病理证实的外周良性神经源性肿瘤的MRI特点，其中神经纤维瘤7例，神经鞘瘤11例。结果18例肿瘤均为单发，位于四肢、腹壁、锁骨上肌间隙或肌肉内以及颈动脉鞘周围，肿瘤呈梭形或类圆形，肿块长轴与神经干走行一致。全部肿瘤中出现靶征4例，表现为肿瘤边缘部分呈环形T1WI等信号、T2WI高信号，中央呈T1WI与T2WI等或低信号，增强后中央部分明显不均匀强化；8例肿瘤呈T1WI等信号，T2WI高信号，夹杂散在斑点片状T1WI、T2WI低信号，增强后明显不均匀强化；囊实性3例，表现为肿瘤内见多发T1WI低信号、T2WI高信号囊变区，增强扫描可见囊壁及分隔强化。3例肿瘤信号均匀，T1WI呈等或低信号，T2WI呈稍高信号，增强后均匀强化。7例神经纤维瘤均无包膜，病灶与周围组织界限不清，而11例神经鞘瘤均可见完整或部分包膜，病灶与周围组织界限清晰，并可见脂肪包绕。结论 MRI能准确显示外周良性神经纤维瘤与神经鞘瘤发生部位、形态、边缘及信号特点。神经纤维瘤无包膜，位置表浅，位于神经中央；神经鞘瘤有完整或部分包膜，位于深部或四肢屈侧较大的神经干周围，易出现坏死、囊变等改变，根据以上特点可以在术前对两者做出鉴别诊断。