腹膜后神经鞘瘤的CT及磁共振影像表现分析

Analysis on the image performances of CT and MR on retroperitoneal schwannomas

目的:探讨腹膜后神经鞘瘤的CT及磁共振成像(MRI)表现,提高对其影像诊断的准确性。方法:选取医院收治的经手术病理证实的6例腹膜后神经鞘瘤患者,均行CT平扫+增强扫描检查,其中1例患者同时行MRI平扫+增强扫描检查,分析并总结其影像特征。结果:经CT及MRI检查,6例患者病灶均为单发且呈囊实性,CT平扫密度均低于同层面肌肉组织,密度不均。病灶内伴出血1例,细小钙化4例。病灶在MRI T_(1)加权成像(T_(1)WI)上呈低信号,T_(2)加权成像(T_(2)WI)出现中央稍低信号、周边高信号的“靶征”,弥散加权成像(DWI)序列病灶呈高信号,在表观弥散系数(ADC)图上病灶内部信号略低,边缘呈高信号。在CT及MRI增强图像上,6例患者均呈渐进性强化,其中5例动脉期呈轻度不均匀性强化,1例病灶内部可见小结节样明显强化影;1例MRI延迟期病灶内部呈均匀性明显强化,强化程度高于CT;4例病灶内部或病灶周围可见迂曲血管影。结论:腹膜后神经鞘瘤在CT及MRI上多表现为单发圆形或卵圆形的软组织肿块,边缘光滑、边界清晰,可伴钙化、出血、囊变,T_(2)WI“靶征”及不均匀性渐进性强化为特征性表现。

Objective:To investigate the performances of computed tomography(CT)and magnetic resonance imaging(MRI)on retroperitoneal schwannomas,so as to improve the accuracy of that for imaging diagnosis.Methods:A total of 6 patients with retroperitoneal schwannomas who were confirmed by surgical pathology in our hospital were collected,and all of them underwent CT plain scan plus enhancement scan.One of them underwent MRI plain scan plus enhancement scan at the same time.The image features of them were analyzed and summarized.Results:All of the 6 cases were single lesion,and the lesions of them appeared cystic-solid.The densities of CT plain scan of them were lower than those of the muscle tissue at the same layer,and the densities of them were uneven.One case with bleeding was within the lesion,and four cases with micro calcification were within the lesion.The lesions appeared low signals on the T_(1) weighted imaging(T_(1)WI)of MRI,and the T_(2) weighted imaging(T_(2)WI)occurred the“target sign”of lower signal at center and high signal at periphery,and the lesions of diffusion weighted imaging(DWI)sequence appeared high signals,and the signals inside the lesions on the apparent dispersion coefficient(ADC)picture were slightly low,and the edge of that appeared high signals.On the CT and MRI enhancement images,all 6 cases appeared progressive enhancement,and the arterial phases of 5 cases appeared mildly uneven enhancement,and the obvious enhancement shadow of like small nodule could be found within internal lesion of 1 case.The interior of 1 case appeared uniform and significant enhancement at MRI delay period,and the degree of enhancement of that was higher than that of CT.The tortuous vascular shadows could be found in the interior or surround of the lesions of 4 cases.Conclusion:The retroperitoneal schwannomas mostly appears soft tissue masses of single round or oval shape with smooth and clear edges,which accompany with calcification,bleeding and cystic degeneration.In addition,the T_(2)WI"Target sign"and uneven progressive enhancement are the characteristic manifestations of that.