臂丛神经鞘瘤的MRI表现与手术对照研究

目的:评价臂丛神经鞘瘤的MRI表现,并与手术所见对照分析,以期对临床诊治有所裨益。材料和方法:经手术和病理证实的36例臂丛神经鞘瘤,术前均行MRI检查。所有患者MRI检查序列包括轴位T2WI(STIR),增强前后横断面、斜矢状面和冠状面T1WI(增强后扫描加脂肪抑制),部分病例增强前加扫冠状面T2WI。2名有经验的放射科医师分别对病变部位、肿块大小、边界、信号、强化及范围作出判断。病变的定位及MRI不同序列中的特征与手术和病理表现行对照研究。结果:臂丛神经的根、干及分支在MRI所有序列中均表现为线状低信号影。36例臂丛神经鞘瘤平均大小为4.9cm(3.0～6.8cm),均表现为沿臂丛神经根生长的肿块。30例表现为边界清楚的纺锤形或长圆形肿块。MRI信号特点:16例表现为均匀的T1WI低或等信号(与肌肉相比),T2WI高信号,增强后中等度强化;20例T1WI呈低信号,T2WI呈不均匀高信号,内见低信号区,所谓的“靶征”,增强后明显强化。所有患者的显微外科手术均遵循肿块内容物的摘除,包膜的剥离与神经的保护相结合的原则。结论:根据臂丛神经鞘瘤的特征性部位和形态学表现以及MRI信号特点,能对本病作出诊断、鉴别诊断及预后判断。该病的典型表现有利于术前作出正确诊断,显微外科手术有利于保护有关神经。

MRI Features of Schwannomas of the Brachial Plexus Correlated with the Surgical Findings

Purpose:To investigate the value of MRI in the diagnosis of schwannomas of the brachial plexus corre-lated with the surgical findings.Materials and Methods:Thirty six consecutive patients with schwan-nomas of the brachial plexus,proven surgically and pathologically,referred for MR imaging with a1.5-T unit.All patients underwent axial T 2 -weighted imaging,pre-and post-contrast T 1 -weighted axial,oblique sagittal and coronal imaging covering the axilla to the middle of the neck.The MRI findings were evaluated independently by two radiologists for the locations of masses,size,margin,signal intensity,contrast enhancement,and extent of the lesions.The locations and characteristics of the lesions on dif-ferent types of MR sequences were described with surgical correlation.Results:The roots,trunks,and various divisions of the brachial plexus appear as linear structures with low signal intensity on MR images obtained with all sequences.All patients had large schwannomas(mean size4.9cm,ranged from3.0to6.8cm in diameter)presenting as masses along a brachial plexus nerve root,explored by MRI.Most of the masses(n=30)exhibit spindle or longish shape with well-defined margins.16cases appears as ho-mogeneous hypo-or isointense to muscle in T 1 -,hyperintense in T 2 -weighted images,and moderate contrast enhancement after administration of contrast media.20lesions are hypo-isointense to muscle on T 1 -weighted images and heterogeneous hyperintense on T 2 -weighted images which may have central areas with low signal intensity,the so-called target sign,and enhance intensely after administration of gadolinium-based contrast material.All patients have been operated upon using microsurgical tech-nique:enucleation of the tumor content,piecemal removal of the capsule,identification and preservation of the neural elements were the main goals of the operation in all cases.Conclusion:The locations, morphologic features and MR signal characteristics are useful in detecting schwannomas of the brachial plexus and can help improve ability in differentiating diagnosis and evaluating prognosis.The microsur-gical treatment with preservation of the neural structures results in good outcome without recurrences.