椎管内蛛网膜囊肿的影像诊断

Imaging Diagnosis of Spinal Arachnoid Cyst

目的 分析椎管内蛛网膜囊肿的X线平片、CT及MRI表现 ,以提高对本病的认识。资料与方法 回顾性分析 2 9例经手术病理证实的椎管内蛛网膜囊肿影像特征并评价不同影像方法对该病的诊断价值 ,X线平片及MRI检查 2 9例 ,9例行CT检查。结果 髓外硬脊膜下及较小的硬脊膜外蛛网膜囊肿X线平片无异常表现。较大的硬脊膜外蛛网膜囊肿X线平片、CT及MRI均显示椎管及椎间孔呈对称性扩大。CT及MRI显示囊肿的密度或信号与脑脊液类似 ,并能显示伸出椎间孔外的硬脊膜外蛛网膜囊肿有“分叉征”。只有MRI能正确显示囊肿在椎管内的位置 ,并能显示与蛛网膜下腔相通的裂孔平面的囊肿腔内有“脑脊液喷射征”。结论 MRI对大多数椎管内蛛网膜囊肿具有定位和定性诊断价值 ,并可判断硬脊膜外蛛网膜囊肿与蛛网膜下腔相通的裂孔位置。CT对该病具有一定诊断价值 。

Objective To analyze radiographic, CT and MRI findings of spinal arachnoid cyst, to make a further understanding of the disease.Materials and Methods Imaging features in 29 patients with pathologically proved spinal arachnoid cyst were retrospectively analyzed. Both MRI and radiography were performed in all 29 cases, of which additional CT scan was carried out in 9. Results In patients with subdural or small extradural arachnoid cyst, no abnormality was found on plain radiographs. In cases with larger extradural arachnoid cyst, symmetrical widening of the spinal canal and intervertebral foramen was demonstrated on plain radiograph, CT and MRI. On CT and MRI, the cyst carried the same density and signal intensity as the cerebrospinal fluid (CSF), and 'bifurcate' sign producing by the extradural arachnoid cyst that extended beyond the intervertebral foramen could also be seen. MRI could precisely identify the lesion's site and show 'CSF ejection' sign.Conclusion For most cases, MRI plays an important role in making localization and qualitative diagnosis of spinal arachnoid cyst, as well as in identifying the location of the orifice connecting the cyst and subarachnoid cavity. CT scanning has certain diagnostic value, while plain radiograph shows limited value in the diagnosis of the disease.