脉络膜裂蛛网膜囊肿的CT、MRI诊断

CT and MRI Diagnosis of Arachnoid Cyst in Choroidal Fissure

目的 探讨脉络膜裂蛛网膜囊肿的CT与MRI表现。资料与方法 回顾性分析经CT和MRI诊断为脉络膜裂蛛网膜囊肿 2 3例的临床及影像学资料。CT轴位扫描 18例 ,其中增强扫描 4例 ,CT冠状位扫描 2例 ;MRI检查14例 ;单独MRI检查 5例。结果 2 3例病灶均位于两侧脉络膜裂区 ,右侧 15例 ,左侧 8例 ,均为单发病灶 ,最大者2 2mm× 2 8mm ,最小者直径 5mm。CT轴位像病灶呈长卵圆形、圆形 ,与环池相连 14例 ,CT值 6～ 2 0HU ,平均为 11.4HU。MRI冠状位像呈“双凸透镜”形、卵圆形 ,矢状位像呈卵圆形、“箭头样”表现 ;均呈长T1长T2 信号 ,FLAIR序列示囊肿呈低信号。CT、MRI增强扫描均无强化。其中CT首次诊断而误诊为其他疾病 10例 ,MRI 2例。结论 脉络膜裂蛛网膜囊肿在CT和MRI上的密度 /信号与其他部位的蛛网膜囊肿无差异 ,认真分析脉络膜裂解剖 ,多可明确诊断 。

Objective To study CT and MRI findings of arachnoid cyst in choroidal fissure. Materials and Methods23 cases of arachnoid cyst in choroidal fissure proved by CT and MRI were analyzed. Axis CT scanning was employed in 18 cases, coronal CT scanning in 2 cases, additional enhancd CT scanning in 4 cases. Additional MRI was performed in 14 cases and MRI alone in 5. Results All lesions of 23 cases were located at the area of choroidal fissure, including 15 cases in right and 8 in left. All was single lesion with the size of the biggest 22mm×28mm and the smallest 5mm in diameter. On axial CT scans the lesion appeared ellipsoid or round in shape linked with ambient cistena in 14 cases, and was 6～26HU with average 11.4HU. On MRI, the lesion appeared double convex lens or egg in shape in coronal section and round or arrow head like in shape in sagittal section. They all showed hypointensity on T 1WI and hyperintensity on T 2WI, but cyst appeared hypointensity in FLAIR sequence. All lesions were not enhanced on enhanced CT and MRI. Conclusion Arachnoid cyst in choroidal fissure has the same density or singal on CT or MRI as ones in other places. They can be diagnosed by CT or MRI by analyzing the anatomy of choroidal fissure, but MRI is quite good.