脑包虫病的MRI表现及诊断

MRI f＇mdings and diagnosis of brain echinococcus

目的分析脑包虫病的MRI特征性表现。方法回顾性分析18例经手术病理证实脑包虫病患者的MRI表现，总结脑包虫病的MRI诊断与鉴别诊断要点。结果18例脑包虫病患者中囊性包虫病和泡型包虫病各9例。囊性包虫病表现为脑内大小不等的圆形长T1、长T2信号病灶，内部信号均匀一致，液体衰减反转回复（FLAIR）序列扫描其内囊液信号可被抑制；DWI序列病灶为低信号；6例病灶周围无水肿带，3例破裂包虫囊肿病灶周围有水肿带；6例病灶见囊壁显示，3例病灶囊壁显示不明显；增强扫描3例破裂包虫囊肿有环形强化，6例病灶无强化；泡型包虫病表现为脑内多发等T1、短T2簇状异常信号，病灶周围通常有类似脑肿瘤样的水肿带。病灶T2WI信号似“煤炭样”黑色的低信号，内见无数密集稍高信号的小囊泡影，小囊泡直径约1—10mm为其特征性表现。DWI序列病灶为低信号；Gd—DTPA增强扫描后病灶均见不规则的异常环形强化。2例脑灌注成像病变为低灌注改变。结论MRI以多方位、多参数成像的优势显示脑包虫更准确，术前诊断率更高，对临床诊治具有重要意义。

Objective To study the characteristic findings of brain echinococcosis on MRI. Methods The MRI findings of 18 patients with pathologically confirmed brain echinococcosis were retrospectively reviewed. Results Among the patients, there were 9 cases of cystic echinococcosis and 9 cases of alveolar echinococcosis. In cystic echinocoecosis, MRI revealed homogeneously hypointensity on T1WI and hyperintensity on T2WI, while it showed low signal intensity inside the cysts on FLAIR and DWI. In 6 cases of cystic echinococcosis, no edema was detected surrounding the lesions, while edema resulting from cyst rupture was found in 3 cases. The cystic walls were visible in 6 cases, obscure in 3 cases. The ruptured hydatid cysts in 3 cases showed slight ring enhancement. Alveolar echinococcosis appeared as multiple lesions with isointensity on T1WI and hypointensity on T2 WI, surrounded by vasogenic edema. The ＂charcoal-like＂ hypointensity and innumerous hyperintense bubbles of 1-10 mm in diameter inside the lesions on T2-weighted MR images were characteristic for lesions of alveolar echinococcosis. The lesions revealed hypointensity on DWI and showed irregular ring enhancement after injection of Gd-DTPA. Perfusion-weighted MR imaging revealed low relative cerebral blood volume. Conclusion MRI can demonstrate lesions of brain echinococcosis accurately due to its advantages of multiorientation and multiparameter. It is clinically valuable.