History: A young man presents with a headache.
病史：年轻男性，头痛。
MR image is shown below. MR图像如下所示。
Additional images
T2-weighted and fat-suppressed contrast-enhanced T1-weighted images are shown below.
T2WI及T1WI压脂增强图像如下所示。
Findings
A cystic structure is seen in the splenium of the corpus callosum with a small internal nodule and smooth rim enhancement. There is an additional small cyst with internal signal consistent with fluid in the anterior horn of the left lateral ventricle.
影像表现：胼胝体压部见一囊性结构，内见一小壁结节，增强扫描壁环形强化，表面光滑。左侧侧脑室前角另见一小液性囊性灶。
Differential diagnosis
- Neurocysticercosis
- Abscesses
- Metastatic disease
鉴别诊断：
- 脑囊虫病
- 脑脓肿
- 转移瘤
Diagnosis: Neurocysticercosis (NCC), colloidal vesicular stage
诊断：脑囊虫病（NCC），胶样囊泡期
Key points
Neurocysticercosis (NCC)
Neurocysticercosis is a parasitic infection of the central nervous system is caused by the pork tapeworm Taenia solium.
Highest incidence is in Latin America.
Depending on location of the infection, patients may present with headache, seizures, hydrocephalus, etc.
Symptoms are caused by the immune reaction to NCC, not the lesions themselves.
Typically occur in subarachnoid spaces, ventricles/cisterns, and at the gray/white matter interface.
Variable-size cysts may be seen with or without rim enhancement and a small central nodule (scolex).
Four stages of infection:
- Vesicular: Viable larva; smooth-walled cyst with central scolex
- Colloidal vesicular: Degenerating larva; rim-enhancing cyst and marked surrounding edema
- Granular nodular: Healing stage; mild edema and rim enhancement
- Nodular calcified: Healed stage; small, involuted cyst with or without calcifications
Metastatic disease is far more common and must always be considered in the differential.
Large, complex cysts with edema may mimic a neoplasm.
知识点
脑囊虫病是猪肉绦虫所致的一种中枢神经系统寄生虫感染疾病。
拉美地区发病率较高。
因病变发病部位不同，患者可表现为头痛、癫痫、脑积水等。
症状由对脑囊虫病的免疫反应所致，与病变本身无关。
典型发病部位：蛛网膜下腔、脑室/脑池、灰白质交界处。
表现为大小不等囊肿，有或无环形强化及小中心结节（头节）。
感染过程分为四期：
- 囊泡期：为存活的幼虫，囊壁光滑，内可见头节；
- 胶样囊泡期：为退变的幼虫，环形强化囊肿，明显周围水肿；
- 颗粒结节期：逐步愈合期，轻度周围水肿，环形强化；
- 钙化结节期：已愈合期，小复杂囊肿，有或无钙化。
转移瘤更加常见，鉴别诊断必须考虑。
体积大的复杂囊肿并周围水肿，表现可与脑肿瘤近似。
本例为胶样囊泡期NCC，T2WI示胼胝体压部后缘病灶周围可见片状水肿带。
根据囊虫寄宿的部位不同大致分为：
- 脑实质型
- 脑室型
- 蛛网膜下腔型
- 混合型
以脑实质型较多见；脑室型和蛛网膜下腔型可形成阻塞性脑积水、脑膜粘连。
CT平扫（A~C）示双侧大脑半球多发散在小圆形低密度影，其内可见小结节状高密度，为囊虫头节（↑），无占位效应，周围脑组织无水肿。
女性，24岁，双侧幕上大脑半球皮层下多发圆形异常信号影。T1WI（B）为低信号，内可见等信号头节，T2WI（B）为明亮高信号，内可见点状低信号，FLAIR（C）为低信号，内可见点状高信号；增强扫描（D）病变呈环形强化。周围无明显水肿。
CT平扫（A、B）左侧额叶皮层下见类圆形低密度影，幕上半球散在小点、片状钙化影；CT增强扫描（C、D）无明显强化。部分病灶位于脑室内室管膜，并幕上脑积水。