磁共振增强扫描对颅后窝占位性病变 的诊断价值

目的 评价增强扫描对颅后窝占位性病变定性诊断及术后随访的价值。方法 回顾性分析38例颅后窝占位性病变的MRI平扫及增强表现。全部病例均经手术病理及临床证实,其中星形细胞瘤8例。髓骨细胞瘤3例。血管母细胞瘤4例。转移瘤5例,脑膜瘤9例,脑脓肿2例,表皮样囊肿3例。蛛网膜囊肿4例。结果 血管母细胞瘤呈大囊小结节型。壁结节显著均匀强化,囊壁囊液不强化;髓母细胞瘤实质强化较明显,内部囊变区较小;星形细胞瘤可呈实质性或囊实性,强化表现复杂;转移瘤及脑脓肿强化表现相似,可结合病史加以鉴别;脑膜瘤明显强化,并可显示：脑膜尾征“,表皮样囊肿和蛛网膜囊肿不强化,9例患者术后进行了11次复查,1例诊断肿瘤残留复发,8例可见不同程度的术后改变。结论 MRI增强扫描能对大多数颅后窝占位性病变进行定性诊断,对临床治疗及术后随访具有较高的指导意义。

Diagnosis of Posterior Fossa Masses with Contrast-Enhanced MRI

Objective To evaluate Gd DTPA enhanced MRI in the diagnosis of posterior fossa masses and follow up survey after operation. Methods MRI manifestations of 38 cases with occupied posterior fossa masses were reviewed.All cases were proved pathologically and clinically,and studied with Gd DTPA,including astrocytoma in 8 cases,medulloblastoma in 3 cases,hemangioblastoma in 4 cases,metastatic tumor in 5 cases,meningioma in 9 cases,abscess in 2 cases,epidermoid cyst in 3 cases and arachnoid cyst in 4 cases. Results Imaging findings of posterior fossa masses were complicated.The hemangioblastomas had big cyst and small nodule.The nodules were homogeneous enhanced after injection of Gd DTPA,and the cysts were not enhanced.The medulloblastomas were obviously enhanced,and cystic areas were small.The astrocytoma was materiality or cyst and solid.And it was heterogeneous after injection of Gd DTPA.The metastatic tumor and the abscess were similar after enhanced,we could differentiate them by the disease history.The meningiomas were enhanced obviously,and could show the "meninges tail".The epidermis kind cyst and the arachnoid cyst were not enhanced.Nine cases had 11 reexamination after operation,one case had postoperative recurrence and 8 cases had changes of operation. Conclusion Contrast enhanced MRI can diagnose most of posterior fossa masses qualitatively.