颅内巨大动脉瘤的CT与MR诊断

目的：探讨ＣＴ和ＭＲ对颅内巨大动脉瘤的诊断价值。方法：８ 例颅内巨大动脉瘤病人进行了ＣＴ和ＭＲ检查，并经血管造影和手术证实。其中，男４ 例，女４ 例，年龄３４～７２岁，平均５４岁。临床上５例表现为颅内占位症状，３例为蛛网膜下腔出血症状。结果：５例动脉瘤起源于颈内动脉，２ 例起源于大脑中动脉，１例起源于椎基底动脉。ＣＴ和ＭＲ表现如下：（１）ＣＴ平扫病灶呈稍高密度圆形阴影，密度可均匀或不均匀，增强扫描病灶明显强化。（２）ＭＲ扫描显示残存瘤腔在Ｔ１ＷＩ及Ｔ２ＷＩ上均呈无信号区，周围为混合信号带。该信号带在Ｔ１ＷＩ上信号稍高于脑灰质，在Ｔ２ＷＩ上则稍低于脑灰质。增强扫描部分病例动脉瘤壁及混合信号带有强化表现。（３）动脉瘤破裂时，ＣＴ与ＭＲ可显示相应出血表现。结论：对颅内巨大动脉瘤的诊断，ＭＲ优于ＣＴ，尤其在显示瘤腔和血栓方面ＭＲ有独到之处

Giant Intracranial Aneurysms:CT and MR manifestations

Objective:To evaluate the value of CT and MR in diagnosis of giant intracranial aneurysm.Methods:Eight patients with giant intracranial aneurysm proved by surgery and angiography were studied by CT and MR.There were four men and four women,age ranging from 34 to 72 years(mean age 54).5 of them presented with intracranial mass effects,and 3 presented with subarachnoid hemorrhage.Results:The lesions originated from intercarotid artery in 5 patients,from cerebral middle artery in 2 patients and from basilar artery in 1 patient.The CT and MR manifestations of giant intractranial aneurysms were as follows:1) They were slightly hyperdense or hyperdense on plain CT scan,spheroidal in shape,and the density might be homogeneous or heterogeneous.After contrast injection,they enhanced markly;2)On MR scan,the residual patent portion of the aneurysmal lumen presented with signal avoid both on T 1-weighted image(T 1WI)and T 2 weighted image(T 2WI),surrounding it there were mixed intensity which was slightly hyperintense relative to gray matter on T 1WI and hypointense on T 2WI.The wall and mixed intensity portion of the aneurysm showed enhancement in some cases after contrast injection;3)When the aneurysm ruptured,there were intracranial hemorrhagic manifestations both on CT and MR.Conclusion:MR is superior to CT in diagnosis of giant intracranial aneurysm,especially in demonstrating the aneurysmal lumen and thrombi.