Sella Turcica and Parasellar Region(蝶鞍和鞍旁区病变影像诊断).pptVIP

In over 50% of cases craniopharyngiomas have a pathognomonic appearance. On these unenhanced and enhanced T1-weighted sagittal images, a compressed pituitary gland can be identified. There is a large intrasellar and suprasellar mass with cystic and enhancing components as well as calcifications. These findings in a child are virtually pathognomonic for craniopharyngioma (perhaps with only a dermoid in the differential diagnosis). Coronal images of the same mass. And axial images. Unenhanced CT shows the calcifications more clearly. After intravenous contrast the total extent of the lesion and its cystic components are much less evident. The most common intracranial tumor in adults is the meningioma with 20% of occurring at the skull base. This is an autopsy specimen with the brain removed, showing a meningioma sitting on the diaphragma sellae. Meningiomas are almost always solid lesions, sometimes with a cyst on the edge. They can lift up the arachnoid a little bit and enhance uniformly as a general rule. Ⅵ Meningioma Notice the spread of the lesion along the meninges. The epicentre of the lesion is above the sella. ● On the top-left unenhanced and enhanced CT-images, the main differential diagnosis of the enhancing mass would include meningioma, pituitary adenoma and an aneurysm. ● The post-constrast MR-image on the top-right rules out an aneurysm as a possible diagnosis (no flow void), but on axial images a pituitary adenoma and meningioma are still difficult to differentiate. On the coronal images (T1 and T1-postcontrast), a compressed pituitary gland can be identified at the bottom of the sella turcica. Above it lies a large mass, partially intrasellar and partially suprasellar. Although the diaphragma sellae can not be identified on these images, it is probably a suprasellar mass growing downwards. When pituitary macroadenomas get this size they usually have areas of hemorrhage or necrosis - in mengiomas this is less often the case. Meningioma.