【正文】 ent. With a hydrocephalus. These findings are very specific for a Craniopharyngeoma. On the left NECT and enhanced CTimages of a 33yearold female with severe headache (worse in the .), reduction in visual acuity and visual fields and papilledema. Continue with the MR images. Notice the normal inferiorly displaced pituitary gland. This means it is not a macroadenoma. The diagnosis is again a Craniopharyngioma. The differential diagnosis would include an astrocytoma and a meningioma. Cerebellopontine angle A 52yearold male with hearing loss on the right. The images show an unusual cystic mass with enhancing septations. There is also some enhancement within the internal acoustic canal. Based on the images the most likely diagnosis would be a cystic schwannoma, but this happened to be an unmon, cystic presentation of a Meningioma. On the left a tumor located in the pineal region. Based on these images the differential diagnosis would include: Meningioma Pineocytoma Germ Cell Tumor This happened to be a meningioma. On the left are typical images of a ruptured pineal region dermoid. ? On the left images of a 40y/o female with blurred vision and memory decay for one month， graduall stoit ， nausea and vomiting . ? This is an Oligoastrocytoma Grade 3. On the left images of a 12 y/o male with upward gaze paralysis. There is a tumor located in the pineal region. The tumor contains calcifications. There is homogeneous enhancement, which is mon for a tumor in the pineal region (discussed above). Based on the age of the patient, the location and the tumor characteristics, this is most likely a Germinoma. Intraventricular On the left a tumor located in the 3rd ventricle. The tumor contains calcifications. The diagnosis is a Giant cell astrocytoma. 4th ventricle In children tumors in the 4th ventricle are very mon. Astrocytomas are the most mon followed by medulloblastomas (or PNETMB), ependymomas and brainstem gliomas with a dorsal exophytic ponent. In adults tumors in the 4th ventricle are unmon. Metastases are most frequently seen, followed by hemangioblastomas, choroid plexus papillomas and dermoid and epidermoid cysts. Medulloblastoma Many nontumorous lesions can mimic a brain tumor. Abscesses can mimic metastases. Multiple sclerosis can present with a masslike lesion with enhancement, also known as tumefactive multiple sclerosis. In the parasellar region one should always consider the possibility of a aneurysm. Tumor Mimics Infections and vascular lesions can also mimic a CNS tumor. Thanks for your attention ! 。s are hyperintense on T2WI. PNET typically has a high nuclearcytoplasmic ratio，which mostly located in the region of the 4th ventricle, another less mon location is in the region of the pineal gland. Mucinous metastases often with calcifications. Meningiomas ： isoSI . High SI on T2WI if they contain a lot of water. Low SI on T2WI if they are very dense and hypercellular or when they contain calcifications. High intensity on DWI indicates restriction of the ability of water protons to diffuse extracellularly. Restricted diffusion is seen in abscesses, epidermoid cysts and acute infarction (due to cytotoxic edema). In cerebral abscesses the diffusion is probably restricted due to the viscosity of pus, resulting in a high signal on DWI. In most tumors there is no restricted diffusion even in necrotic or cystic ponents. This results in a normal, low signal on DWI. Diffusion weighted imaging Perfusion imaging can play an impor