Brain edema develops in approximately 50%of meningiomas Their preferential locations are as follows:parasagittal or attached to the sagittal sinus (25%);the convexity (2%),sphenoid wings(%)parasellar (5-10%);olfactory grooves (210%);Ten percent are infratentorial and arise from the petrous bone in the cerebellopontine angle,the clivus,the tentorium Rarely meningiomas are intraventricular,or arise from the optic nerve sheath CT shows a well marginated oval or lobulated mass,attached to the dura at an obtuse angle.Most lesions are homogeneously hyperdense,some isodense and a few hypodense Calcifications are diffuse or focal Marked homogeneous enhancement Pituitary adenoma 15min Pituitary adenoma is tumor arising from the cells of the pituitary gland A tumor of less than 10mm in diameter is called a microadenoma and is usually confined within the sella turcica A macroadenoma is a tumor of more than 10 mm in diameter and usually extends beyond the confines of the sella turcica a.upward toward the chiasm and hypothalamus b.downward toward the sphenoid sinus c.laterally toward the cavemous sinuses Pituitary adenomas are usually benign tumors Pituitary carcinomas are very rare Metastases from pulmonary or breast tumors may grow within th pituitary gland A similar effect is seen with MR:usually only TI-weighted sequences are used and the microadenoma is more evident following jection since it appears hypointense within an hyperintense pituitary.Enhancement may be inhomogeneous. ⚫ Brain edema develops in approximately 50% of meningiomas Their preferential locations are as follows: parasagittal or attached to t he sagittal sinus (25%); the convexity (20%); sphenoid wings (15~20%); parasellar (5~10%); olfactory grooves (2~10%) ; Ten percent are infratentorial and arise from the petrous bone in the cerebellopontine angle, the clivus, the tentorium ; Rarely meningiomas are intraventricular, or arise from the optic nerve sheath ⚫ CT shows a well marginated oval or lobulated mass, attached to the dura at an obtuse angle. Most lesions are homogeneously hyperdense, some isodense and a few hypodense ⚫ Calcifications are diffuse or focal ⚫ Marked homogeneous enhancement Pituitary adenoma ⚫ Pituitary adenoma is tumor arising from the cells of the pituitary gland A tumor of less than 10mm in diameter is called a microadenoma and is usually confined within the sella turcica A macroadenoma is a tumor of more than 10 mm in diameter and usually extends beyond the confines of the sella turcica a. upward toward the chiasm and hypothalamus b.downward toward the sphenoid sinus c.laterally toward the cavernous sinuses ⚫ Pituitary adenomas are usually benign tumors ⚫ Pituitary carcinomas are very rare ⚫ Metastases from pulmonary or breast tumors may grow within the pituitary gland A similar effect is seen with MR; usually only T1 -weighted sequences are used and the microadenoma is more evident following gadolinium injection since it appears hypointense within an hyperintense pituitary. Enhancement may be inhomogeneous. 15min