1、,Ectopic pituitary gland. Note the high signal intensity in median eminence and the absent normal posterior pituitary hyperintensity.,Sagittal contrast-enhanced T1-weighted MRI shows a nonenhancing, hypointense lesion. Pituitary adenomas are most commonly hypointense on T1-weighted MRIs and hyperint
2、ense on T2-weighted MRIs.,Empty sella. Note the cerebrospinal fluid signal intensity in the herniated arachnoid space through the diaphragma sellae sella (which is partially filled with cerebrospinal fluid).,A 37-year-old woman presented with pituitary apoplexy. Note the high signal intensity in the
3、 pituitary gland secondary to hemorrhage on this T1-weighted MRI.,Sagittal T1-weighted MRI shows hemorrhage in a huge pituitary adenoma.,Coronal T1-weighted MRI shows a nonenhancing pituitary macroadenoma invading the left cavernous sinus (arrow).,Sagittal T2-weighted MRI shows a hyperintense cystic
4、 lesion above the pituitary gland due to a Rathke pouch cyst in the region of the pars intermedia.,Coronal T2-weighted MRI shows a large partially cystic craniopharyngioma that is causing obstructive ventriculomegaly.,Coronal fluid-attenuated inversion recovery (FLAIR) MRI of the brain shows an aneu
5、rysm of the intracranial carotid artery that is compressing the optic chiasm.,T1-weighted MRI shows a pearly, subarachnoid epidermoid cyst and high signal intensity.,Axial contrast-enhanced T1-weighted MRIs show an epidermoid cyst. Note the low signal intensity in the tumor along crevices of the sub
6、arachnoid space.,Sagittal T1-weighted image of the brain shows a hypothalamic hamartoma. Note the nonenhancing, small hypothalamic lesion with signal intensity similar to that of the gray matter in the region of the hypothalamus.,Axial contrast-enhanced T1-weighted MRIs show a metastasis to the sphe
7、noid bone and the cavernous sinus from a primary site in the colon.,T1-weighted sagittal image obtained before contrast enhancement depicts a well-marginated sellar mass, a Rathke cleft cyst, extending into the suprasellar cistern. Note that the mass has homogeneous high signal intensity relative to
8、 the brain parenchyma.,T2-weighted axial image shows the mass, a Rathke cleft cyst, is isointense relative to the cortex. (This image was obtained in the same patient as in the previous image.),T1-weighted sagittal image obtained before contrast enhancement demonstrates a well-defined Rathke cleft c
9、yst in the sella that is isointense relative to the cerebrospinal fluid. Note the normal high signal intensity in the posterior pituitary, which is draped over the dorsal aspect of the cyst.,The Rathke cleft cyst is isointense relative to the cerebrospinal fluid, as shown on this coronal proton dens
10、ityweighted image obtained through the sellar region. The mass effect on the optic chiasm is well depicted.,T1-weighted coronal image shows a subcentimeter Rathke cleft cyst in the central part of the sella. The cyst is slightly hyperintense relative to cerebrospinal fluid.,Coronal T1-weighted contr
11、ast-enhanced image shows a nonenhancing hypointense Rathke cleft cyst adjacent to the homogeneously enhancing pituitary gland.,On this T2-weighted coronal image, the Rathke cleft cyst is isointense relative to cerebrospinal fluid.,The variable appearance of Rathke cleft cyst is readily demonstrated
12、on this image. A large, lobulated, and well-marginated cystic mass is centered in the sella turcica, extending both in a suprasellar plane and into the sphenoid and ethmoid sinus regions. This lesion is hyperintense relative to cerebrospinal fluid on this T1-weighted sagittal image; this signal inte
13、nsity likely reflects its high protein content.,The Rathke cleft cyst is hyperintense relative to cerebrospinal fluid on this axial proton densityweighted image. Note expansion of the sella with lateral deviation of the mildly effaced but patent cavernous internal carotid arteries.,T2-weighed axial image demonstrates a large hyperintense Rathke cleft cyst.,T1-weighted axial gadolinium-enhanced image demonstrates no enhancement of the Rathke cleft cyst.,
