MR Imaging of the ellar and Juxtasellar

.... S MR Imaging of the ellar and Juxtasellar. 1,: Regions DavidE.Jobnsen, MD. William W. Woodruff MD Ira S. Allen, MD PeterJ. Cera, MD George R. Funkbouser, MD Linda L. Coleman, MD. Multiplanar capability and superior tissue contrast differentiation ren- der magnetic resonance (MR) imaging the preferred method for exam- : ining patients with pituitary axis dysfunction or visual field deficits. In a review of 131 sellar or juxtasellar abnormalities, 76% were common lesions with distinctive features that helped establish their diagnosis: macroadenoma (n = 51), microadenoma (n = 20), meningioma (n = 14), craniopharyngioma (n = 10), and aneurysm (n = 5). On Ti-weighted images, microadenomas were usually hypointense relative to normal pituitary gland, and macroadenomas and meningiomas were isointense relative to gray matter. Both microadenomas and meningiomas were more conspicuous immediately after contrast material administration. Craniopharyngiomas were the most heterogeneous of all the sellar lesions due to their cystic and solid components. MR images of aneurysms showed flow void and heterogeneous increased signal intensity in areas of slower turbulent flow. Other characteristics such as extrasellar versus intrasellar location, nature of contrast material enhancement, the presence of cystic components, and clinical findings permitted differentiation among less common lesions, including granulomatous disease, metastases, chiasmatic glioma, arachnoid cyst, hypothalamic glioma, schwannoma, germinoma, epidermoid, Rathke cyst, chordoma, chondrosarcoma, colloid cyst, and hamartoma. Abbreviations: ACTH = adrenocorticotrophic hormone, H-E = hematoxylin.eosin, TE = echo time, TR = repetition time Index terms: Pituitary, diseases, 145.22, 145.23 #{149} Pituitary, MR studies, 145.1214 #{149} Pituitary, neoplasms, 145.30 #{149} Sella turcica, MRstudies, 122.1214 RadloGraphics 1991; 11:727-758 I From the Departments ofradiology (D.EJ., W.W.W., G.R.F., L.L.C.) and Pathology (ISA., PJ.C.), Geisinger Medical Center, Danville, Pa. From the 1990 RSNA scientific assembly. Received February 20, 1991; revision requested April 12 and received May 24; acceptedjune 4. Address reprint requests to D.E.J., Danville Radiologists, 125 Executive Dr, Suite D, Danville, VA 24541. C RSNA, 1991 727

Table 1 Diagnoses for 131 Sellar and Juxtasdilar Abnormalities Diagnosis No. of Cases* Pituitary adenoma 71 (54.2) Microadenomas 20... Macroadenomas 5 1.. Meningioma 14 (10.7) Craniopharyngioma 10 (7.6) Aneurysm 5 (3.8) Granulomatous diseaset 4 (3 1) Metastatic disease 4 (3.1) Chiasmatic glioma 3 (2.3) Arachnoid cyst 3 (2.3) Hypothalamic glioma 3 (2.3) Epidermoid 3 (2.3) Schwannoma 2 (1.5) Hypothalamic germinoma 2 (1.5) Rathkecleftcyst 2 (1.5) Chordoma 2 (1.5) Chondrosarcoma 1 (0.8) Colloid cyst 1 (0.8) Hypothalamic hamartoma 1 (0.8) * Numbers in parentheses are percentages. t Includes three cases of tuberculosis and one case of sarcoidosis.. INTRODUCTION Patients with symptoms and signs of pituitary axis dysfunction or visual field deficits are frequently referred for diagnostic imaging procedures. Magnetic resonance (MR) imaging has virtually supplanted other imaging techniques (computed tomography [CT], angiography, tomography) as the modality of choice for evaluation of the sellar and juxtasellar regions. It provides multiplanar images with superior tissue contrast differentiation, and it is noninvasive. We retrospectively analyzed MR examinations of 13 1 cases of sellar or juxtasellar abnormalities that were pathologically or medicatty proved (Table 1). The studies were performed with a 1.5-T imaging unit (Signa; GE Medical Systems, Milwaukee) and generally consisted of parasagittal and coronal Tiweighted sequences (repetition time [FR] of 500 msec and echo time [TE] of 20 msec, 256 x 256 matrix, four excitations, 18-cm field ofview, 3-mm-thick sections with a 1-mm gap). Enhanced coronal Ti-weighted images were routinely acquired with gadopentetate dimeglumine after it became commercially available. A double-echo T2-weighted sequence (TR = 2,000 msec and TE = 30-90 728 U RadioGrapbics U Johnsen Ct al

a. b. Figure 2. (a) Drawing illustrates normal anatomy of the sella turcica and juxtasellar region in the parasagittal plane. A = adenohypophysis, B = neurohypophysis, C = infundibulum, D = optic chiasm, E = tuber cinereum, F = anterior third ventricle, G = mamillary bodies, H = interpeduncular cistern, I = prepontine cistern,j = clivus, K = sphenoid sinus. (b) Parasagittal Ti-weighted MR image shows the normal anatomic structures: adenohypophysis (thick white arrow), neurohypophysis (open arrow), infundibulum (thin white arrow), and optic chiasm (black arrow). glandlike spaces representing remnants of the Rathke cleft. U ANATOMY In the sagittal plane (Fig 2), the sella turcica is a midline, shallow depression in the posterior sphenoid bone that contains the pituitary gland. The floor of the sella turcica is variable in appearance, depending largely on the degree of aeration of the underlying sphenoid sinus. The cortical bone and air-filled sinus may merge imperceptibly on MR images. The dorsalmost aspect of the sphenoid bone descends to form the clivus. The roof of the sella turcica is formed by a dural reflection, the diaphragma sellae. This thin membrane is inconsistently visualized on MR images but is best seen on long TR/short TE images (1). The two lobes of the pituitary gland are embryologically, physiologically, and anatomically distinct. The anterior adenohypophysis develops from the upward migration of the Rathke pouch, an ectodermal-lined diverticulum from the embryonic mouth. The adenohypophysis is responsible for the synthesis of growth hormone, adrenocorticotrophic hormone (ACTH), and prolactin. Release of these hormones is mediated by the hypothalamus. The adenohypophysis is isointense relative to gray matter on Ti-weighted images. The neurohypophysis, infundibulum, and supraoptic and paraventricular nuclei of the hypothalamus derive from the downgrowth of neuroectoderm of the diencephalon. Antidiuretic hormone and oxytocin are synthesized in the hypothalamus and stored in the neurohypophysis until their release is dictated by the hypothalamus. It is probably the neurosecretory material that produces the high signal intensity evident on most Ti-weighted images with normal findings. Absence of this high signal is often but not always associated with compression lesions of the pituitary gland (2). Contents of the supra.sellar cistern include the infundibulum, which extends from the cephalic surface of the pituitary gland to the tuber cinereum-its junction with the hypothalamus. The optic chiasm lies anterior to the infundibulum. The mamillary bodies are located posterior to the tuber cinereum, and the midline third ventricle is cephalad to both. The infundibulum, tuber cinereum, and mamillary bodies are isointense relative to gray matter on Ti-weighted images. September 1991 Johnsen et al U RadioGraphics U 729

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a. Figure 4. (a) Drawing illustrates normal anatomy in the coronal plane through the anterior portion of the sella turcica and juxtasellar region. A = adenohypophy. sis, B = optic chiasm, C = supraclinoid internal carotid artery, D = oculomotor nerve, E = cavernous internal carotid artery, F = ophthalmic nerve, G = cavernous sinus, H = sphenoid sinus. (b) Corresponding coronal Ti-weighted MR image shows the normal anatomic structures: adenohypophysis (thick white arrow), optic chiasm (curved arrow), supraclinoid internal carotid artery (thin white arrow), cavernous internal carotid artery (arrowhead), and cavernous sinus (black arrow). (c) Corresponding enhanced coronal Ti-weighted MR image shows the normal anatomic structures: adenohypophysis (thick white arrow), optic chiasm (curved arrow), supraclinoid internal carotid artery (thin white arrow), cavernous internal carotid artery (arrowhead), oculomotor nerve (thick black arrow), ophthalmic nerve (thin black arrow), and maxillary nerve (open arrow). b. c. of the suprasellar cistern are well depicted in the coronal plane. The midline infundibulum and third ventricle are clearly identified, and the relationship between the optic chiasm and the adenohypophysis is readily evaluated. The pituitary gland is usually 5-7 mm in vertical dimension. After the administration of gadopentetate dimeglumine, the hypophysis and infundibu- lum enhance homogenously (Figs 3c, 4c) (4). The cavernous sinus enhances to the same degree as the pituitary gland, rendering the transmitted cranial nerves and cavernous carotid artery more conspicuous than on the unenhanced images. Demarcation between the pituitary gland and the cavernous sinus is more apparent on the unenhanced images. September 1991 Johnsen et al U RadioGraphics U 731

a. b. Figure 5. Microadenoma. (a) Coronal Ti-weighted MR image shows a 4-mm-diameter hypointense lesion (arrow) located within the pituitary gland, to the right of the midline. (b) On enhanced coronal Ti-weighted MR image, the hypointense lesion (arrow) becomes more apparent against the enhanced gland immediately after administration of contrast material. Table 2 Clinical and Imaging Data Summary for 20 Patients with Microadenomas Hormone Imbalance, Presentation * Numbers in parentheses represent number of female patients. t Compared with that of the normal pituitary gland on Ti-weighted images. I All lesions greater than 5 mm caused upward convexity. Mixed low to isointense signal. No. of Patients* Average Age (y) Si Intensityt Average Size Low Same High (mm)1 No. with Infundibulum Deviation Increased prolactin, amenorrhea, and galactorrhea ii (ii) 35 9 2 0 5 6 Increased ACTH, Cushing disease 6 (4) 29 2 4 0 6 3 Increased growth hormone, acromegaly 2 (1) 36 1 1 0 7 2 Nonfunctioning pitu. itary gland, parotid mass 1(1) 73 I 9 i U ADENOMA Pituitary adenomas constitute about 10% of all intracranial neoplasms and represented 54% of the lesions in our series. Adenomas are often classified by size; microadenomas are 10 mm or less in diameter, and macroadenomas are greater than 10 mm in diameter. Microadenomas are usually too small to create significant mass effect symptoms, but they come to clinical attention because of signs and symptoms of hormonal excess. Prolactinomas are the most common microadenomas and usually are accompanied by amenorrhea and galactorrhea in women. Growth hormone-secreting adenomas cause acromegaly, and ACTH-secreting tumors produce Cushing disease. Microadenomas are commonly hypointense relative to the normal pituitary gland on Tiweighted images (Table 2, Fig 5) but occasionally are isointense on unenhanced images. The appearance of microadenomas on T2-weighted images is variable (5). Because they are generally hypovascular relative to the richly vascular pituitary gland and cavernous sinus on which they may border, microade- 732 U RadioGraphics U Johnsen et a! Volume 1 1 Number 5

a. b. Figure 6. Macroadenoma. (a) Coronal Tiweighted MR image demonstrates a mass 23 mm in vertical dimension and isointense relative to white matter arising from the sella turcica. The mass displaces the optic chiasm superiorly (solid arrows), invades the right cavernous sinus, and surrounds the right internal carotid artery (open arrow). (b) On enhanced coronal Ti-weighted MR image, the mass is relatively homogeneously enhanced, with better delineation of the displaced optic chiasm (solid arrows) and the tumor margin surrounding the internal carotid artery (open arrow). (C) Photomicrograph (original magnification, x 400; H-E stain) shows nests of uniform epithelial cells that are divided by a network of delicate capillaries within fibrous strands (so-called organoid pattern). C. nomas are almost always more conspicuous immediately following enhancement (Fig 5b) (6-8). At some point after the administration of contrast material, the adenoma wash-in will equal the pituitary gland wash-out, making the lesion inconspicuous. Lesions that are isointense on initial images may be clearly visualized only after contrast material administration (9). None of the 12 cases of microadenoma in our series in which contrast material was administered showed significant enhancement. Secondary signs of microadenomas include lateral deviation ofthe infundibulum (12 of 20 [60%] in our series, occurring with all lesions that were 5 mm or greater in diameter) and focal upward convexity of the pituitary gland (55% in our series). There are caveats in the application of these secondary signs. Patients with normal pituitary glands may ex- hibit a pronounced infundibular tilt due to eccentric gland position or ectopic infundibular insertion into the gland (10). The size and shape of the pituitary gland normally vary with age and physiologic function, such that upward convexity of the gland is common in adolescent girls (1 1). Patients with macroadenomas typically present due to mass effect symptoms rather than hormonal excess. The adenoma may extend superiorly and stretch or compress the optic chiasm, compress the infundibulum, or extend laterally into the cavernous sinus. An expanding macroadenoma may also erode the sella turcica. In 34 of the 5 1 patients with macroadenomas in our series (67%), the tumor extended into the suprasellar cistern. Macroadenomas are usually isointense relative to gray matter on Ti-weighted images (Table 3, Fig 6) (42 of 51 [82%) in our series), September 1991 Johnsen et a! U RadioGrapbics U 733

Table 3 Clinical and Imaging Data Summary for 51 Patients with Macroadenomas No. with Signal Contrast Material No. with Avg Intensityt Avg Enhancement Cavernous No. with No. of Age Size Sinus Hemorrhage Presentation Pats* (y) Low Same High (mm) None Homo Hetero Extension or Necrosis Chiasmal syndrome 25 (12) 58 3 2 i 1 2.7 3 6 5 12 4 Amenorrhea and galactorrhea io (7) 30 2 8 0 2.4 2 2 3 3 2 Panhypopituitarism 7 (0) 60 1 6 0 2.3 0 3 2 2 1 Acromegaly 5(1) 35 1 4 0 2.6 4 0 1 4 0 Cushing syndrome 1 (1) 45 0 1 0 1.6 1 0 0 i 0 Palsy of third cranial nerve 1 (0) 47 0 0 1 1.3 0 0 0 0 1 Incidental 2(i) 53 0 2 0 i.3 0 0 2 0 1 Total 51(21) 49 7 42 2 2.5 10 ii 13 22 9 Note.-Hetero = heterogeneous, Homo = homogeneous, Pats = patients. * Numbers in parentheses represent number offemale patients. Compared with that of normal gray matter on Ti-weighted images. but they may be hypointense relative to the normal pituitary gland (5). The T2-weighted appearance is variable and does not generally provide additional significant diagnostic information. Most macroadenomas enhance after the administration of gadopentetate dimeglumine. Contrast material was used for examination of 34 of 5 1 macroadenomas, and 24 lesions (71%) enhanced. Eleven ofthese (46%) enhanced uniformly, and the remainder enhanced heterogeneously. Unilateral carotid artery encasement is the most specific sign of cavernous sinus invasion by macroadenoma (Fig 6b), but the sensitivity of MR imaging for such invasion is only approximately 55% (12). In our series, MR imaging demonstrated unequivocal carotid artery encasement in 22 of 51 (43%) macroadenomas. Because the medial dural reflection of the cavernous sinus is not identified on MR images, early invasion is not distinguished from dural displacement (12). Reportedly, if bilateral carotid artery displacement is present, cavernous sinus invasion most likely is not (i2). The histologic features of microadenomas and macroadenomas are the same. These tumors retain the organoid pattern of growth normally seen in the adenohypophysis (Fig 6c). However, unlike the variety of cells in the normal pituitary gland, adenomas consist of a uniform population of proliferating epithelial cells. The cells contain round to oval nuclei with benign features. Hemorrhage or necrosis accompanying pituitary adenoma is evident as high signal intensity on Ti-weighted images (Fig 7) and, in our series, occurred in nine of 5 1 macmadenomas (18%) and one of 20 microadenomas (5%) for a total of 10 of 7i lesions (i4%). In a large surgical series, hemorrhage was present in 17% of 560 cases (13). Only one ofour 10 patients with pituitary hemorrhage had acute symptoms (palsy of the third cranial nerve). Others have confirmed that intratumoral hemorrhage may be seen without clinical evidence ofpituitary apoplexy (14). Focal areas of necrosis in pituitary adenomas, as in other locations, consist of necrotic cells and cellular debris (Fig 7c). The necrotic cells may be admixed with variable amounts of fibrin deposits and hemorrhage. 734 U RadioGrapbic.s U Johnsen Ct a! Volume 11 Number 5

a. b. Figure 7. Pituitary adenoma with hemorrhage and necrosis. (a) Parasagittal Ti-weighted MR image shows a high-signal-intensity focus (solid arrow) representing methemoglobin within the central portion of a macroadenoma (open arrows). (b) On the coronal Ti-weighted MR image, the relationship of the hemorrhage (straight arrow) to the macroadenoma (open arrow) and the optic chiasm (curved arrow) is apparent. (c) Photomicrograph (original magnification, x400; H-E stain) shows areas of central necrosis (arrows) within adenoma. c. September 1991 Johnsen et a! U RadioGraphics U 735

b I3I A2.11 J,., Figure 8. Suprasellar meningioma. (a) Parasagittal Ti-weighted MR image demonstrates a relatively hypointense crescentic suprasellar mass (black arrow) extending into the posterior fossa. Contents of the suprasellar cistern are distorted. Fat-containing hyperostosis (solid white arrow) is present along the planum sphenoidale. The hypophysis (open arrow) is identified within the sella turcica. (b) Axial T2- weighted image reveals a somewhat heterogeneous, but principally hypointense mass. There is no evidence of vasogenic edema. (c) On enhanced axial Ti-weighted image, central radiating trabeculae are more apparent. Vascular flow void (straight arrows) and displacement and distortion of the mesencephalon (curved arrows) are apparent. IL I A.,,.- I a 1 U MENINGIOMA Meningiomas account for up to 18% ofall intracranial tumors. The 14 in our series represented the second most commonly diagnosed tumor in the parasellar region (about 11%). They may arise from a suprasellar (n = 6) or parasellar (n = 8) location. Suprasellar meningiomas commonly arise from the diaphragma sellae or tuberculum sellae, and vision defects caused by compression of the optic chiasm are common clinical findings. Large meningiomas originating along the planum sphenoidale or greater wing of the sphenoid bone may extend into the suprasellar cistern or parasellar regions. These tumors may be entirely parasellar if they originate from the dural wall of the cavernous sinus. Tumors involving the floor of the frontal fossa may cause anosmia due to compression of the olfactory tracts. These are tumors of adults, more commonly occurring in women. Ten of the 14 meningiomas in our series occurred in women with an average age of 64 years. Meningiomas are generally isointense relative to cortical gray matter on Ti- and T2- weighted images (12 of i4 in our series) (Figs 8, 9) (15,16). Signal variability may occur because of the presence of calcium, which re- 736 U RadioGrapbics U Johnsen et a! Volume ii Number 5

a. b. Figure 9. Parasellar meningioma. (a) Coronal Tiweighted MR image demonstrates an ill-defined mass isointense relative to gray matter (straight arrow) arising from the right cavernous sinus. Flow void in the contralateral cavernous carotid artery (curved arrow) is not present on the right, secondary to tumor invasion of the cavernous sinus. (b) On enhanced coronal Ti-weighted image, the mass (arrow) enhances homogeneously, more clearly delineating its interface with the adjacent temporal lobe. (c) Photomicrograph (original magnification, X 160; H-E stain) shows a proliferation of oval to spindleshaped cells with ill-defined eosinophilic cytoplasm and bland, oval to round nuclei. The typical whorled pattern is subtle in this case, and there are no psammoma bodies. C- suits in lower signal intensity (as in two of our 14 cases), or atypical features such as cystic components or hemorrhage. Peritumoral edema was seen in three of our cases and is best detected on T2-weighted images. Hyperostosis may be evident as focally expanded bone, which may be hyperintense on Tiweighted images due to fatty marrow. Thickened cortical bone does not produce any signal and consequently may not be as easily appreciated. Contrast material enhancement of meningioma is usually rapid and striking owing to their highly vascular nature (Figs 8c, 9b). Enhancement is commonly uniform; in all of our cases of meningioma in which contrast material was given, the tumors showed marked, uniform enhancement. Meningiomas may demonstrate linear enhancement of the adjacent dura mater-the dural tail or flare sign (17,18). Although the pathologic significance of this feature is unclear (19,20), its presence increases lesion conspicuity and is suggestive of the diagnosis. A dural tail was observed in 57% of the meningiomas in our series and was not detected with any other lesion. September 1991 Johnsen Ct a! U RadioGrapbics U 737

Figure 10. Craniopharyngioma. (a) Parasagittal Ti-weighted MR image demonstrates a homogeneous high-signal-intensity mass (arrow) filling the sella turcica and extending into the suprasellar cistern. (b) On coronal Ti-weighted image, the mass (arrow) is seen extending to the right cavernous sinus. (c) Axial T2-weighted image shows the homogeneous low-signal-intensity mass (arrow). The histologic features of meningiomas are quite variable. Typical meningiomas consist of oval to elongated bipolar cells with eosinophilic cytoplasm that are arranged in syncytial configurations and occasional whorls (Fig 9c). The round to oval nuclei appear histologically uniform and benign. Psammoma bodies (concentrically laminated calcifications) are a distinguishing feature when present. U CRANIOPHARYNGIOMA Craniopharyngiomas are epithelial neoplasms arising from squamous epithelial rests of the Rathke pouch. These benign, slow-growing tumors constitute 3%-5% of all intracranial masses and accounted for 7.6% in our series. C. Although commonly intrasellar, seven of the io craniopharyngiomas in our series were primarily suprasellar. These tumors most frequently occur in children and young adults, although they may not become clinically apparent until the middle age years. The average age of patients in our series was 34 years; seven tumors occurred in male patients and three in female patients. Chronic headache is the most common presenting complaint in adults. Large craniopharyngiomas may cause visual disturbance, interruption of cerebrospinal fluid flow, and hypothalamic-hypophyseal axis dysfunction. One of our patients presented with a seizure disorder. Children may come to clinical attention because of growth failure. The histopathologic features of craniopharyngiomas are quite variable, and this is reflected in their imaging characteristics (21); they are the most heterogeneous of all sellar 738 U RadioGraphics U Johnsen Ct a! Volume 11 Number 5

b. Figure ii. Craniopharyngioma. (a) Parasagittal Ti-weighted MR image shows a bibbed mass filling and expanding the suprasellar cistern. The inferior component (straight arrow) is isointense relative to gray matter, and the superior component (curved arrow) is hypointense. (b) On coronal Ti-weighted image obtained with contrast material, the inferior component (straight arrow) enhances homogeneously, and there is peripheral enhancement of the superior component (curved arrow). (C) Photomicrograph (original magnification, x40; H-E stain) reveals irregular islands and bands of bland squamous cells (curved arrows) lined by a layer of tall columnar cells. There is dense fibrous stroma and focal calcification (straight arrows). C- and suprasellar lesions encountered in MR imaging (Figs 10, 1 1). These tumors often have both cystic and solid components. The cystic moiety may have a high cholesterol content or contain hemorrhage, both of which may produce high Ti signal (22). Solid components more typically produce a moderate Ti signal and high T2 signal. Halfof the craniopharyngiomas we imaged showed roughly even amounts ofhigh and low signal on Tiweighted images; of the remaining tumors, three were predominantly high in signal intensity and one was predominantly low. All lesions showed some degree of signal heterogeneity. MR imaging has an important role in the evaluation of the extent of the lesion for preoperative planning and in detection of tumor recurrence (2 1,22). CT provides superior demonstration of tumoral calcification and, hence, may permit a more specific diagnosis when this common characteristic is demonstrated. This is a circumstance in which CT assumes a particularly useful role as a diagnostic adjunct. Craniopharyngiomas have a characteristic histologic appearance. There is a complex pattern of epithelial growth consisting of cords and islands of squamous cells surrounded by a layer of tall basaloid cells (Fig 1 ic). These proliferating epithelial cells are surrounded by fibrous stroma. Foci of calcification and cystic structures with necrotic debris are commonly present. September 1991 Johnseneta! U RadioGraphics U 739

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a. b. N.. \-. Figure 13. Suprasellar aneurysm. (a) Parasagittal Ti-weighted MR image demonstrates a well-circumscribed mass (1.4 cm in greatest linear dimension) (arrow) with flow void in the anterior suprasellar cistern. (b) On axial proton density-weighted image, the mass is more heterogeneous, with central areas of high signal intensity (solid arrow) from turbulent or slow flow and peripherally diminished signal (open arrows). (c) Photomicrograph (original magnification, x 20; H-E stain) shows the mouth of the aneurysm (between the arrowheads). The aneurysmal wall (single arrows) consists of fibrous tissue and lacks smooth muscle and elastic lamina, which are present in the native vessel (double arrows). C. juxtasellar mass (23) because of its marked sensitivity to flow states and hemoglobin degradation products. MR imaging reveals flow void (no signal), caused by rapid flow through the patent lumen, and heterogeneous increased signal intensity in regions of slower turbulent flow (Figs 12, 13). Peripheral, crescentic lamellae of intermediate to increased signal intensity on Ti- and T2-weighted images correspond to areas of methemoglobin and hemosiderin in mural thrombus (24). All five aneurysms in our series showed some degree of mural thrombus. The appearance of cavernous and supraclinoid internal carotid artery aneurysms is sufficiently characteristic on conventional spin-echo images that MR angiography techniques are usually not required for diagnosis. The MR appearance of giant intracranial aneurysms has been previously described (25). Histologically, the wall of the aneurysmal sac is composed of a thin layer of fibrous connective tissue (Fig i3c). Smooth muscle and elastic fibers, which are present in the normal arterial wall, are not identified in the wall of the aneurysmal sac. September 1991 Johnsen Ct a! U RadioGrapbics U 741

a. b. Figure i4 Granulomatous disease (sarcoidosis). (a) Enhanced parasagittal Ti-weighted MR image demonstrates a homogeneously enhancing mass (arrow), extending from the sella turcica to the hypothalamus. (b) On enhanced coronal Ti-weighted image, the mass is seen elevating the optic chiasm (arrow). (c) Photomicrograph (original magnification, X 40; H-E stain) of the lesion demonstrates nonnecrotizing granulomatous inflammation consisting of rounded collections of epithelioid histiocytes surrounded by lymphoid infiltrates (arrows). Special stains for organisms yielded negative results. U GRANULOMATOUS DISEASE When tuberculosis and sarcoidosis involve the central nervous system, they may occur as suprasellar masses with thickening of the infundibulum and optic chiasm. We had four such patients, three with tuberculosis and one with sarcoidosis. Two of the three patients with cranial involvement of tuberculosis had pulmonary disease as well. One patient with tuberculosis and the patient with sarcoidosis presented with neural deficits and initially did not show other manifestations. The granulomatous lesion is usually isointense relative to gray matter on Ti-weighted C- images and isointense to hyperintense on T2- weighted images (Figs 14, 15) (26). Contrast material enhancement is usually homogeneous and better delineates the parenchymal and leptomeningeal involvement (27,28). The preferential involvement of the basilar cisterns may lead to a vasculopathy of the small arteries in the anterior and posterior perforating substances. As a result, deep white matter and basal ganglion infarcts may result. 742 U RadioGraphics U Johnsen Ct a! Volume 11 Number 5

C. d. Figure 15. Granulomatous disease (tuberculosis). (a) Enhanced parasagittal Ti-weighted MR image shows diffuse irregular enhancement along the meningeal surface of the clivus (open arrow) and ventral pons (black arrow) ; contents of the suprasellar cistern are obscured (white arrow). Attendant hydrocephalus is present. (b) Enhanced coronal Ti-weighted image shows diffuse enhancement and obscuration of the contents and boundaries of the suprasellar cistern (arrow). (c) Enhanced axial Ti-weighted image shows enlarged infundibulum (arrow) and diffuse enhancement about the suprasellar cistern. (d) Photomicrograph (original magnification, x 160; H-E stain) of tuberculoma shows ill-defined granulomas present in the meninges, consisting of aggregates of epithelioid histiocytes surrounded by lymphocytes. Note the small focus of necrosis within the granuloma (arrow). Special stains demonstrated acid-fast organisms. The histologic characteristics of sarcoidosis and tuberculosis may be quite similar. In sarcoidosis, there are small granulomas consisting of well-demarcated collections of epithelioid histiocytes with admixed, multinucleated giant cells and small numbers of lymphocytes (Fig i4c). The granulomas are set in a background of mononuclear inflammatory cells. Although the granulomas in tuberculosis are typically larger with a central area of necrosis (Fig i 5d), these latter features are not specific. Special stains and cultures for acid-fast bacilli as well as fungi are required for diagnosis. September 1991 Johnsen Ct a! U RadioGraphics U 743

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a. b. :r. t4l ;;,I i; #{149}#!#{149}.#:1l;: 1.. 4 p 4#{149}4lt -,.... 4,.,.. L #{149}! I,..4 4. 1. - I-- *,-*, #{182}. #{149}1. -. Figure 17. Metastases from squamous cell carcinoma ofthe sphenoid sinus. (a) Parasagittal Tiweighted MR image shows a mass isointense relative to gray matter filling and deforming the sphenoid sinus. The clivus (open arrow) and sellar floor (solid arrow) are thinned. (b) On enhanced coronal Ti-weighted image, the homogeneously enhancing mass fills the left cavernous sinus (white arrow) as it extends through and enlarges the left foramen ovale (black arrow). (c) Photomicrograph (original magnification, x 400; H-E stain) of squamous cell carcinoma reveals sheets and nests of polygonal epithelial cells containing hyperchromatic, pleomorphic nuclei. In some areas, kertinization was noted, but, in many areas, squamous differentiation was difficult to discern. C. 5. (29). The cavernous sinus and sella turcica can both be invaded by direct extension of nasopharyngeal tumors, usually squamous cell carcinoma (Fig 17). In general, the histologic features of metastatic carcinoma are similar to those seen in the primary tumor (Fig i6c). Metastatic squamous cell carcinoma, which is moderately well differentiated, will contain sheets and nests of polygonal cells with dark, irregular nuclei (Fig i7c). Keratinization of the cytoplasm is usually apparent. U CHIASMATIC GLIOMA Chiasmatic gliomas are often low grade when they occur in children, and they have a strong association with neurofibromatosis type 1. All three cases in our series were in children with neurofibromatosis type 1. The lesion is typically more malignant and locally aggressive in adults. The tumor may arise from one or both optic nerves or the optic chiasm and typically extends along the optic apparatus. Optic gliomas are hypointense to isointense relative to gray matter on short TRITE images September 1991 Johnsen Ct a! U RadioGraphics U 745

:.; :? p Figure 18. Chiasmatic glioma. (a) Parasagittal Tiweighted MR image demonstrates the optic chiasm and proximal optic tracks, which are enlarged and infiltrated by a mass that is isointense relative to gray matter (arrow). (b) On axial Ti-weighted image, the optic chiasm (arrow) is enlarged and deformed. (c) Photomicrograph (original magnification, x 160; H-E stain) shows astrocytic proliferation with nuclear hyperchromasia and mild to moderate pleomorphism (grade 2) (arrows). (Fig 18), but their full extent is generally appreciated. They are mildly to strongly hyperintense on long TRITE images (30,3i). Contrast material enhancement occurs to varying degrees in virtually all lesions, generally in a homogeneous fashion. The histologic features of gliomas are similar in various regions of the brain. Chiasmatic and hypothalamic gliomas are usually lowgrade gliomas consisting of mildly increased numbers of round to oval glial cells within a fibrillary background (Fig i8c). The nuclei are slightly more hyperchromatic and irregularly shaped, compared with benign glial cells. These gliomas may contain cystic areas and histologically resemble pilocytic astrocytomas seen in the cerebellum. Increasing cellularity, cellular pleomorphism, vascular proliferation, increased numbers of mitoses, and foci of necrosis are features of higher grade gliomas. C. U ARACHNOID CYST Arachnoid cysts are collections of fluid similar to cerebrospinal fluid contained within the arachnoid membrane. They most commonly occur on the middle cranial fossa and may extend secondarily into the suprasellar cistern. Alternatively, the cysts may occur primarily within the suprasellar cistern. In one of our three patients, the cyst was entirely intrasellar. The cysts may be congenital or acquired and may attain sufficient size to cause symptoms related to the optic apparatus or hypothalamic-hypophyseal axis (32). Two of our three patients were young adults with persistent headaches, one ofwhom also had decreased libido. The third patient was an infant with myoclonus. 746 U RadioGraphics U Johnsen Ct a! Volume 1 1 Number 5

C. d. Figure 19. Arachnoid cyst. (a) Parasagittal Ti-weighted MR image shows an ill-defined suprasellar mass causing upward displacement of the hypothalamus and optic apparatus (thin arrow) and dorsal displacement of the pons (thick arrow). The mass is isointense relative to cerebrospinal fluid. (b) On coronal Tiweighted image, the mass extends into the left middle cranial fossa (straight arrow). The suprasellar component of the mass (curved arrow) has signal intensity slightly greater than that of cerebrospinal fluid, perhaps secondary to trapped protein or cerebrospinal fluid flow. (c) On axial T2-weighted image, the mass (arrow) is essentially isointense relative to cerebrospinal fluid. (d) Photomicrograph (original magnification, X 40; H-E stain) of arachnoid cyst demonstrates folds of the cyst wall, which consist of delicate fibrous tissue. Flattened arachnoid cells are seen along one edge (arrow). MR images depict a smoothly marginated mass that is isointense relative to cerebrospinal fluid with all spin-echo sequences (Fig 19) (33). The extra-axial origin, degree of mass effect, and cyst extension are accurately depicted. Vasogenic edema is not a feature of this lesion. Histologically, arachnoid cysts lie within the arachnoid membrane (Fig i9d). The thin cyst wall is composed of collagen and a lining of flattened arachnoid cells. September 1991 Johnsen et a! U RadioGraphics U 747

a. D. Figure 20. Hypothalamic glioma. (a) Parasagittal Ti-weighted MR image shows a hypointense mass, 4 cm in greatest linear dimension, filling the sella turcica, filling the suprasellar cistern, and roughly conforming to the contour of the third ventricle. Normal contents of the suprasellar cistern are obscured. (b) On enhanced axial Ti-weighted image obtained after biopsy, the enhanced tumor is relatively homogeneous except for two small cystic components (arrows). Postoperative extraaxial fluid collections are present in the frontal fossae bilaterally. U HYPOTHALAMIC GLIOMA Hypothalamic gliomas are tumors of childhood and adolescence and usually are accompanied by vision disturbance, hydrocephalus, diencephalic syndrome, or diabetes insipidus. Of our three patients with this lesion, one was an infant with diencephalic syndrome, one was a child with slurred speech and cranial nerve palsies, and one was an adult with a recent onset of seizures. The tumor may extend into the suprasellar cistern or the surrounding parenchyma. Similar to optic nerve gliomas, these lesions are isointense relative to brain on Ti-weighted images (Fig 20) and isointense to hyperintense relative to brain parenchyma on T2- weighted images. The lesion usually enhances homogeneously after the administration of contrast material. The origin of the lesion is usually apparent if the lesion is not too large. U HYPOTHALAMIC GERMINOMA Intracranial germinomas occur most frequently in the pineal region, with the suprasellar cistern being the second most common location. Pineal germinomas are found most often in male patients, but germinomas in the suprasellar cistern occur in both sexes with equal frequency. Patients with hypothalamic germinomas present in the 2nd to 3rd decade, often with visual or pituitary axis dysfunction. Both of our patients, one male and one female, were adolescents; one had vision disturbance, and the other had diabetes insipidus and panhypopituitarism. MR imaging demonstrates an infiltrative mass, which is usually isointense relative to brain parenchyma on Ti-weighted images 748 U RadioGraphics U Johnsen Ct a! Volume 1 1 Number 5

a. b. Figure 21 Germinoma. (a) Parasagittal Tiweighted MR image demonstrates a homogeneous mass (arrows) filling the sella turcica and extending through the suprasellar cistern to the floor of the third ventricle. (b) Coronal Ti-weighted image shows the mass extending laterally into the left cayemous sinus (arrows) and into the suprasellar cxtension. (C) Photomicrograph (original magnification, X 400; H-E stain) demonstrates tumor cells arranged in loose aggregates. The cells contain large, irregular nuclei with prominent nucleoli (thick arrow). There are small, dark lymphocytes (thin arrow) in the surrounding fibrous stroma. C- (Fig 21). The mass is generally hyperintense relative to brain parenchyma on T2-weighted images and enhances homogeneously after contrast material administration. Histologically, hypothalamic germinomas are similar to the testicular germ cell tumor, seminoma, and the ovarian germ cell tumor, dysgerminoma. There are loosely cohesive aggregates of large cells (germ cells) containing large nuclei with prominent nucleoli (Fig 2 ic). Associated with these large tumor cells are scattered, small lymphocytes with benign cytologic features located in the fibrous septa. U SCHWANNOMA Schwannomas account for 8% of all primary intracranial neoplasms and most frequently involve the vestibular branch of the acoustic nerve in the cerebellopontine angle. The trigeminal nerve is much less commonly involved, but it is the most frequently affected nerve in the parasellar region. Schwannomas of the third, fourth, and sixth cranial nerves are rare. The two patients in our series were adults with rapidly progressive worsening of vision. Schwannomas are usually hypointense rd. ative to gray matter on Ti-weighted images but may occasionally be isointense (Fig 22). They are almost always hyperintense on T2- weighted images (34). Homogeneous enhancement occurs following administration of gadopentetate dimeglumine. September 1991 Johnsen Ct a! U RadioGraphics U 749

,. I r b L... : fj 4....-#{149}, Figure 22. Schwannoma. (a) Parasagittal Tiweighted MR image demonstrates a 10-mm retrosellar mass (arrow) isointense relative to gray matter indenting the upper pons. (b) Coronal Ti-weighted image shows the left parasellar mass (arrow) displacing the uncus laterally. (c) Photomicrograph (original magnification, x 40; H-E stain) reveals interlacing bundles of spindle cells (arrows) whose nuclei tend to form columns. U.. 4. : 5. 4. 1. #{149} #{149} -.....: 6 The histologic characteristics of schwannomas are somewhat variable, but in the typical schwannoma there is an admixture of two histologic patterns, both containing spindle Schwann cells (Fig 22c). In the first pattern (Antoni type A tissue), there are increased numbers of elongated, bipolar Schwann cells with a small amount of cytoplasm. The nuclei are in swirling or streaming patterns, characteristically forming palisading arrangements (Verocay bodies). In the second pattern (Antoni type B tissue), there is decreased cellularity and the Schwann cells have occasional vacuolated cytoplasm. Typically, there are thickwalled blood vessels within the tumor. U EPIDERMOID Epidermoids are developmental epithelial inclusion cysts; they occur most commonly along the petrous apex and cerebellopontine angle or in the juxtasellar region. The lesion accounts for less than 2% of all intracranial tumors and generally develops in patients 30-60 years of age, occurring slightly more often in men. Symptoms vary by location and are related to the slowly increasing size of the mass. Both of our patients were adults with chronic headaches. These lesions, despite their high cholesterol content, are generally isointense relative to cerebrospinal fluid on Ti-weighted images (Fig 23). Prolongation ofthe Ti relaxation time may be secondary to the heterogeneity of the contents or the chemical state of the 750 U RadioGraphics U Johnsen Ct a! Volume 1 1 Number 5

b. Figure 23. Epidermoid. (a) Parasagittal Tiweighted MR image shows an irregular mass (arrows), isointense relative to cerebrospinal fluid, filling the suprasellar cistern and extending along the clivus displacing the brain stem dorsally. (b) On axial Ti-weighted image, the mass fills the suprasellar and right ambient cisterns, displacing and deforming the mesencephalon (open arrow), optic chiasm (curved arrow), and infundibulum (straight arrow). (c) Photomicrograph (original magnification, x 160; H-E stain) of epidermoid shows that the cyst wall consists of attenuated, stratified squamous epithehum (solid arrow), giving rise to laminated keratinous material that fills the cyst (open arrow). C. cholesterol. The cholesterol of these lesions, unlike that of craniopharyngiomas, is not hydrolyzed. The T2-weighted appearance of epidermoids is variable, ranging from hypointense to hyperintense with respect to gray matter, but they tend toward relative T2 prolongation (35,36). Peritumoral parenchymal edema is not a feature of epidermoids. The histologic appearance is characterized by orderly stratified squamous epithelium that lines a central cystic region (Fig 23c). Desquamation of the epithelial lining contributes to the cellular debris, keratin, and cholesterol crystals within the cyst. U RATHKE CLEFT CYST These epithelial cysts arise from the Rathke cleft, which is a remnant of the Rathke pouch, an ectodermal extension of the embryonic oral cavity. The Rathke pouch is the precursor of the anterior lobe, pars intermedia, and pars tuberalis of the hypophysis. The Rathke cleft cysts develop in the midline within the sella turcica. The lesions are usually tiny and asymptomatic; rarely, they attain sufficient size to produce vision disturbances, headache, diabetes insipidus, or hypopituitarism. Our two patients were both young girls, one with chronic headaches and the other with a presumably unrelated seizure disorder. September 1991 Johnsen Ct a! U RadioGrapbics U 751

a. b. Figure 24. Rathke cleft cyst. (a) Parasagittal Tiweighted MR image shows a 3.0-cm mass (thick arrow), homogeneous and isointense relative to gray matter, extending from an enlarged sella turcica through the suprasellar cistern to the base of the third ventricle. The optic chiasm (thin arrow) is commensurately displaced. (b) Coronal Tiweighted image better demonstrates superior displacement of the optic chiasm (arrow). (C) Photomicrograph (original magnification, x400; mucicarmine stain) shows stratified squamous epithelium with orderly maturation and mucin-containing cells (arrow) staining red. A few ciliated cells were also identified (not shown). The appearance of a Rathke cleft cyst on MR images reflects its composition (Fig 24) (37,38). Simple serous cysts may be isointense relative to cerebrospinal fluid with all spin-echo sequences. Mucoid contents, cholesterol, and desquamated debris contribute to signal variability. The epithelial wall may enhance after contrast material administration. The cyst wall is lined by stratified squamous epithelium (Fig 24c). Scattered ciliated cells and mucin-containing cells are typical features that allow differentiation of a Rathke cleft cyst from an epidermoid cyst. The cyst contains serous or mucoid fluid with variable amounts of desquamated debris. U CHORDOMA Chordomas are slow-growing neoplasms that develop from notochord remnants. The clivus is the second most frequent site of origin, accounting for 35% of these tumors. Although usually midline, the tumors may originate from a parasellar location. They are twice as common in male patients and typically occur in adulthood. Both our patients were men with vision disturbances. Seventy-five percent of chordomas are isointense relative to gray matter on Tiweighted images; the remainder are hypointense and nearly always show increased signal intensity on T2-weighted images (39). In both 752 U RadioGraphics U Johnsen Ct a! Volume 11 Number 5

C. d. Figure 25. Chordoma. (a) Enhanced parasagittal Ti-weighted MR image shows a bibbed enhanced mass (arrow) extending posteriorly from the parasellar region, displacing the pons. (b) On coronal Ti-weighted image, the mass (arrow) is slightly heterogeneous but predominantly isointense relative to gray matter. (c) Enhanced coronal Ti-weighted image more clearly shows the extraaxial nature ofthe lesion, its relationship to the carotid artery (arrow), and laminated matrix. (d) Photomicrograph (original magnification, X 160; H-E stain) demonstrates ill-defined cords of tumor cells with mildly pleomorphic but otherwise bland nuclei. Some cells contain vacuolated cytoplasm (physaliphorous cells), and there are areas ofmyxoid stroma. our patients, the chordomas had low signal intensity on Ti-weighted images (Fig 25) and heterogeneous high signal intensity on T2- weighted images. In the patient who received contrast material, the tumor enhanced intensely. MR imaging also allows qualitative and quantitative differentiation between the typical physaliphorous chordoma and the chondroid type. The latter is typically less in- September 1991 Johnsen Ct a! U RadioGraphics U 753

;;;;;tc;; ;;;;o;;;;;;i;; cit;f;1;i;- strating calcifications, bone sequestra, and destruction of bone typical of chordoma (40). As in the assessment of craniopharyngiomas, CT is complementary to MR imaging in evaluation of chordomas. Chordomas typically contain cords of large multivacuolated cells (physaliphorous cells) within a myxoid stroma (Fig 25d). The chondroid type has cartilaginous foci within the tumor. U CHONDROSARCOMA Chondrosarcoma is a malignant bone tumor whose cells produce hyaline cartilage. Although it is rare in the spine (5%-9% frequency) it may originate from the clivus and involve the sella turcica. It occurs in adults. Our patient was a 77-year-old woman with right sixth cranial nerve palsy and a history of intermittent diplopia. Although pathologically distinct from chordoma, clival chondrosarcoma has similar to identical MR imaging features (Fig 26) (40). Both lesions had prolonged Ti and T2 relaxation times and enhanced after contrast material administration. MR imaging delineates tumor extent better than CT, but the latter is useful for demonstrating intratumoral calcifications and bone destruction, and it is the method of choice for routine follow-up of therapy (40). Low-grade chondrosarcoma is histologically similar to normal cartilage. Benign-appearing chondrocytes are present within abundant chondroid matrix (Fig 26c). The presence of focal areas of mildly increased cellularity and mild cytologic atypia are subtle features of malignant disease that must be correlated with clinical and radiologic findings. Although the chondroid subtype of chordoma may be 754 U RadioGraphics U Johnsen Ct a! Volume 1 1 Number 5

a. intermittent obstruction of one or both forab. Figure 27. Colloid cyst. (a) Parasagittal Tiweighted MR image shows a well-circumscribed, 3-cm, high-signal-intensity mass (arrow) in the suprasellar region. The mass fills much of the third ventricle. (b) On coronal Ti-weighted image, the midline mass (arrow) arises from the superior third ventricle and extends into the body of each lateral ventricle through the foramina of Monro with resultant obstructive hydrocephalus. (c) Photomicrograph (original magnification, x 40; H-E stain) shows the cyst wall, lined by cuboidal epithelium. The cyst contains homogeneous pink proteinaceous material. C. difficult to differentiate from chondrosarcoma, the latter does not have the elongated cords and strands of cells characteristic of chordoma. U COLLOID CYST Colloid cysts are rare, benign cysts originating from infolding of primitive neuroepithelium of the tela choroidea (4 1). Symptomatic cysts are characteristically located in the anterosuperior aspect of the third ventricle, adjacent to the foramina of Monro, but they may extend into the suprasellar cistern if they grow sufficiently large. The cyst enlarges by means of accumulating secretory products and cells; cholesterol content is variable. Commonly, patients present due to symptoms of acute hydrocephalus produced by mina of Monro. Our patient had chronic, severe intermittent headache. The MR imaging appearance of colloid cysts is typically heterogeneous, reflecting the variability ofcyst composition (Fig 27). Many cysts are hypointense to isointense relative to gray matter on Ti-weighted images, but increased cholesterol content shortens the Ti relaxation time, producing increased signal intensity (42) as in our case. The T2-weighted images most often reveal high signal intensity that may contain a central focus of low signal; however, this appearance is not specific for colloid cysts (43). On histologic examination, the colloid cyst lining is typically composed of benign cuboidal epithelium (Fig 27c). The cyst contains homogeneous, amorphous proteinaceous September 1991 Johnsen Ct a! U RadioGraphics U 755

756 U Radio

U SUMMARY We assessed the MR imaging characteristics of i3 1 pathologically or clinically proved sellar and juxtasellar lesions. Adenoma, meningioma, craniopharyngioma, and aneurysm constituted 76% of the lesions in our series. The MR imaging characteristics of the four most common lesions were sufficiently distinct to allow them to be differentiated from each other and from most other entities. Other characteristics such as extrasellar versus intrasellar location, nature of contrast material enhancement, the presence of cystic components, and clinical findings permit further differentiation among the various other abnormalities. The superior resolution and multiplanar capacity of MR imaging best depicts the extent of sellar and juxtasellar lesions. Acknowledgments: The authors wish to acknowledge the special efforts of those who assisted in the manuscript preparations: the Geisinger Medical Center MR imaging technical staff; Joseph Mentrikoski and the staff of the medical photography department; the medical transcriptionist staff; and Javad Towfighi, MD, Department of Pathology, Hershey Medical Center, Pennsylvania State University School of Medicine. The illustrations were prepared by Lisa Pe#{241}alver. U REFERENCES 1. Daniels DL, Pojunas KW, Kilgore DP, et al. MR of the diaphragma sellae. AJNR 1986; 7:765-769. 2. Colombo N, Berry I, KucharczykJ, et al. Posterior pituitary gland: appearance on MR images in normal and pathologic states. Radiology 1987; 165:481-485. 3. Daniels DL, Pech P, Mark L, Pojunas K, Williams AL, Haughton VM. Magnetic resonance imaging of the cavernous sinus. AJNR 1985; 6: 187-192. 4. Davis PC, HoffmanJC, MalkojA, et al. Gadolinium-DTPA and MR imaging of pituitary adenoma: a preliminary report. AJNR 1987; 8: 817-823. 5. Kucharczyk W, Davis DO, Kelly WM, Sze G, Norman D, Newton TH. Pituitary adenomas: high-resolution MR imaging at 1.5 T. Radiology 1986; 161:761-765. 6. Dwyer AJ, FrankJA, DoppmanJL, et al. Pituitaly adenomas in patients with Cushing disease: initial experience with Gd-DTPA-enhanced MR imaging. Radiology 1987; 163: 421-426. 7. DoppmanJL, FrankJA, DwyerAJ, et al. Gadolinium DTPA-enhanced MR imaging of ACTH-secreting microadenomas of the pituitaly gland. J Comput Assist Tomogr 1988; 12:728-735. 8. Mild Y, Matsuo M, Nishizawa 5, et a!. Pituitary adenomas and normal pituitary tissue: enhancement patterns on gadopentetate-enhanced MR imaging. Radiology i990; 177:35-38. 9. Steiner E, Imhof H, Knosp E. Gd-DTPA enhanced high resolution MR imaging of pituitaly adenomas. RadioGraphics 1989; 9:587-598. 10. Ahmadi H, Larsson EM, Jinkins JR. Normal pituitary gland: coronal MR imaging of infundibular tilt. Radiology 1990; 177:389-392. 1 1. Elster AD, Chen MYM, Williams DW, Key LL. Pituitary gland: MR imaging of physiologic hypertrophy in adolescence. Radiology 1990; 174:681-685. 12. Scotti G, Yu CY, Dillon WP, et al. MR imaging of cavernous sinus involvement by pituitaiy adenomas. AJNR 1988; 9:657-664. 13. Wakai 5, Fukushima T, Teramoto A, Sano K. Pituitary apoplexy: its incidence and clinical significance. J Neurosurg 1981; 55:187-193. 14. Ostrov SG, Quencer RM, HoffmanJC, Davis PC, Hasso AN, David NJ. Hemorrhage within pituitary adenomas: how often associated with pituitary apoplexy syndrome? AJNR i989; 10:503-5 10. 15. YeakleyJW, Kulkarni MV, McArdle CB, Haar FL, Tang RA. High resolution MR imaging of juxtasellar meningiomas with CT and angiographic correlation. AJNR 1988; 9:279-285. 16. Spagnoli MV, Goldberg HI, Grossman RI, et al. Intracranial meningiomas: high-field MR imaging. Radiology 1986; 161:369-375. 17. Aoki 5, Sasaki Y, Machida T, Tanioka H. Contrast-enhanced MR images in patients with meningioma: importance of enhancement of the dura adjacent to the tumor. AJNR 1990; 11:935-938. 18. Sch#{228}rnerW, Schubeus P, Henkes H, Lanksch w, Felix R. Meningeal sign : a characteristic finding of meningioma on contrast-enhanced MR images. Neuroradiology 1990; 32:90-93. 19. Goldsher D, Litt AW, Pinto RS, Bannon KR, Kricheffll. Dural tail associated with meningiomas on Gd-DTPA-enhanced MR images: characteristics, differential diagnostic value, and possible implications for treatment. Radiology 1990; 176:447-450. 20. Tokumaru A, O uchi T, Eguchi T, et al. Prominent meningeal enhancement adjacent to meningioma on Gd-DTPA-enhanced MR images: histopathologic correlation. Radiology 1990; 175:431-433. 21. Pusey E, Kortman KE, Flannigan BD, Tsuruda J, Bradley WG. MR of craniopharyngiomas: tumor delineation and characterization. AJNR 1987; 8:439-444. 22. Freeman MP, Kessler RM, AllenJH, Price AC. Craniopharyngioma: CT and MR imaging in nine cases. J Comput Assist Tomogr 1987; 11:810-814. 23. Kamaze MG, Sartor K, WinthropJD, Gado MH, Hodges FJ. Suprasellar lesions: evalua- September 1991 Johnsen Ct a! U RadioGraphics U 757