T1 Signal Hyperintensity in the Sellar Region: Spectrum of Findings

Abstract

T1 signal hyperintensity is a common finding at magnetic resonance imaging of the sellar region. However, this signal intensity pattern has different sources, and its significance depends on the clinical context. Normal variations in sellar T1 signal hyperintensity are related to vasopressin storage in the neurohypophysis, the presence of bone marrow in normal and variant anatomic structures, hyperactive hormone secretion in the anterior pituitary lobe (eg, in newborns and pregnant or lactating women), and flow artifacts and magnetic susceptibility effects. Pathologic variations in T1 signal hyperintensity may be related to clotting of blood (in hemorrhagic pituitary adenoma, pituitary apoplexy, Sheehan syndrome, or thrombosed aneurysm) or the presence of a high concentration of protein (Rathke cleft cyst, craniopharyngioma, or mucocele), fat (lipoma, dermoid cyst, lipomatous meningioma), calcification (craniopharyngioma, chondroma, chordoma), or a paramagnetic substance (manganese, melanin). After treatment, T1 signal hyperintensity may result from the presence of materials used for surgical packing (gelatin sponge, fat); from compression of the cavernous sinus and reduction of the venous flow, caused by overpacking of the operative bed; or from hormone hypersecretion by a remnant of normal tissue in the anterior lobe of the pituitary gland.

Endoscopic Endonasal Transsphenoidal Treatment of Pituitary Apoplexy: Outcomes in a Series of 20 Patients

“…In the MR images, acute and subacute hemorrhage characteristically exhibited T1 hyperintensity on pre-contrast imaging with minimal or no enhancement on post-contrast imaging, consistent with previous descriptions of intratumoral hemorrhage [21][22]. The tumor was distinguished from normal pituitary by virtue of its morphology and hypoenhancement on post-contrast T1-weighted images.…”

Fluid-fluid level on magnetic resonance images may predict the occurrence of pituitary adenomas in cystic sellar-suprasellar masses

“…Repeated bleeding may occur on the basis of ischemic necrosis or hemorrhagic necrosis (11)(12)(13). Various previous studies have suggested that fluid-fluid level within a fluid cavity is induced by the sedimentation of blood products at the subacute or chronic stage, as well as the separation of unclotted blood as opposed to serous (interstitial) fluid (6,(10)(11)(12)14,15). These studies indicate that fluid-fluid levels are typically presented as high/low signal patterns on axial (or sagittal) T2-weighted images, or partially on T1-weighted images as high/slightly high (or isointense) features.…”

“…On MRI, RCC is typically exhibited as an intrasellar cystic lesion with suprasellar extension that is ovoid or kidney shaped and well demarcated, and exhibits no calcification, a lack of or a thin cyst wall enhancement, orintracystic nodules (2). Craniopharyngiomas are typically presented as superiorly lobulated shaped sellar-suprasellar heterogeneous lesions, with mixed solid and cystic characteristics, calcification, reticular enhancement of the solid portion, and third ventricle compression by superior tumor extension (8,15,23). In various previous studies, intracystic nodules have been regarded to have diagnostic value for RCC, which typically displays distinctive characteristics, including T1-weighted hyperintensity, T2-weighted hypointensity, and no gadolinium enhancement (24)(25)(26).…”

“…Furthermore, axial or sagittal images are necessary to exclude the identification of a fluid-fluid level. Bonneville et al (15) have previously suggested that a fluid-fluid level is beneficial in differentiating adenoma from RCCs and craniopharyngiomas. To the best of our knowledge, only a few cases of bleeding in RCCs and craniopharyngiomas have been described, and it has been suggested that bleeding is a result of compressed portal veins or newly organized thin-wall vessels within the granulation tissue of the cyst wall, particularly in large cysts (15,27).…”

Pituitary apoplexy: pathophysiology, diagnosis and management

“…After gadolinium, a peripheral enhancement is represented by a thin peripheral rim. In the chronic phase, there is signal increase in both T 1 and T 2-weighted images (39,40).…”