KEY FACTS Terminology Arachnoid cyst (AC): Developmental arachnoid duplication anomaly creating cerebrospinal fluid (CSF)-filled sac Imaging Sharply demarcated ovoid extraaxial cisternal cyst with imperceptible walls with CSF density (CT) or intensity (MR) AC signal parallels (is isointense to) CSF on…
KEY FACTS Terminology Definition: Congenital inclusion of ectodermal epithelial elements during neural tube closure Imaging CPA cisternal insinuating mass with high signal on DWI MR 90% intradural, 10% extradural; margins usually scalloped or irregular; cauliflower-like margins with “fronds” possible TI…
Terminology The contents of the cerebellopontine angle (CPA) and internal auditory canal (IAC) cisterns include the facial nerve (CN7), the vestibulocochlear nerve (CN8), and the anterior inferior cerebellar artery (AICA) loop. The bony IAC, its fundal crests (vertical and horizontal),…
KEY FACTS Terminology Lymphocytic hypophysitis (LH) Synonyms: Adenohypophysitis, primary hypophysitis, stalkitis Idiopathic inflammation of pituitary gland &/or stalk Imaging Thick stalk (> 2 mm + loss of normal “top to bottom” tapering) ± enlarged pituitary gland 75% show loss of…
KEY FACTS Terminology Upper limit of normal pituitary height varies with age, sex Pregnant/lactating female patients: 12 mm Young menstruating female patients: 10 mm Male patients, postmenopausal women: 8 mm Infants, children: 6 mm Nonphysiologic hyperplasia seen with Hypothyroidism, Addison…
KEY FACTS Terminology Benign, often partially cystic sellar region tumor derived from Rathke pouch epithelium 2 types Adamantinomatous (cystic mass in childhood) Papillary (solid mass in older adults) Imaging General features Multilobulated, often large (> 5 cm) Occasionally giant, multicompartmental…
KEY FACTS Terminology Nonneoplastic cyst arising from remnants of embryonic Rathke cleft Benign sellar region endodermal cyst lined by ciliated, mucus-producing epithelium Imaging Nonenhancing, noncalcified, intrasellar &/or suprasellar cyst with intracystic nodule Completely intrasellar (40%), suprasellar extension (60%) Density/signal intensity…
KEY FACTS Terminology Acute clinical syndrome with headache, visual defects/ophthalmoplegia, altered mental status, variable endocrine deficiencies Caused by either hemorrhage or infarction of pituitary gland Preexisting pituitary macroadenoma common Imaging CT Sellar/suprasellar mass with patchy or confluent hyperdensity Peripheral enhancement,…
KEY FACTS Terminology Benign neoplasm of adenohypophysis Imaging Upward extension of macroadenoma = most common suprasellar mass in adults Best imaging technique MR with sagittal/coronal thin-section imaging through sella + T1 C+ with FS Sellar mass without separate identifiable pituitary…
KEY FACTS Terminology Microadenoma: ≤ 10 mm in diameter Imaging Intrasellar mass is typical location Rare: Ectopic origin outside pituitary fossa Best technique = dynamic contrast-enhanced thin-section T1-weighted MR Generally enhance more slowly than adjacent normal pituitary Beware: 10-30% can…