Neuroradiology 4 Flashcards
Tornwaldt cysts
Benign midline nasopharynx lesion of high T2 signal. Believed to be remnant of notochordal tissue (benign).
Triad of nasopharyngeal malignancy
1) Mucosal mass of lateral nasopharynx (fossa of Rosenmuller). (2) Lateral retropharyngeal nodes. (3) Mastoid opacification (eustachian tube dysfunction)
Head and neck paragangliomas
Vascular tumors arising from neural crest cell derivatives. Names given according to location: Carotid body tumor (at carotid bifurcation). Glomus vagale tumor (vagus nerve). Glomus jugulare tumor (jugular ganglion of vagus nerve). Glomus tympanicum tumor (Arnold and Jacobson nerves of middle ear).
This lymph node chain serves as the final common afferent pathway for lymphatic drainage of the entire head and neck.
Internal jugular nodal chain
Pathologic size of head and neck lymph nodes
Jugulodigastric and submandibular nodes may normally measure up to 1.5 cm. All other nodes up to 1.0 cm.
Common optic nerve sheath complex tumors
Optic nerve glioma. Optic sheath meningioma.
Optic nerve glioma
Low grade pilocytic astrocytoma. Most common tumor of optic nerve. Typically occurs during first decade of life. High association with neurofibromatosis type 1. Enlarged sheath complex may be tubular, fusiform, or eccentric with kinking. Rarely calcify.
Most common cause of intraorbital mass in an adult
Idiopathic inflammatory pseudotumor. Inflammatory lymphocytic infiltrate. Involves tendinous attachments to the globe. Often rapidly develops presenting with painful proptosis, chemosis, and ophthalmoplegia.Lymphoma tends to present with painless proptosis.
Enlargement of extraocular muscles with sparing of tendinous attachments to the globe
Thyroid ophthalmopathy (Graves disease). Causes unilateral or bilateral proptosis in adults. Muscles involved, in decreasing order: I’M SLow. Inferior rectus. Medial rectus. Superior rectus. Lateral retus.
Lesions of the lacrimal gland
Inflammatory: Sarcoidosis. Sjogren syndrome. Neoplastic: Salivary gland (mixed-cell tumor or adenoid cystic carcinoma). Lymphoma. Pseudotumor. Dermoid (fat-fluid level).
Retinoblastoma features
Most common primary ocular malignancy. Leukocoria. Calcified ocular mass.
Thyroglossal duct
Epithelium-lined tract along which primordial thyroid gland migrates. Extends from foramen cecum (tongue base) to anterior of thyrohyoid membrane and strap muscles to ends at thyroid isthmus. Normally involutes by 8 to 10 weeks of gestation. May give rise to cyst, sinus tract, or ectopic thyroid tissue.
The usual clinical presentation is that of a painless neck mass along the anterior border of the sternocleidomastoid muscle, presenting during the first to third decade.
Second branchial cleft cyst. Anterior to mid sternocleidomastoid muscle. Lateral to internal jugular vein at the level of carotid bifurcation.
Intracranial air, pneumocephalus, may be seen with what fractures
Compound skull fractures. Fractures involving paranasal sinuses.
Von Hippel-Lindau syndrome imaging manifestations
Visceral: Renal cell carcinomas. Pheochromocytomas. Pancreatic islet cell tumors. Pancreatic, hepatic, renal, and splenic cysts. CNS: Retinal capillary hemangiomas. Spinal cord and posterior fossa hemangioblastomas. Endolymphatic sac adenocarcinomas.
Distinguishing epidermoids from arachnoid cysts on MR imaging.
Both follow CSF T1 and T2 signal. Epidermoids restrict diffusion, are bright at DWI. Arachnoid cysts do not restrict diffusion. Epidermoids are composed of epithelial cells that grow in layers. Arachnoid cysts contains CSF.
Define DWI pulse sequence
Diffusion-weighted imaging (DWI) is a form of MR imaging based upon measuring the random Brownian motion of water molecules within a voxel of tissue. In general simplified terms, highly cellular tissues or those with cellular swelling exhibit lower diffusion coefficients. Diffusion is particularly useful in tumor characterization and cerebral ischemia.
Leptomeningeal cyst
Known as a growing fracture. Caused by traumatic tear of the dura. Outpouching of arachnoid at site of suture or skull fracture.
Le Fort I
Floating palate. Horizontal fracture through maxillary sinuses, nasal septum, and inferior ptyergoid plates.
Le Fort II
Pyramidal fracture through bridge of nose, medial orbits, lateral and posterior maxillary walls, nasal septum, inferior orbital rim (infraorbital nerve injury), and midportion of ptyergoid plates.
Le Fort III
Craniofacial dysjunction. Horizontal fracture through orbits. Begins near nasofrontal suture and extends posteriorly through nasal septum, medial and lateral orbit walls, zygomatic arch, and base (superior aspect) of pterygoid plates.
Diffusion-Weighted MR in Acute Ischemia
Brain water diffusion rates fall rapidly during acute ischemia. Bright signal on DWIs.
Apparent diffusion coefficient (ADC).
Reflects pure diffusion behavior. Free of underlying T2 contributions (shine through or dark through).
Fluid-Attenuated Inversion Recovery (FLAIR) in Ischemia
Suppresses free water CSF signal but allows T2 weighting of parenchyma. Increases conspicuity of T2 changes in ischemia. May help detect small cortical lesions and acute subarachnoid hemorrhage.
Maximal brain swelling post brain infarction occurs at what days
3 to 7 days postinfarction.
Encephalomalacia post brain infarction occurs when
30 to 90 days (1 to 3 months) postinfarction.
