Neuroradiology 4

Question 1

Tornwaldt cysts

Answer 1

Benign midline nasopharynx lesion of high T2 signal. Believed to be remnant of notochordal tissue (benign).

Question 2

Triad of nasopharyngeal malignancy

Answer 2

1) Mucosal mass of lateral nasopharynx (fossa of Rosenmuller). (2) Lateral retropharyngeal nodes. (3) Mastoid opacification (eustachian tube dysfunction)

Question 3

Head and neck paragangliomas

Answer 3

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).

Question 4

This lymph node chain serves as the final common afferent pathway for lymphatic drainage of the entire head and neck.

Answer 4

Internal jugular nodal chain

Question 5

Pathologic size of head and neck lymph nodes

Answer 5

Jugulodigastric and submandibular nodes may normally measure up to 1.5 cm. All other nodes up to 1.0 cm.

Question 6

Common optic nerve sheath complex tumors

Answer 6

Optic nerve glioma. Optic sheath meningioma.

Question 7

Optic nerve glioma

Answer 7

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.

Question 8

Most common cause of intraorbital mass in an adult

Answer 8

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.

Question 9

Enlargement of extraocular muscles with sparing of tendinous attachments to the globe

Answer 9

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.

Question 10

Lesions of the lacrimal gland

Answer 10

Inflammatory: Sarcoidosis. Sjogren syndrome. Neoplastic: Salivary gland (mixed-cell tumor or adenoid cystic carcinoma). Lymphoma. Pseudotumor. Dermoid (fat-fluid level).

Question 11

Retinoblastoma features

Answer 11

Most common primary ocular malignancy. Leukocoria. Calcified ocular mass.

Question 12

Thyroglossal duct

Answer 12

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.

Question 13

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.

Answer 13

Second branchial cleft cyst. Anterior to mid sternocleidomastoid muscle. Lateral to internal jugular vein at the level of carotid bifurcation.

Question 14

Intracranial air, pneumocephalus, may be seen with what fractures

Answer 14

Compound skull fractures. Fractures involving paranasal sinuses.

Question 15

Von Hippel-Lindau syndrome imaging manifestations

Answer 15

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.

Question 16

Distinguishing epidermoids from arachnoid cysts on MR imaging.

Answer 16

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.

Question 17

Define DWI pulse sequence

Answer 17

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.

Question 18

Leptomeningeal cyst

Answer 18

Known as a growing fracture. Caused by traumatic tear of the dura. Outpouching of arachnoid at site of suture or skull fracture.

Question 19

Le Fort I

Answer 19

Floating palate. Horizontal fracture through maxillary sinuses, nasal septum, and inferior ptyergoid plates.

Question 20

Le Fort II

Answer 20

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.

Question 21

Le Fort III

Answer 21

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.

Question 22

Diffusion-Weighted MR in Acute Ischemia

Answer 22

Brain water diffusion rates fall rapidly during acute ischemia. Bright signal on DWIs.

Question 23

Apparent diffusion coefficient (ADC).

Answer 23

Reflects pure diffusion behavior. Free of underlying T2 contributions (shine through or dark through).

Question 24

Fluid-Attenuated Inversion Recovery (FLAIR) in Ischemia

Answer 24

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.

Question 25

Maximal brain swelling post brain infarction occurs at what days

Answer 25

3 to 7 days postinfarction.

Question 26

Encephalomalacia post brain infarction occurs when

Answer 26

30 to 90 days (1 to 3 months) postinfarction.