Diagnostic Imaging

Question 1

Common locations for arachnoid cysts.

Answer 1

1. Middle cranial fossa.
2. CPA.
3. Suprasellar.
4. Miscellaneous (convexity, quadrigeminal).

Question 2

Diagnostic checklist for arachnoid cysts.

Answer 2

1. Follow CSF on all sequences.
2. Suppresses completely on FLAIR.
3. Shows no restriction on DWI.

Question 3

Classic imaging findings of Dandy-Walker malformation.

Answer 3

1. Cystic dilatation of 4th ventricle – enlarged posterior fossa, superiorly rotated hypoplastic vermis.
2. Torcular-lambdoid inversion.

Question 4

Findings of persistent Blake’s pouch cyst.

Answer 4

1. Tetraventricular hydrocephalus, communicating 4th ventricle and posterior fossa cyst, with or without hypoplasia of both the cerebellar vermis and the medial aspects of the cerebellar hemispheres.

Question 5

Characteristics of Joubert’s anomaly.

Answer 5

1. Episodic hyperpnea, oculomotor apraxia, retinal dystrophy, +/- renal cysts, hepatic fibrosis.
2. Split vermis, bat wing 4th ventricle, mesencephalon is shaped like a molar tooth.

Question 6

Characteristic imaging findings of aqueductal stenosis.

Answer 6

1. Ventriculomegaly of lateral and 3rd ventricles.
2. Corpus callosum thinned, stretched upward.
3. Fornix, internal cerebral veins, 3rd ventricular floor displaced downward.
4. Enlarged rounded optic and infundibular recesses of 3rd ventricle.

Question 7

What are some characteristics of rhombencephalosynapsis?

Answer 7

1. Developmental midline anomaly.
2. Continuity of cerebellar hemispheres with partial or complete absence of vermis.
3. Other midline anomalies include: fusion of inferior/superior colliculi, aqueductal stenosis, absence of septum pellucidum.

Question 8

What does the acronym CRASH syndrome stand for?

Answer 8

CRASH

• callosal hypoplasia
• mental retardation
• adducted thumbs
• spastic paraplegia
• X-linked hydrocephalus

Question 9

What are some abnormalities associated with CRASH syndrome?

Answer 9

1. Absence/diminution of corticospinal tracts, thalamic fusion, collicular fusion, absence of septum pellucidum, corpus callosum dysgenesis.
2. Thin cerebral mantle, malformations of cortical development, hypoplastic white matter.

Question 10

What are some features of Walker-Warburg syndrome?

Answer 10

1. Severe tectal dysgenesis.
2. Aqueductal stenosis.
3. Marked enlargement of lateral > 3rd ventricles.
4. Zigzag brainstem.
5. Small cerebellum.

Question 11

What are some imaging features of callosal dysegnesis or callosal agenesis?

Answer 11

1. On axial CT, lateral ventricles are parallel and separate.
2. Atrium and occipital horns dilated (colpocephaly).
3. ACAs course directly upward in interhemispheric fissure.

Question 12

What is another term for septo-optic dysplasia?

Answer 12

1. Morsier syndrome.

Question 13

What is the pathophysiology of septo-optic dysplasia?

Answer 13

1. Incomplete early morphogenesis of anterior midline structures producing hypoplasia of the optic nerves and possibly optic chiasm and pituitary infundibulum.
2. Septum pellucidum is absent in about half the cases.

Question 14

What are some characteristic imaging features of septo-optic dysplasia?

Answer 14

1. Absent septum pellucidum.
2. Small optic chiasm.
3. Flat-roofed ventricles.
4. Downward-pointing anterior horns.

Question 15

What is Kallman syndrome?

Answer 15

1. Absent olfactory nerves.

2. +/- visual, septal, pituitary abnormalities.

Question 16

Characteristic imaging features of intracranial lipomas?

Answer 16

1. Hyperintense on T1.

2. Hypointense on fat suppression.

Question 17

Common locations of intracranial lipomas?

Answer 17

1. 80% supratentorial, most often in the midline.
2. 40-50% interhemispheric fissure.
3. 15-20% suprasellar.
4. 10-15% tectal region.

Question 18

What can an intracranial lipoma mimic on non-con CT?

Answer 18

1. Intracranial air.

Question 19

Presentation of hypothalamic hamartomas?

Answer 19

1. Precocious puberty.
2. Gelastic seizures (unprovoked laughter).
3. Developmental delay.

Question 20

What is Klippel-Feil syndrome?

Answer 20

1. Congenital fusion of two or more cervical vertebrae.

Question 21

What is the classic triad of Klippel-Feil syndrome?

Answer 21

1. Low posterior hairline.
2. Shortened neck (brevicollis).
3. Limitation of neck motion.

Question 22

What locations are most commonly affected in Klippel-Feil syndrome?

Answer 22

1. C2-3 (50%).

2. C5-6 (33%).

Question 23

What are some associated abnormalities with Klippel-Feil syndrome?

Answer 23

1. Sensorineural hearing loss (30%).
2. GU tract abnormalities (35%).
3. Congenital heart disease (14%).

Question 24

Clinical features of tethered cord syndrome?

Answer 24

1. LE weakness.
2. Sensory deficit.
3. Bladder dysfunction.
4. Cutaneous findings (hypertrichosis, sub-q lipoma).
5. Posterior spina bifida.
6. Muscle atrophy, short limb, ankle deformity.

Question 25

Characteristic imaging features of tethered cord syndrome?

Answer 25

1. Low lying conus (terminating below L2-3 always abnormal at any age). 2. Filum thickened (> 2mm at L5-S1 on axial slice).

Question 26

What is a type 1 split-cord malformation?

Answer 26

1. Two hemicords, each with its own central canal and surrounding pia, each within a separate dural tube separated by a dural-sheathed rigid osseocartilaginous median septum.

Question 27

What is a type 2 split-cord malformation?

Answer 27

1. Two hemicords within a single dural tube, separated by a non-rigid fibrous median septum.

Question 28

Characteristic imaging features of Chiari O?

Answer 28

1. Syringomyelia with low obex position. 2. NO cerebellar tonsillar ectopia. 3. Increased AP diameter of foramen magnum.

Question 29

Diagnostic criteria for Chiari I malformations?

Answer 29

1. Herniation of at least 1 cerebellar tonsil > 5mm or herniation of both tonsils > 3-5 mm below a line connecting the basion with opisthion.

Question 30

Other imaging features of Chiari I malformations?

Answer 30

1. +/- syringomyelia. 2. Pointed tonsils with oblique vertical sulci. 3. Elongated but normally located 4th ventricle.

Question 31

Characteristic imaging features of complex Chiari (aka Chiari 1.5)?

Answer 31

1. Cerebellar tonsillar herniation with low obex. 2. Medullary "bump". 3. +/- syringohydromyelia, ventral cervicomedullary compression. 4. +/- odontoid retroflexion, small posterior fossa, clival anomalies, platybasia.

Question 32

Imaging features of Chiari II malformations?

Answer 32

1. Cerebellum "wraps" around medulla and "towers" through incisura. 2. Beaked tectum. 3. Heart shaped midbrain. 4. Low lying torcula. 5. Cervicomedullary kink.

Question 33

What are some associated anomalies seen with Chiari II?

Answer 33

1. Myelomeningocele (almost 100%). 2. Posterior C1 arch anomalies. 3. Syringohydromyelia. 4. Corpus callosum dysgenesis. 5. Lacunar skull (Luckenschadel).

Question 34

Diagnostic checklist for Chiari III?

Answer 34

1. Occipitocervical encephalocele containing cerebellar +/- brainstem in conjunction with C1-C2 spina bifida.

Question 35

What is a Modic type 1 change?

Answer 35

1. Hypointense on T1. | 2. Hyperintense on T2.

Question 36

What is a Modic type 2 change?

Answer 36

1. Hyperintense on T1. | 2. Isointense on T2.

Question 37

What is a Modic type 3 change?

Answer 37

1. Hypointense on T1 and T2.