Diagnostic Imaging Flashcards
Common locations for arachnoid cysts.
- Middle cranial fossa.
- CPA.
- Suprasellar.
- Miscellaneous (convexity, quadrigeminal).
Diagnostic checklist for arachnoid cysts.
- Follow CSF on all sequences.
- Suppresses completely on FLAIR.
- Shows no restriction on DWI.
Classic imaging findings of Dandy-Walker malformation.
- Cystic dilatation of 4th ventricle – enlarged posterior fossa, superiorly rotated hypoplastic vermis.
- Torcular-lambdoid inversion.
Findings of persistent Blake’s pouch cyst.
- 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.
Characteristics of Joubert’s anomaly.
- Episodic hyperpnea, oculomotor apraxia, retinal dystrophy, +/- renal cysts, hepatic fibrosis.
- Split vermis, bat wing 4th ventricle, mesencephalon is shaped like a molar tooth.
Characteristic imaging findings of aqueductal stenosis.
- Ventriculomegaly of lateral and 3rd ventricles.
- Corpus callosum thinned, stretched upward.
- Fornix, internal cerebral veins, 3rd ventricular floor displaced downward.
- Enlarged rounded optic and infundibular recesses of 3rd ventricle.
What are some characteristics of rhombencephalosynapsis?
- Developmental midline anomaly.
- Continuity of cerebellar hemispheres with partial or complete absence of vermis.
- Other midline anomalies include: fusion of inferior/superior colliculi, aqueductal stenosis, absence of septum pellucidum.
What does the acronym CRASH syndrome stand for?
CRASH
- callosal hypoplasia
- mental retardation
- adducted thumbs
- spastic paraplegia
- X-linked hydrocephalus
What are some abnormalities associated with CRASH syndrome?
- Absence/diminution of corticospinal tracts, thalamic fusion, collicular fusion, absence of septum pellucidum, corpus callosum dysgenesis.
- Thin cerebral mantle, malformations of cortical development, hypoplastic white matter.
What are some features of Walker-Warburg syndrome?
- Severe tectal dysgenesis.
- Aqueductal stenosis.
- Marked enlargement of lateral > 3rd ventricles.
- Zigzag brainstem.
- Small cerebellum.
What are some imaging features of callosal dysegnesis or callosal agenesis?
- On axial CT, lateral ventricles are parallel and separate.
- Atrium and occipital horns dilated (colpocephaly).
- ACAs course directly upward in interhemispheric fissure.
What is another term for septo-optic dysplasia?
- Morsier syndrome.
What is the pathophysiology of septo-optic dysplasia?
- Incomplete early morphogenesis of anterior midline structures producing hypoplasia of the optic nerves and possibly optic chiasm and pituitary infundibulum.
- Septum pellucidum is absent in about half the cases.
What are some characteristic imaging features of septo-optic dysplasia?
- Absent septum pellucidum.
- Small optic chiasm.
- Flat-roofed ventricles.
- Downward-pointing anterior horns.
What is Kallman syndrome?
- Absent olfactory nerves.
2. +/- visual, septal, pituitary abnormalities.
Characteristic imaging features of intracranial lipomas?
- Hyperintense on T1.
2. Hypointense on fat suppression.
Common locations of intracranial lipomas?
- 80% supratentorial, most often in the midline.
- 40-50% interhemispheric fissure.
- 15-20% suprasellar.
- 10-15% tectal region.
What can an intracranial lipoma mimic on non-con CT?
- Intracranial air.
Presentation of hypothalamic hamartomas?
- Precocious puberty.
- Gelastic seizures (unprovoked laughter).
- Developmental delay.
What is Klippel-Feil syndrome?
- Congenital fusion of two or more cervical vertebrae.
What is the classic triad of Klippel-Feil syndrome?
- Low posterior hairline.
- Shortened neck (brevicollis).
- Limitation of neck motion.
What locations are most commonly affected in Klippel-Feil syndrome?
- C2-3 (50%).
2. C5-6 (33%).
What are some associated abnormalities with Klippel-Feil syndrome?
- Sensorineural hearing loss (30%).
- GU tract abnormalities (35%).
- Congenital heart disease (14%).
Clinical features of tethered cord syndrome?
- LE weakness.
- Sensory deficit.
- Bladder dysfunction.
- Cutaneous findings (hypertrichosis, sub-q lipoma).
- Posterior spina bifida.
- Muscle atrophy, short limb, ankle deformity.
Characteristic imaging features of tethered cord syndrome?
- Low lying conus (terminating below L2-3 always abnormal at any age).
- Filum thickened (> 2mm at L5-S1 on axial slice).
What is a type 1 split-cord malformation?
- 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.
What is a type 2 split-cord malformation?
- Two hemicords within a single dural tube, separated by a non-rigid fibrous median septum.
Characteristic imaging features of Chiari O?
- Syringomyelia with low obex position.
- NO cerebellar tonsillar ectopia.
- Increased AP diameter of foramen magnum.
Diagnostic criteria for Chiari I malformations?
- Herniation of at least 1 cerebellar tonsil > 5mm or herniation of both tonsils > 3-5 mm below a line connecting the basion with opisthion.
Other imaging features of Chiari I malformations?
- +/- syringomyelia.
- Pointed tonsils with oblique vertical sulci.
- Elongated but normally located 4th ventricle.
Characteristic imaging features of complex Chiari (aka Chiari 1.5)?
- Cerebellar tonsillar herniation with low obex.
- Medullary “bump”.
- +/- syringohydromyelia, ventral cervicomedullary compression.
- +/- odontoid retroflexion, small posterior fossa, clival anomalies, platybasia.
Imaging features of Chiari II malformations?
- Cerebellum “wraps” around medulla and “towers” through incisura.
- Beaked tectum.
- Heart shaped midbrain.
- Low lying torcula.
- Cervicomedullary kink.
What are some associated anomalies seen with Chiari II?
- Myelomeningocele (almost 100%).
- Posterior C1 arch anomalies.
- Syringohydromyelia.
- Corpus callosum dysgenesis.
- Lacunar skull (Luckenschadel).
Diagnostic checklist for Chiari III?
- Occipitocervical encephalocele containing cerebellar +/- brainstem in conjunction with C1-C2 spina bifida.
What is a Modic type 1 change?
- Hypointense on T1.
2. Hyperintense on T2.
What is a Modic type 2 change?
- Hyperintense on T1.
2. Isointense on T2.
What is a Modic type 3 change?
- Hypointense on T1 and T2.
