Congenital cystic lesions

Dr Ahmed Esawy

•Arachnoid Cyst

Dr Ahmed Esawy

ARACHNIOD VERSUS EPIDERMIOD

arachniod CSF density

No calcification,no enhancment

displace structures

CT

Low signal like CSF MRI T1

high signal like CSF

MRI T2

Low signal like CSF

FLAIR

DARK hypointensity

(free diffusion)

DIFFUSION

BRIGHT marked

hyperintensity

like CSF

ADC

Retrocerebellar,CPA

Dr Ahmed Esawy

T2-weighted sagittal MRI image (see Image 2 for axial view) of the brain

in a 28-year-old woman with an incidental finding of a cisterna ambiens

arachnoid cyst (arrow).

28-year

Dr Ahmed Esawy

Unenhanced CT scan of the head in a 26-year-old man with a history of

seizures since childhood (same patient as Image 4). The scan shows a

large left frontoparietal cyst with a mass effect. Dr Ahmed Esawy

T1-weighted sagittal MRI image of the lumbosacral spine showing

an incidental sacral arachnoid cyst. Dr Ahmed Esawy

T2

DIFFUSION

autopsied brain

ARACHNOID CYSTS

Dr Ahmed Esawy

A)

B.

C.

D.

Arachnoid Cyst

T2-hyperintense mass in the left

cerebellopontine angle (arrow

T1-hypointense mass (arrow)

DW hypointensity in the mass (arrow) ADC map marked hyperintensity

(arrow) similar to that of the CSF Dr Ahmed Esawy

arachnoid cysts

Dr Ahmed Esawy

Arachnoid cyst with enlargement of the calvaria

T2 T1 Non contrast CT

Dr Ahmed Esawy

midline Arachnoid cyst

Causing dilated OH

Coronal gradient echo

FLAIR T1

DW

CT

Dr Ahmed Esawy

28-year-old woman

T2

superior cerebellar cistern arachnoid cyst

Dr Ahmed Esawy

26-year-old man

large left frontoparietal cyst Dr Ahmed Esawy

T2

ARACHNIOD CYST

T1 FLAIR

Dr Ahmed Esawy

• Prenatal coronal T1-left temporal fossa arachnoid cyst.

• post natal coronal T2-left temporal fossa arachnoid cyst.

• postnatal coronal T1-left temporal fossa arachnoid cyst. Dr Ahmed Esawy

Suprasellar arachnoid cyst in a patient with Mowat-Wilson syndrome (includes agenesis of the corpus callosum) and bradycardia from increased intracranial pressure.

The entire fluid collection represents the arachnoid cyst (C) and should not be confused with the third ventricle.

T2

Dr Ahmed Esawy

Differential Diagnosis

• epidermoid cyst

• Chronic subdural hematoma

• porencephalic cyst

Dr Ahmed Esawy

ARACHNIOD VERSUS EPIDERMIOD

epidermiod arachniod Lower density than CSF

May show calcifications

invade structures

CSF density

No calcification,no enhancment

displace structures

CT

LOWER THAN CSF Low signal like CSF MRI T1

HIGHER THAN CSF high signal like CSF

MRI T2

HIGH SIGNAL Low signal like CSF

FLAIR

BRIGHT typical hyperintensity

T2 shine (restricted diffusion)

DARK hypointensity

(free diffusion)

DIFFUSION

DARK lower than that of CSF and equal

to or higher than

that of brain parenchyma

BRIGHT marked

hyperintensity

like CSF

ADC

Away from midlline CPA

Retrocerebellar,CPA

Dr Ahmed Esawy

posterior fossa cystic malformation

destructive lesions

porencephalic cyst

hydranencephaly

multicystic encephalomalacia

Dr Ahmed Esawy

• The normal cisterna magna

characteristically measures 3–8 mm when

measurements are taken in the midsagittal

plane from the posterior lip of the foramen

magnum to the caudal margin of the

inferior vermis

Dr Ahmed Esawy

Isolated mega cisterna magna in a

patient with trisomy 21 transcranial

US /CT

Dr Ahmed Esawy

Dandy-Walker malformation

three criteria • (a) vermian hypoplasia with cephalad rotation of

the vermian remnant,

• (b) cystic dilatation of the posterior fossa communicating with the fourth ventricle, and

• (c) enlargement of the posterior fossa causing an abnormally high tentorium and torcular,

• the latter lying above the level of the lambdoid (ie,torcular-lambdoid inversion)

Dr Ahmed Esawy

Dandy-Walker malformation in a full-term 1-day-old neonate

retrocerebellar collection of CSF (arrowheads). Coronal US scan

shows vermian agenesis and a wide communication with a

"keyhole" appearance (arrowheads) between the cyst posteriorly

and the fourth ventricle (4) anteriorly . The cerebellar

hemispheres (C) are hypoplastic

Magnified transmastoid US scan Dr Ahmed Esawy

posterior fossa cystic malformation

Dandy Walker

Dr Ahmed Esawy

Dandy-Walker malformation in a full-term

1-day-old neonate

Coronal T2-weighted (d) and sagittal T1-weighted (e) MR images show the Dandy-Walker malformation.

Dr Ahmed Esawy

Sagittal T1-weighted image reveals a large posterior fossa fluid collection that extends to the upper

spinal canal. The foramen magnum is enlarged.

There is hypoplasia of the inferior vermis of the cerebellum. Superior vermis present in the midline.

There is significant decrease in the AP dimension of the medulla

Dandy-Walker Variant

with No Separate Fourth

Ventricle

Dr Ahmed Esawy

C. Coronal SPGR image shows asymmetry of the cerebellar

hemispheres; the right cerebellar hemisphere is hypoplastic

Sagittal T1-weighted image demonstrates a large posterior

fossa cyst that communicates with the fourth ventricle

elevating the cerebellar vermis and torcular Herophili

B. Axial T2-weighted

image shows a large CSF-

intensity fluid collection

that expands the posterior

fossa on the right and

communicates in the

midline with the fourth

ventricle (arrow)

Dandy-Walker Variant with Elevation of Torcula

Dr Ahmed Esawy

T1

Axial transmastoid US

T2

Arachnoid cyst

and complex

posterior fossa

malformations

in a full-term 1-

day-old

neonate

Dr Ahmed Esawy

Bilateral supraclinoid internal carotid artery occlusions with intact posterior circulation

Hydranencephaly in new born an extreme example of porencephaly

large cystic space involving the entire supratentorial area bilaterally

No cortical rim

Dr Ahmed Esawy

B. Axial T1-weighted image shows only

portions of temporal lobe and midbrain to

be present.Most of the cranium is filled

with fluid

Hydranencephaly with Microcephaly

A. Sagittal T1-weighted image

shows portions of frontal lobes,

midbrain and cerebellum to be

present Dr Ahmed Esawy

d

Hydranencephaly with increasing head size

A. Noncontrast CT through the

temporal lobes reveals normal-

appearing lower temporal lobes with

abnormal CSF collection frontally

B. CT image reveals that CSF replaces

the hemispheric brain tissue with a thin

residual midline and occipital lobe brain

C. Sagittal T1-weighted image

shows that the areas supplied by

posterior cerebral artery are

preserved

D. T2-weighted image shows normal

lower medial temporal and occipital

lobes. The thalami are not fuse

E. T2-weighted image shows

that CSF occupies most of the

space normally filled with brain

F. Coronal SPGR image shows also that areas

supplied by the posterior cerebral artery are

preserved. The falx (arrow) is partially normal

Dr Ahmed Esawy

B. Axial T2-weighted image shows the brainstem and cerebellum to be present

C. Axial T2-weighted image through the expected hemispheres shows a portion of

residual temporal lobe on the left

A. Sagittal T2-weighted image demonstrates

fluid filling most of the cranium in the

expected location of the cerebral

hemispheres. Only the cerebellum and part

of the thalami are present

Hydranencephaly with increasing head size

Dr Ahmed Esawy

PORENCEPHALIC CYSTS

• congenital or acquired cavities within the cerebral hemisphere

• cortical or subcortical

• unilateral or bilateral .

• The location often corresponds to territories supplied by the cerebral arteries .

• Congenital porencephalic cysts originate from a fetal or perinatal encephaloclastic process that results from intrauterine vascular or infectious injury .

• Acquired cysts are secondary to injury later in life and are usually secondary to trauma, surgery, ischemia, or infection

Dr Ahmed Esawy

Coronal T1-MR

enlarged left temporal horn (black arrow) that communicates with peripherally located porencephalic cyst (white arrows). Cyst extends to the brain surface

Dr Ahmed Esawy

Differential Diagnosis

• arachnoid cyst (extra-axial)

• schizencephaly

• (ependymal cyst) intraventricular with normal surrounding brain tissue (

• encephalomalacia

• hydranencephaly

Dr Ahmed Esawy

1-day-old term infant

Porencephaly (no communication with the ventricles)

CT no C

calcifications along the margins of the cavity (arrowheads). These are probably sequelae of a remote infarct in the distribution of the middle cerebral artery.

Dr Ahmed Esawy

Porencephaly in a 26-week gestation premature neonate

Dr Ahmed Esawy

CT scan at the age of 13 years showing the porencephalic

cyst in left cerebral hemisphere.

Dr Ahmed Esawy

• the midline cavities and their positions in the sagittal plane (top) and coronal plane (bottom).

• supratentorial cystic lesions in a periventricular location,

Dr Ahmed Esawy

28-week gestation neonate

Dr Ahmed Esawy

Cavum veli interpositium.

33 weeks of gestation

Dr Ahmed Esawy

Differential diagnosis Periventricular Location

• periventricular leukomalacia (PVL),

• connatal cyst (CC),

• subependymal cyst (SC)

• anatomic locations. Dr Ahmed Esawy

• Connatal cysts in a 30-week gestation preterm infant. just lateral to the frontal horn and body of the lateral ventricle.

connatal cysts are coarctation of the lateral ventricles and frontal horn cysts sequelae of ischemic insults

Dr Ahmed Esawy

Bilateral connatal cysts in a 3-week-old full-term neonate

along superolateral angles of the lateral ventricles (arrows).

Dr Ahmed Esawy

Subependymal Cysts

• acquired, posthemorrhagic cyst

• congenital and is related to germinolysis.

Dr Ahmed Esawy

Acquired subependymal cyst due to an

evolving subependymal hemorrhage

caudothalamic groove

T2 T1

Dr Ahmed Esawy

Open lip schizencephaly (type II)

T1

T2

T2

T2 FLAIR

Dr Ahmed Esawy

Periventricular Leukomalacia

• Periventricular leukomalacia (PVL) refers to white matter necrosis in a characteristic distribution.

• The distribution pattern is dorsal and lateral to the external angles of the lateral ventricles

• involves particularly the centrum semiovale and the optic (trigone and occipital horns) and acoustic (temporal horn) radiations .

• PVL most frequently occurs in premature infants of less than 32 weeks gestation due to the unique anatomic features of the brain at this age.

Dr Ahmed Esawy

• Extensive cystic PVL in a 29-week gestation premature neonate. extensive multiseptate cystic areas located superiorly to the frontal horns (arrows). There is ex vacuo dilatation of the ventricles secondary to white matter loss.

Dr Ahmed Esawy

Unilateral periventricular leukomalacia

Gray matter indents the ventricle wall (arrow)

due to severe white matter loss on right.

Corpus callosum is thin. The right hemisphere

is smaller than the left.

Typical undulation of ventricular wall is present

Dr Ahmed Esawy

B. DW image shows hypointensity

in right hemisphere cystic lesions

Multicystic Encephalomalacia

A.T1-weighted image shows a thin corpus callosum

Dr Ahmed Esawy

E. T2-weighted image

shows diffuse hyperintense

cysts throughout the right

hemisphere that is smaller

C. Axial FLAIR image

reveals small right

hemisphere and multiple

CSF containing spaces with

dilated lateral ventricle

D. Coronal FLAIR image confirms

the encephalo-malacia and ex

vacuo atrophy displacing the

midline to right

Multicystic Encephalomalacia

Dr Ahmed Esawy

Multicystic Encephalomalacia

F. T1-weighted image shows

hypointensity in the right cerebral

hemisphere. This is consistent with an

area of encephalomalacia and gliosis due

to a prior insult such as infarct or

infection. Minimal hyperintensity is noted

in the area of encephalomalacia

consistent with mineralization

H. CT at the age of 3years shows

multicystic encephalomalacia with

small right hemicranium

G. T1-FLAIR image shows multiple

CSF containing cysts. The thin cortex

is better appreciated in this sequence

Dr Ahmed Esawy

Schizencephaly with bilateral clefts in a 36-

week gestation preterm infant.

Dr Ahmed Esawy

Severe obstructive

hydrocephalus due to

aqueductal stenosis.

large fluid-filled space

posteriorly which

represents a markedly

dilated lateral ventricle

that simulates a large

cyst.

choroid plexus (CP) • thalami (T)

Dr Ahmed Esawy

Holoprosencephaly spectrum disorder in a newborn.

a) Midline sagittal US scan shows a large

monoventricle (arrows). The third and

fourth ventricles are normal

(b) Coronal US scan shows an absent septum pellucidum, the large monoventricle (arrows), and partially fused thalami (T).

Dr Ahmed Esawy

(b) Sagittal T2-weighted MR image shows

the shieldlike appearance of forebrain

structures and the monoventricle

(arrowheads).

A-Axial T2-weighted MR image shows

partial fusing (arrowheads) of the thalami

(T) and the large monoventricle posteriorly

Holoprosencephaly spectrum disorder in a newborn. Dr Ahmed Esawy

Sagittal T1-weighted image shows hypoplastic cerebellar hemisphere (arrow),

small brainstem and a large posterior CSF space. There is also a prominent CSF

space anterior to the pons. Corpus callosum is thin and splenium absent

Chiari III

Dr Ahmed Esawy

Holoprosencephaly/ aqueductal

stenosis

• The key is in the appearance of the thalami and

third ventricle: holoprosencephaly exhibits

fused thalami and an absent third

ventricle,while aqueductal stenosis will show

splayed thalami and a dilated third ventricle

Dr Ahmed Esawy

Left frontal intraparenchymal hematoma in a newborn with

increasing thrombocytopenia

T1

Spontaneous Intracranial Hematoma

Dr Ahmed Esawy

Spontaneous intracranial hematoma in a 2-month-old infant with an inherited thrombophilic disorder.

Dr Ahmed Esawy

Temporal lobe cysts and fetal

alcohol syndrome

Parasagittal T1-

T2-bitemporal intraparenchymal cysts

(arrows).

FLAIR

Dr Ahmed Esawy

Temporal lobe cysts and fetal

alcohol syndrome MRS

Dr Ahmed Esawy