C.N.S.Vascular Malformations

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Vascular Malformations(i) Malformations with AV shunts :a) AVMb) Dural AVFc) Pial AVF(ii) Malformations without AV shunts :a) Cavernous Malformationb) Venous Malformationsc) Capillary Telangiectasiad) Moyamoya Disease

(i) Malformations with AV shunts :a) AVMb) Dural AVFc) Pial AVF

a) Arteriovenous Malformations (AVM) :1-Definition2-Incidence3-Clinical Picture4-Types5-Cerebrofacial Arterio-venous Metameric Syndrome

(CAMS)6-Proliferative Angiopathy7-Radiographic Features8-Grading System9-Complications10-Treatment Options

1-Definition :-An AVM is a congenital high-flow vascular

malformation consisting of directly connecting arteries & veins without an intervening capillary bed

-The transition between artery and vein can take place via a so-called nidus (i.e. a tangle of abnormal vessels located in the brain parenchyma)

2-Incidence :-Peak age is 20 to 40 years-98% of AVM are solitary-Occurs intra-axially & 85 % are supratentorial-Multiple lesions in various syndromes, Osler-

Weber-Rendu and Wyburn-Mason

3-Clinical Picture :-One or combination of hemorrhage (usually

parenchymal hemorrhage, rarely subarachnoid, 40 %), seizures (30 %), neurological deficit or headache (20 %)

-Aneurysms of the feeding arteries or intra-nidal arteries are often seen which predispose to bleeding

4-Types :a) Parenchymal, 80% (ICA and vertebral artery

supply, congenital lesions)b) Dural, 10% (ECA supply, mostly acquired

lesions)c) Mixed, 10%

5-Cerebrofacial Arterio-venous Metameric Syndrome (CAMS) :

a) Definitionb) Typesc) Diagnosis

a) Definition :-CAMS (also known as Wyburn-Mason

syndrome or Bonnet-Dechaume-Blanc disease)

b) Types :1-CAMS type 1 :-Involves the medial prosencephalon and will

manifest with AVMs located at the corpus callosum, hypothalamus (hypophysis) and nose

2-CAMS type 2 :-Involves the lateral prosencephalon with AVMs at

the occipital lobe and optic tract including the thalamus, retina and maxilla

CAMS type 2 in a 10-year-old girl who presented with a 1-year history of progressive right hemiparesis , chemosis and proptosis of the left eye were also noted (a, b) CT+C obtained at the level of the orbits (a) and brain (b) show an enhancing vascular lesion at the left basal ganglia , the lesion exerts a mass effect on the left lateral ventricle , in addition , serpiginous structures are seen surrounding the optic nerve , (c) Lateral LT ICA angiogram shows a proliferative type brain AVM nidus at the basal ganglia , another smaller AVM is noted surrounding the left optic nerve (solid arrow) , there is early venous drainage anteriorly into the basal frontal cortical veins (arrowheads) and posteriorly into the basal vein of Rosenthal (open arrow)

CAMS type 2 in a 7-year-old girl who presented with recurrent episodes of bleeding from the gum due to eruption of a left molar , (a) Coronal CT scan (bone window) reveals an osteolytic lesion within the alveolar ridge of the left maxilla , (b, c) Left external (b) and internal (c) carotid angiograms show a facial osseous AVM supplied by branches of the internal maxillary and transverse facial arteries and draining into an intraosseous venous pouch (arrow in b) , this finding corresponds to the osteolytic lesion seen in a and proved to be the source of the patient’s bleeding , an AVM of the left optic nerve is also noted, thereby allowing the diagnosis of CAMS type 2

3-CAMS type 3 :-Involves the rhombencephalon and affected

patients will have AVMs at the cerebellum, pons and mandible

c) Diagnosis :-The most important clue to the diagnosis of CAMS

is the presence of multiple AVMs in both the brain parenchyma and the facial region

6-Proliferative Angiopathy :a) Incidenceb) Clinical Picturec) Radiographic Features

a) Incidence :-Cerebral proliferative angiopathy, previously

known as diffuse nidus type AVM, is present in an estimated 2%-4% of all brain AVMs

-There is a female predilection of 2:1 with a rather young mean patient age (20 years)

b) Clinical Picture :-Progressive neurologic deficits, transient

ischemic attacks, seizures and headaches are the common presenting symptoms with hemorrhage being extremely rare

c) Radiographic Features :1-CT & MRI2-Catheter Angiography

1-CT & MRI :-The typical MR imaging and CT findings include

a proliferative type nidus in which normal brain parenchyma is interspersed between the abnormal vessels

-Often an entire lobe or even brain hemisphere is affected

(a) PD , (b) T1+C show multiple flow voids and contrast-enhanced tubular structures representing a large vascular lesion that involves the entire right cerebral hemisphere , the normal brain parenchyma is interspersed between the abnormal vessels

2-Catheter Angiography :-The arterial feeder vessels tend to be of normal

size or only moderately enlarged, associated stenosis of the feeder vessels are often identified

-There is extensive transdural supply to normal and abnormal brain tissue through branches of the ECA

-The lack of clear early venous drainage on dynamic images is the key to differentiating this disease from classic brain AVM

(a) AP RT ICA angiogram shows relatively normal-sized MCA branches and lack of early venous drainage , findings that confirm the diagnosis of proliferative angiopathy , stenosis of the proximal M2 segment of the right MCA just distal to the MCA bifurcation is also noted (arrow) , (b) Lateral RT ECA angiogram shows an extensive transdural supply to the right cerebral hemisphere via the branches of the middle meningeal artery

7-Radiographic Features :a) CTb) MRIc) Catheter Angiography

a) CT :-Hyperdense enlarged serpiginous vessels-Often speckled calcification (25 %)-Enhance strongly

Left occipital arteriovenous malformation (AVM) with multiple calcified phleboliths and numerous hyperattenuating vascular channels

CT+C shows a tangle of intensely enhancing tubular structures embedded in the left parietal lobe , a finding that is compatible with a nidus , hyperattenuation representing intraventricular hemorrhage is noted in the ventricles

b) MRI :-Serpiginous black flow voids-May be evidence of local atrophy and gliosis (as a

result of vascular steal and ischemia) or previous hemorrhage

-AVM replaces but does not displace brain tissue (i.e. mass effect is uncommon) unless complicated by hemorrhage and edema

-Edema occurs only if there is recent hemorrhage or venous thrombosis with infarction

-There are usually adjacent changes to the adjacent brain including gliosis (T2 prolongation), dystrophic calcification & blood products (blooming T2* gradient imaging), the gliosis / encephalomalacia or mineralization seen in the adjacent brain is due to alteration in vascular flow from the AVM

T1 shows large occipital arteriovenous malformation (AVM) with parasagittal flow void

T2 showing numerous flow voids

c) Catheter Angiography :-Gold standard for assessment of morphology

and nidal architecture including presence of associated arterial or venous aneurysms (10 %), varices and stenosis

-The diagnostic criteria include :1-Nidus embedded within the brain parenchyma 2-Early venous drainage, if the veins are seen in

the arterial phase

Lateral left internal carotid angiogram reveals a glomerular type nidus in a cortical location supplied mainly by the posterior parietal and angular branches of the left MCA with early drainage into a left parietal cortical vein , findings that confirmed the diagnosis of a brain AVM

8-Grading System : (Spetzler's Criteria)

0 1 2 3

Eloquence No Yes - -

Draining vein Superficial Deep - -

Size - < 3 cm

3-6 cm > 6 cm

-Higher score is associated with higher chance of hemorrhage

-Other factors associated with poorer prognosis/higher risk of hemorrhage :

1-Intranidal aneurysm2-Aneurysm in the circle of Willis3-Aneurysm in arterial feeder4-Venous stasis

-Eloquence of adjacent brain :a) Eloquence brain :-Sensorimotor, language, visual cortex,

hypothalamus, thalamus, brain stem, cerebellar nuclei or regions directly adjacent to these structures

b) Non-eloquence brain :-Frontal and temporal lobe, cerebellar

hemispheres

9-Complications :a) Hemorrhage (parenchymal > SAH >

intraventricular)b) Seizuresc) Cumulative risk of hemorrhage is

approximately 3 % per year

10-Treatment Options :a) Surgeryb) Endovascular embolizationc) Radiosurgery d) Conservative management

a) Surgery :-Patients with smaller and cortical-based brain

AVMs are likely to benefit most from surgical resection

b) Endovascular embolization :-There are no real contraindications for

endovascular therapy, however, the cure rate with embolization alone is relatively low ( 10%-20% ) except in small lesions

c) Radiosurgery :-Radiosurgery has a high cure rate with

relatively low complication rates-However, its major limitation is that radiation is

slow to take effect, it may be up to 2 years before any shrinkage of the brain AVM is seen

d) Conservative Management :-Is typically used when the risk posed by

treatment is too high such as in large brain AVMs or in asymptomatic patients who are believed to have a low risk of future hemorrhage

b) Dural Arteriovenous Fistula (DAVF) :1-Incidence2-Etiology3-Clinical Picture4-Location5-Radiographic Features6-Classification7-Caroticocavernous fistula

1-Incidence :-Dural AVFs are abnormal connections between arteries that

would normally feed the meninges bone or muscles but not the brain and small venules within the dura mater

-Acquired lesions presenting in older population (50-70 years) compared to AVM (20-40 years)

2-Etiology :-Occur following damage to venous structures (post-thrombosis,

surgery & trauma)-They typically have multiple feeders and are usually acquired,

most frequently from as a result of neovascularisation induced by previously thrombosed dural venous sinus (typically transverse sinus)

-Therefore supply is typically from the same branches that supply meningeal arterial supply :

a) Supratentorial : Middle meningeal artery (ECA)b) Anterior cranial fossa : Ethmoidal branches of

the ophthalmic artery (from ICA)c) Cavernous sinus : Dural branches from the ICA

and accessory meningeal branch of the maxillary artery (via foramen ovale), branch of ECA

d) Posterior cranial fossa :Dural branches from the vertebral arteries, branches from occipital and ascending pharyngeal arteries, branches of ECA

3-Clinical Picture :-Symptoms & signs secondary to arterialization of venous

system :a) Bruitb) Venous hypertensionc) Pulsatile tinnitus (if primary involvement is sinuses)d) Hemorrhagee) Focal neurologyf) Seizuresg) Caroticocavernous fistula may give rise to proptosis &

chemosis

4-Location :a) Transverse/ sigmoid sinus : Most commonb) Cavernous sinusc) SSSd) Straight Sinuse) Other venous sinusesf) Anterior cranial fossa : Typically only ICA supply

due to meningeal supply of this regiong) Tentorium

5-Radiographic Features :a) CT & MRIb) Catheter Angiography

a) CT & MRI :-Often normal unless complications (e.g.

hemorrhage, enlargement of cavernous sinus and superior ophthalmic veins if caroticocavernous fistula)

-Dilated cortical veins (a condition referred to as a pseudophlebitic) which manifest as abnormal enhancing tubular structures or flow voids within the cortical sulci with no true nidus within the brain parenchyma

Borden type 2 dural AVF in a 45-year-old woman who presented with sudden loss of consciousness , (a) CT without contrast shows a left temporo-occipital hematoma with intraventricular hemorrhage , (b) T2 shows multiple flow void vascular structures along the cortical sulci of both occipital regions , there is white matter edema with T2 hyperintensity in the left occipital lobe with evidence of a resolving hematoma , no nidus can be identified , (c) Left internal maxillary angiogram reveals a dural AVF in the left transverse sinus supplied by branches of the left middle meningeal artery , note the associated thrombosis of the proximal and distal parts of the transverse sinus creating an “isolated pouch” and thereby causing reflux from the shunt into the cortical veins

-Hypoattenuation of the white matter at CT or hyperintense T2 signal at MR imaging indicates venous congestion or infarction which may eventually lead to venous hemorrhage

-Focal enhancement of these areas may also be observed as a sign of chronic venous ischemia

-Curvilinear subcortical calcifications can be seen at CT in patients with long-standing cortical venous reflux, possibly due to chronic venous congestion

c) Catheter Angiography :-Still gold standard for diagnosis and

demonstration of morphology on which classification and treatment planning based

-Demonstrate early venous filling, the contribution from external carotid artery branches (rather than pial vessels) and shunt location

6-Classification :a) Cognard classificationb) Borden classification

a) Cognard classification :-Correlates venous drainage patterns with increasingly

aggressive neurological clinical courseType I : Confined to sinus wall, typically after thrombosisType II :IIa : Confined to sinus with reflux (retrograde) into sinus

but not cortical veinsIIb : Drains into sinus with reflux (retrograde) into cortical

veins (10-20% hemorrhage)

Type III : Drains direct into cortical veins (not into sinus), 40% hemorrhage

Type IV : Drains direct into cortical veins (not into sinus) with venous ectasia, 65% hemorrhage

Type V : Spinal perimedullary venous drainage, associated with progressive myelopathy

b) Borden classification :1-Type 1 : -DAVF drainage into a dural venous sinus or

meningeal vein with normal anterograde flow- Usually benign clinical behavior-Equivalent to Cognard type I and II

2-Type 2 :-Anterograde drainage into dural venous sinus and

onwards but retrograde flow occurs into cortical veins

-May present with hemorrhage-Equivalent to Cognard type IIb and IIa+b3-Type 3 :-Direct retrograde flow of blood from the fistula into

cortical veins causing venous hypertension with a risk of hemorrhage

-Equivalent to Cognard type III, IV and V

7-Caroticocavernous Fistula :a) Definitionb) Etiologyc) Clinical Pictured) Classificatione) Radiographic Features

a) Definition :-Represent abnormal communication between

the carotid circulation and the cavernous sinus

b) Etiology :-Direct CCFs are often secondary to trauma,

most commonly seen in the young male patients, presentation is acute and symptoms develop rapidly

-In contrast, indirect CCFs have a predilection for the postmenopausal female patient and the onset of symptoms is often insidious

c) Clinical Picture :1-Pulsatile exophthalmos / proptosis : 75 % 2-Chemosis and subconjunctival hemorrhage3-Progressive visual loss : 25-32 % 4-Pulsatile tinnitus (usually objective)5-Raised intracranial pressure6-subarachnoid hemorrhage, intracerebral

hemorrhage, otorrhagia, epistaxis : 2.5-8.5 %

d) Classification :-It can be broadly classified into two main types1-Direct : Direct communication between intra-

cavernous ICA and cavernous sinus 2-Indirect : Communication exists via branches

of the carotid circulation (ICA or ECA)

-Another method is to classify according to four main types :

Type A : Direct connection between the intracavernous ICA and CS

Type B : Dural shunt between intracavernous branches of the ICA and CS

-Type C : Dural shunt between meningeal branches of the ECA and CS

-Type D : B + C

*Direct : type A-A direct fistula is due to a direct communication

between the intracavernous ICA and the cavernous sinus

-There are a number of causes, however aneurysm rupture and trauma are by far the most common

*Indirect : types B, C & D-Indirect fistulas are due to communication by

multiple branches between the ICA / ECA and CS-The are most frequent are type C, with meningeal

branches of the ECA forming the fistula-They are postulated to occur secondary to

cavernous sinus thrombosis with revascularization

-Other predisposing factors appear to be pregnancy, surgical procedures in the region & sinusitis

e) Radiographic Features :1-CT2-MRI3-Catheter Angiography

1-CT :-Proptosis-Enlargement of cavernous sinus, enlarged

superior ophthalmic veins -Extra ocular muscles may be enlarged-Orbital edema-May show SAH / ICH from ruptured cortical

vein

2-MRI :-Findings of CCFs include a dilated CS with multiple signal

intensity void structures that are associated with proptosis and an enlarged superior ophthalmic vein

-On gradient-echo images, these flow voids shows high signal intensity

-The presence of flow-related enhancement in the CS on MRA suggests the diagnosis in the right clinical setting

-Other supporting findings are a dirty appearance of the retro-orbital fat and enlargement of the extraocular muscles, due to the presence of intracavernous communications, very high-flow fistulas may result in enlargement of both CSs

ICA to a CS fistula , axial source image from an MRA shows flow-related enhancement in the medial (arrow) left CS from a direct-type fistula

MRA shows an enlarged superior ophthalmic vein (arrow)

MRA shows a right carotid cavernous fistula (arrow)

3-Catheter Angiography :-Rapid shunting from ICA to CS-Enlarged draining veins-Retrograde flow from CS, most commonly into

the ophthalmic veins

c) Pial AVF :1-Definition2-Incidence3-Location4-Radiographic Findings

1-Definition :-Consist of a direct fistulous communication

between a pial artery and a vein without any intervening nidus

-They differ from dural AVFs in that they derive their arterial supply from pial or cortical arteries and are not located within the dura mater

2-Incidence :-Pial AVFs are more commonly encountered in

children and are frequently associated with hereditary hemorrhagic telangiectasia

3-Location :-Pial AVFs are located on the surface of the brain,

are often high flow lesions and in most instances are associated with dilated venous pouches

4-Radiographic Findings :-Clues to the diagnosis of pial AVFs at cross

sectional imaging include the presence of :a) Dilated vessels, mainly at the brain surfaceb) Asymmetric dilatation of the pial feeding artery,

either the MCA, ACA or PCA, which is best seen at the level of the circle of Willis

-These findings can be used to differentiate pial AVFs from dural AVFs and may be accompanied by dilated venous pouches outside the brain parenchyma

Pial AVF in a 1-week-old neonate who presented with congestive heart failure , the patient had a family history of hereditary hemorrhagic telangiectasia , (a, b) Axial T2 reveal enlargement of the right MCA at the level of the circle of Willis (arrow in a) and a large dilated vascular structure in the right perisylvian region (arrowhead in b) , findings that are suggestive of a venous pouch , the upper portion of another large flow void structure is also seen in the posterior fossa , no nidus can be identified , (c) Lateral RT ICA angiogram reveals a high-flow fistula between an MCA branch and a large venous pouch (arrowhead) , retrograde flow of contrast material into the basilar artery confirms the presence of another high-flow fistula (arrows) from the posterior inferior cerebellar artery , the high-flow fistulas and venous pouches are typical findings in a patient with hereditary hemorrhagic telangiectasia

Pial AVF with venous pouches and venous congestion in a 7-year-old boy who presented with headaches , the patient had a family history of nosebleeds and mucosal telangiectasias suggestive of hereditary hemorrhagic telangiectasia , (a,b) T2 reveal large dilated vascular structures in the right perisylvian region suggestive of venous pouches with enlargement of the right MCA relative to the left side (arrow in b) and no identifiable nidus , findings that are compatible with a pial AVF , the hyperintense T2 signal of the white matter at the right frontal lobe (arrow in a) is suggestive of venous congestion , (c) Lateral RT ICA angiogram reveals a high-flow fistula between an MCA branch and large venous pouches

(ii) Malformations without AV shunts :a) Cavernous Malformationb) Venous Malformationsc) Capillary Telangiectasiad) Moyamoya Disease

a) Cavernous Malformation :1-Definition2-Incidence3-Location4-Clinical Picture5-Radiographic Findings

1-Definition :-Cavernous angioma (Cavernoma) -Dilated endothelial cell-lined spaces with no

normal brain within lesion-Usually detectable because cavernous

malformation contains blood degradation products of different stages

2-Incidence :-All age group-60-80 % multiple (may be familial)-Often associated with an adjacent developmental

venous anomaly (DVA), there is increased risk of bleeding if a DVA is present, however, the DVA itself doesn’t have any bleeding risk

-When multiple, cavernous malformations represent an inherited disorder called familial cavernomatosis

3-Location :-80% supratentorial-Occur anywhere in CNS, common in Pons

4-Clinical Picture :-Small hemorrhages (usually not associated with

large hemorrhages)-Seizures-Headache secondary to occult hemorrhage

5-Radiographic Findings :a) CTb) MRIc) Catheter Angiography

a) CT :-Isodense / Hyperdense (lesion due to

calcification)-Range in size from tiny (single focus of

susceptibility artifact) to giant

b) MRI :-T2 : Popcorn lesion : bright lobulated center with

black (hemosiderin) rim-Subacute hemorrhage and degraded blood

products within the lesion produce a halo of signal hyperintensity around the lesion on T1-weighted images, a useful finding for differentiating cavernous malformations from hemorrhagic tumors and other intracranial hemorrhages

-Always obtain susceptibility sequences to detect coexistent smaller lesions

Cavernoma in the postcentral gyrus on T1 , T2 and SWI , notice popcorn appearance and blooming artifact

T2 & T2* gradient echo show multiple cavernomas , notice the popcorn appearance with peripheral rim of hemosiderin on the T2 , the lesions are almost completely black on the gradient echo due to blooming artefacts , T2* and susceptibility weighted imaging (SWI) markedly increase the sensitivity of MRI to detect small cavernomas , the five black dots in the left cerebral hemisphere on the T2* are also cavernomas and are not visible on the T2WI

(a) Axial T2 shows a large left parietal mass that resembles a popcorn ball with a hypointense hemosiderin rim (arrows) and loculated hyperintense compartments

(b) Axial T1 at the same level shows multiple high signal intensity compartments in the lesion , findings suggestive of subacute hemorrhage , a faint halo of high signal intensity also is visible around the lesion (arrowheads)

Cavernous malformation & associated DVA , T1+C show a hypointense , centrally hyperintense nonenhancing cavernous malformation (yellow arrow) in the left cerebellar hemisphere , directly superior to the cavernoma (b) is an enhancing vascular structure with caput medusa morphology (red arrow) representing a DVA

Giant cavernous malformation (a) CT without contrast shows a hyperattenuating complex mass (arrows) in the RT fronto-temporal lobe , (b) T1 shows the mass is predominantly cystic & hyperintense (representing blood products) , (C) FLAIR shows that the intracystic contents are primarily hyperintense , there is a complete low signal hemosiderin ring surrounding the lesion (red arrows) , there is mild surrounding edema , (d) T1+C shows no appreciable enhancement

c) Catheter Angiography :-Usually normal

b) Venous Malformations :1-Developmental Venous Anomaly2-Vein of Galen Malformation3-Venous Varix

1-Developmental Venous Anomaly (Venous Angioma) :

a) Definitionb) Radiographic Features

a) Definition :-DVA is an abnormal vein that provides functional

venous drainage to normal brain -Venous angiomas per se do not hemorrhage but

are associated with cavernous malformation (30%) which do bleed

-DVA is a DO NOT Touch lesion, if resected, the patient will suffer a debilitating venous infarct, the DVA must be preserved if an adjacent cavernous malformation is resected

b) Radiographic Features :1-CT2-MRI3-Catheter Angiography

1-CT :-Only enhanced scans may show linear vein

draining to ependymal lining of ventricle or cortex with inverse umbrella-shaped (caput medusa) leash of vessels draining towards anomalous veins

2-MRI :-Medusa head or large transcortical vein best

seen on spin-echo images or after administration of gadolinium

-Location in deep cerebellar white matter or deep cerebral white matter

-Adjacent to the frontal horn (most common site)

T1+C

DVA & a tiny cavernous malformation , (a) T1+C shows a subtle curvilinear enhancing structure (yellow arrow) in the RT frontal white matter representing a DVA , (b) Susceptibility weighted shows a focus of susceptibility artifact (red arrow) , suggestive of an adjacent cavernous malformation

3-Catheter Angiography :-Medusa head seen on venous phase (hallmark)-Dilated medullary veins draining into a large

transcortical vein

2-Vein of Galen Malformation :a) Definitionb) Typesc) Radiographic Findings

a) Definition :-Complex group of vascular anomalies that

consist of a central AVM and resultant varix of the vein of Galen (incorrectly referred to as vein of Galen aneurysm)

b) Types :-Two main types exist with the common feature

of a dilated midline venous structure :1-Vein of Galen AVM2-Vein of Galen varix

1-Vein of Galen AVM :-Primary malformation in development of vein of Galen-AV shunts involving embryologic venous precursors

(median vein of prosencephalon)-Choroidal arteriovenous fistula with no nidus-Absence of normal vein of Galen-Median vein of prosencephalon does not drain normal

brain tissue-Manifests as high-output congestive heart failure

(CHF) in infants and hydrocephalus in older children

Median prosencephalic vein of Markowski shown in an artist’s impression , its afferent arteries are the choroidal arteries and the anterior cerebral artery (ACA)

2-Vein of Galen Varix :-Primary parenchymal AVM drains into vein of

Galen which secondarily enlarges-Thalamic AVM with nidus is usually the primary

AVM-Uncommon to present in neonates-Higher risk of hemorrhage than the vein of

Galen AVM

c) Radiographic Findings :1-Ultrasound2-Catheter Angiography3-CT & MRI4-Chest Radiography

1-Ultrasound :-First choice imaging modality-Sonolucent midline structure superior / posterior

to 3rd ventricle-Color Doppler ultrasound (US ) to exclude

arachnoid/developmental cyst

2-Catheter Angiography :-Used to determine type and therapy-Endovascular embolization : therapy of choice

Lateral view of the RT ICA angiogram, the arterial supply including the left anterior pericallosal artery (arrows), right medial posterior choroidal arteries (small arrowhead), and right lateral posterior choroidal arteries (large arrowhead) are shown

Lateral view of the LT ICA angiogram, multiple feeding arteries from the left medial posterior choroidal arteries (small arrowhead) and left lateral posterior choroidal arteries (large arrowhead) demonstrate shunting at the inferior-caudal portion of the dilated galenic vein (arrow)

(a) Sagittal T1 shows the markedly enlarged median prosencephalic vein of Markowski, characteristic of VGAM (arrow), arterial feeders can be seen along the anterior wall of the vein, (b) the complex arterial maze (arrows) is well seen on this conventional angiogram obtained with injection of the left vertebral artery, coils can be seen along the right side of the varix, occluding several arterial feeders

3-CT & MRI :-Indicated to assess extent of brain damage that

influences therapy

4-Chest Radiography :-High-output CHF, large heart

CT angiography axial image showing enlarged median prosencephalic vein ( large arrow) with multiple arterial feeders ( small arrows)

CT angiography sagittal image showing enlarged median prosencephalic vein (black arrow) continuing in the falcine sinus (red arrow) with enlarged confluence of sinuses

(a & b) Sagittal reconstructions of CT angiograms showing choroidal type , vein of Galen malformation in a neonate , the falcine draining sinuses are massively enlarged because of narrowing of both sigmoid sinuses

CT+C

In utero diagnosis of vein of Galen malformation , MRI performed in the third trimester showing a dilated midline vascular structure in sagittal (a) , axial (b) and coronal (c) planes

T1 T2

T1 T2

T2, the dilated galenic vein, namely the median vein of prosencephalon (thick arrow), located midline in the cistern of velum interpositum, drains into the parietal superior sagittal sinus (thin arrow) via the persistent primitive falcine sinus (arrowhead)

Chest X-Ray AP view showing cardiomegaly with prominent vascular markings

c) Capillary Telangiectasia :1-Definition2-Location3-Radiographic Features

1-Definition :-Nests of dilated capillaries with normal brain

interspersed between dilated capillaries-Commonly coexist with cavernous malformation-A Do NOT Touch lesion

2-Location :-pons > cerebral cortex, spinal cord > other locations

3-Radiographic Features :a) CTb) MRIc) Catheter Angiography

a) CT :-Is often normal

b) MRI :-Foci of increased signal intensity on contrast-enhanced

studies-T2 : hypointense foci if hemorrhage has occurred

c) Catheter Angiography :-Is often normal but may show faint vascular stain

(a) T1+C Patient with midbrain capillary telangiectasia showing brush-like enhancement in the right midbrain , (b) Gradient shows subtle increased susceptibility in the right midbrain

GRE T1 T1+C

d) Moyamoya Disease :1-Definition2-Clinical Picture3-Radiographic Findings

1-Definition :-Uncommon occlusive disease of unknown origin

that classically involves the supraclinoid internal carotid arteries with relative sparing of the posterior fossa in the early stages

-The term moyamoya syndrome is used in cases in which no underlying cause (atherosclerosis, Down syndrome, neurofibromatosis, sickle cell disease or some other condition) can be identified

-There is usually development of extensive tiny basal perforator collateral vessels ( the moyamoya vessels ) which have been described as having a puff of smoke appearance at cerebral angiography and of transdural collateral vessels

2-Clinical Picture :-Differs between pediatric and adult

populations: a) Most children present with transient ischemic

attack or cerebral infarctions b) Approximately one-half of adults present with

intracranial hemorrhage from rupture of the moyamoya collateral vessels

3-Radiographic Findings :a) CT & MRIb) Catheter Angiography

a) CT & MRI :-Imaging include the presence of tiny flow voids,

commonly seen arising from the basal cisterns and extending into the basal ganglia or the thalamus

-There is no true nidus embedded within the brain parenchyma and no dilated vessels

-The diagnosis can be suggested by the presence of bilateral supraclinoid internal carotid artery stenosis at MRA and CTA

b) Catheter Angiography :-Cerebral angiography remains necessary for

preoperative evaluation for the revascularization of moyamoya disease

-There is usually development of extensive tiny basal perforator collateral vessels the moyamoya vessels) which have been described as having a puff of smoke appearance

-The multitude of secondary collateral pathways (basal moyamoya perforator collateral vessels, transdural supply from the middle meningeal arteries to the convexity and through the ophthalmic artery to the ACA branches) can often be evaluated only with digital subtraction angiography due to their small size

MRA

Typical features of moyamoya disease, including severe stenosis of the bilateral ICA (arrows) and basal collateral networks

Sequencing of the right carotid anteroposterior angiograms from initial (A) to early (B), mid (C), and late (D) arterial filling, it shows steno-occlusion of the anterior and middle cerebral arteries, fine vascular networks (arrows) from the lenticulostriate arteries anastomose with medullary arteries, which eventually reconstitute the middle cerebral artery