Intracranial vascular malformations by Dr. Gobardhan Thapa

1. IMAGING IN INTRA CRANIAL
VASCULAR MALFORMATION
Dr. Gobardhan Thapa
Resident, MD Radiodiagnosis
NAMS, Bir hospital

2. Etiology
• Most intra-cranial vascular malformations
(CVMs) are congenital lesions and represent
morphogenetic errors affecting arteries,
capillaries, veins, or a combination of these
elements.
• Mutations in various components of the
vasculogenesis (angiogenetic systems) have
been implicated in the development of various
CVMs.

3. Classification
• CVMs have been traditionally classified by
histopathology into four major types:
1. Arteriovenous malformations (AVMs),
2. Venous angiomas (developmental venous
anomalies),
3. Cavernous malformations.
4. Capillary telangiectasias (sometimes simply
termed “telangiectasia” or “telangiectasis”)

4. Functional classification:
CVMs that display arteriovenous shunting
– Arteriovenous malformation
– Dural venous fistula
– Vein of Galen malformation
CVMs without AV shunting
– Developmental venous anomaly (DVA)
– Sinus pericranii
– Cavernous malformations
– Capillary telangiectasia
• The former are potentially amenable to endovascular intervention;
• the latter are either treated surgically or left alone.

5. CVMs with Arteriovenous Shunting:
Arteriovenous Malformation (AVM)
• tightly packed tangle of thin-
walled vessels with direct
arterial to venous shunting.
• No intervening capillary bed.
• Mostly parenchymal lesions
and are also called “pial
AVMs,” although mixed pial-
dural malformations do
occur.
Fig. Graphic depicts AVM nidus
with intranidal aneurysm ,
feeding artery (“pedicle”)
aneurysm
, and enlarged draining veins .

6. • Mostly solitary (~98%).
• Multiple AVMs are almost always syndromic
(2%) - Common associations:
– hereditary hemorrhagic telangiectasia (HHT, also
known as Rendu-Osler-Weber disease) and
– segmental neurovascular syndromes called
cerebrofacial arteriovenous metameric syndrome
(CAMS).
• E.g. Wyburn-Mason syndrome (AVMs in retina and
brain).

7. • Tiny (“micro” AVMs) to giant lesions
occupying most of a cerebral
hemisphere (usually 2-6 cm).
• Grossly, compact ovoid or pyramidal
lesions.
• Broadest surface at or near the
cortex, and the apex toward the
ventricles.
• The brain surrounding an AVM often
appears abnormal e.g. “perinidal”
capillary bed in some cases.
• Hemorrhagic residue in adjacent
brain are common, as are gliosis and
secondary ischemic changes.
Fig. Autopsy case demonstrates a classic
AVM. The nidus contains no normal
brain. An intranidal aneurysm is present.

8. • Peak age between 20-40 years of age, ~25%
patients with an AVM - symptomatic by age
15.
• No gender predilection.
• Most common presentation: Headache with
parenchymal hemorrhage (50%). Seizure and
focal neurologic deficits are the initial
symptoms in 25% each.

9. • Size
– Small (< 3 cm) = 1
– Medium (3-6 cm) = 2
– Large (> 6 cm) = 3
• Eloquence of Adjacent Brain
– Noneloquent = 0
– Eloquent = 1
• Venous Drainage
– Superficial only = 0
– Deep component = 1
Eloquent areas: sensorimotor cortex, visual cortex, deep nuclei,
internal capsule, thalamus, hypothalamus, brain stem, cerebellar
peduncle
AVMs are graded on a scale from 1-5 based on the sum of “scores”
Spetzler-Martin (SM) scale

11. TREATMENT OPTIONS.
• Embolization,
• surgery,
• stereotactic radiosurgery,
• or a combination of treatments are all.

12. Imaging
Three distinct
components:
• Feeding arteries,
• A central nidus,
and
• Draining veins

13. CT FINDINGS
• “bag of worms” formed by a
tightly packed tangle of vessels
with little or no mass effect on
adjacent brain.
• NECT - numerous well-
delineated, slightly hyperdense
serpentine vessels.
• Calcification common.
• Enhancement of all three AVM
components (feeding arteries,
nidus, draining veins) -typically
intense and uniform on CECT
scans
Fig. (Left) NECT shows serpentine
hyperdensities . (Right) CECT shows
strong uniform enhancement.
Wedge-shaped configuration is
typical for AVM.

14. MR FINDINGS
• High-flow lesions - tightly packed
mass or a “honeycomb” of “flow
voids” on both T1- and T2 scans.
• Brain parenchyma within an AVM is
typically gliotic and hyperintense on
T2WI and FLAIR.
• Contrast enhancement of AVMs is
variable, depending on flow rate and
direction. Draining veins typically
enhance strongly and uniformly .
• Hemorrhagic residue are common -
Foci of “blooming” both within and
around AVMs.
Fig. A. Axial T1WI in a 32-year old man with headache shows a
classic wedge-shaped left parietal AVM with multiple serpentine
“flow voids” . A few linear foci of T1 shortening represent
thrombosed vessels within the nidus. B. T2WI in the same
patient nicely demonstrates the wedge of “flow voids”
Fig. C. FLAIR scan demonstrates minimal
hyperintensity within and around the AVM ,
suggesting small foci of gliotic brain; D. T1 C+
scan shows some linear and serpentine areas of
enhancement that are mostly in draining veins.

15. ANGIOGRAPHY
(CTA, MRA, DSA)
• The feeding arteries - often enlarged and tortuous ; a flow-induced
‘’pedicle” aneurysm’’ (~10-15% of cases).
• Nidus - a tightly packed tangle of abnormal arteries and veins without an
intervening capillary bed.
• ~ 50% - at least one aneurysmally dilated vessel (“intranidal aneurysm”).
• Draining veins typically opacify in the mid- to late-arterial phase (“early
draining” veins). Veins draining AVMs are typically enlarged, tortuous, and
may become so prominent that they form varices and exert local mass
effect on the adjacent cortex.
• Stenosis of one or more “outlet” draining veins may elevate intranidal
pressure and contribute to AVM hemorrhage.

16. Fig. E. Lateral DSA shows enlarged MCA, ACA feeding vessels with a
tangle of smaller vessels in the wedge shaped nidus . Faint opacification
of the superior sagittal sinus represents arteriovenous shunting of
contrast. F. Late arterial phase of the DSA shows the nidus and “early
draining” veins emptying into the SSS . No deep venous drainage was
identified.

17. Fig. Three dimensional angiogram showing the
brain AVM (arrow). The angiogram permits a
more detailed view of the AVM and the blood
vessels that surround it.

18. Cerebral Proliferative Angiopathy
(diffuse nidus type AVM)
• rare entity characterized by diffuse
angiogenesis and progressive hyper vascular
shunting.
• Large lesions that can occupy most of a lobe
or even an entire cerebral hemisphere.
• Unlike classic BAVMs; CPAs - normal brain
parenchyma interspersed between the
proliferative vascular channels and absence
of early venous drainage.

19. • presentation with seizure (45%), severe
headache (40%), or progressive neurologic
deficits. Only 12% present with a hemorrhagic
event.
• Mean age at symptom onset is 22 years. There
is a 2:1 female predominance.

20. Imaging
• CT/MR - large (usually
more than six
centimeters), diffusely
dispersed network of
innumerable dilated
vascular spaces
intermingled with normal
brain parenchyma. Dense
enhancement following
contrast.
Fig. Proliferative type brain AVM in a 27-year-old woman
who presented with a 6-year history of headaches and
seizures. Axial CECT - enhancing vascular lesion in the left
parasagittal frontal lobe, with internal focal
isoattenuating areas representing normal brain
parenchyma interspersed within the nidus.

21. Fig. Proliferative angiopathy in a 26-year-old man with a 6-year history of
progressive left-sided weakness. Axial proton-density–weighted (a) and
gadolinium-enhanced T1-weighted (b) MR images 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.

22. DSA
• Well-circumscribed nidus -
absent. Instead, multiple
small caliber non-dominant
feeding arteries present.
• The draining veins only
moderately enlarged
relative to the striking
extent of the vascular
abnormality.
• Despite their large size,
flow related aneurysms
are not a feature of CPA.
Fig. DSA of selective internal carotid angiogram in a
patient with cerebral proliferative angiopathy shows
innumerable dilated vascular spaces with no dominant
feeding arteries.
Fig. Selective vertebral angiogram in the same patient
shows additional small feeding vessels supplying the lesion.
Despite its size, there are unopacified spaces within the
lesion.

23. Dural arteriovenous fistula (dAVF)
• second major type of
cerebrovascular
malformation - Much
less common than
AVMs
• network of tiny, crack-
like vessels that shunt
blood between
meningeal arteries and
small venules within
the wall of a dural
venous sinus.
Fig. Graphic depicts dAVF with thrombosed
transverse sinus with multiple tiny arteriovenous
in the dural wall . Lesion is mostly supplied by
transosseous feeders from the external carotid
artery.

24. Pathology
• Most common locations in adults - transverse,
sigmoid, and cavernous sinuses.
• The superior sagittal sinus more common in
children.
• Size varies from tiny single vessel shunts to
massive complex lesions with multiple feeders
and arteriovenous shunts in the sinus wall.

25. • 10-15% of all intracranial vascular malformations with
arteriovenous shunting.
• Peak age is 40-60 years, roughly 20 years older than the
peak age for AVMs.
• No gender predilection.
• Uncomplicated dAVFs in the transverse/sigmoid sinus
region - either bruit and/or tinnitus.
• dAVFs in the cavernous sinus - pulsatile proptosis,
chemosis, retroorbital pain, bruit, and ophthalmoplegia.
• “Malignant” dAVFs, lesions with cortical venous drainage -
seizures and progressive dementia in addition to focal
neurologic deficits.

26. Imaging: CT
findings
• Hemorrhage: uncommon in the absence
of cortical venous drainage or dysplastic
venous dilatation.
• An enlarged dural sinus or draining vein
can sometimes seen in NECT. Carotid-
cavernous fistulas - an enlarged superior
ophthalmic vein.
• Dilated transcalvarial channels from
enlarged transosseous feeding arteries
can occasionally be seen on bone CT
images.
• CECT - enlarged feeding arteries and
draining veins. The involved dural venous
sinus is often thrombosed or stenotic.
Fig. A. CTA source image in a patient with right-
sided tinnitus shows no obvious abnormality,
although the right sigmoid sinus looks peculiar.
B. Bone CT in the same patient shows multiple
enlarged transosseous vascular channels in the
squama of the right occipital bone.

27. MR FINDINGS
• Dilated cortical veins without an
identifiable nidus adjacent to
normal-appearing brain may suggest
the presence of a dAVF.
• Mostly, a thrombosed dural venous
sinus containing vascular-appearing
“flow voids”.
• Thrombus is typically isointense with
brain on T1- and T2 scans and
“blooms” on T2* sequences.
Chronically thrombosed sinuses may
enhance.
Fig. C. CE MRA source image shows dural sinus thrombosis ,
multiple enhancing vascular channels characteristic of
posterior fossa dAVF. D. MRA in the same patient shows
innumerable tiny feeding arteries supplying a dAVF at the
transverse-sigmoid sinus junction. The sinus has partially
recanalized , and the distal sigmoid sinus and jugular bulb
are partially opacified.

28. ANGIOGRAPHY
• CTA/CTV; DSA (best imaging
tool with superselective
Catheterization)
• As most dAVFs arise adjacent
to the skull base, multiple
enlarged dural and
transosseous branches
arising from the external
carotid artery are usually
present.
• Dural branches may also
arise from the internal
carotid and vertebral
arteries.
Fig. A. DSA of the external carotid artery in a
patient with tinnitus, dAVF in the occluded
transverse sinus supplied by the middle meningeal
artery , transosseous branches from the ECA.

29. Cognard Classification
• Grade 1: In sinus wall; normal antegrade venous drainage (low risk; benign clinical
course)
• Grade 2A: In sinus; reflux to sinus, not cortical veins
• Grade 2B: Reflux (retrograde drainage) into cortical veins (10-20% hemorrhage)
• Grade 3: Direct cortical venous drainage; no venous ectasia (40% hemorrhage)
• Grade 4: Direct cortical venous drainage + venous ectasia (65% hemorrhage)
• Grade 5: Spinal perimedullary venous drainage
Borden Classification
• Type I: Dural arterial supply with antegrade drainage into venous sinus
• Type Ia: Simple dAVF with single meningeal arterial supply
• Type Ib: Complex dAVF with multiple meningeal arteries
• Type II: Dural supply + ↑ intrasinus pressure → antegrade sinus, retrograde
cortical venous drainage
• Type III: Dural arteries drain into cortical veins

30. Carotid-Cavernous Fistula
• CCFs are divided into two subgroups,
direct and indirect fistulas.
• “Direct” CCFs are typically high-flow
lesions that result from rupture of the
cavernous internal carotid artery (ICA)
directly into the cavernous sinus (CS),
with or without a preexisting ICA
aneurysm.
• “Indirect” CCFs are usually slow-flow,
low-pressure lesions that represent an
arteriovenous fistula between dural
branches of the cavernous ICA and the
cavernous sinus.
Fig. Coronal graphic depicts a carotid-
cavernous fistula (CCF). The right
cavernous sinus is enlarged by numerous
dilated arterial and venous channels.

31. • CCFs usually acquired lesions; traumatic or non-traumatic
in origin.
• Most direct CCFs - traumatic, usually secondary to central
skull base fractures. Either stretch injury to the ICA or direct
puncture from a bony fracture fragment.
• A single-hole laceration/transection of the cavernous ICA
with direct fistulization into the CS is the typical finding.
• Spontaneous (i.e., nontraumatic) rupture of a preexisting
cavernous ICA aneurysm is less common.
• Indirect CCFs - nontraumatic lesions and thought to be
degenerative in origin. In contrast to dAVFs elsewhere,
indirect CCFs rarely occur as sequelae of dural sinus
thrombosis.

32. • Grossly, direct CCF - arterialized
flow causes dilatation of the CS
with venous hypertension and
retrograde flow into the
superior and inferior ophthalmic
veins.
• Indirect CCFs demonstrate
enlarged crack-like vessels
within the CS that resemble
those seen in typical dAVFs
elsewhere.
Fig. Clinical photograph of a patient
with a CCF shows numerous enlarged
scleral vessels.

33. BARROW CLASSIFICATION
OF CAROTID-CAVERNOUS
FISTULAS
Type A: Direct ICA-cavernous
sinus high-flow shunt
Type B: Dural ICA branches-
cavernous sinus shunt
Type C: Dural ECA-cavernous
sinus shunt
Type D: Both ICA/ECA dural
branches shunt to CS

34. Clinical Issues
• Indirect CCF is the second most
common site of intracranial dAVF,
following the transverse/sigmoid sinus
junction.
• Indirect CCFs are most frequent in
women 40-60 years of age.
• As direct CCFs typically occur with
trauma, they are found in both
genders and at all ages.
• Direct high-flow CCFs are much less
common.
• Direct CCFs may present within hours
to days or even weeks following
trauma.
Bruit, pulsatile exophthalmos, orbital edema, decreasing vision, glaucoma,
and headache are typical.
In severe cases, vision loss may be rapid and severe. Cranial neuropathy may
occur but is less common.

35. Imaging
CT FINDINGS
• NECT - mild or striking
proptosis, a prominent CS
with enlarged superior
ophthalmic vein (SOV), and
enlarged extraocular
muscles.
• “Dirty” fat secondary to
edema and venous
engorgement
• Occasionally, subarachnoid
hemorrhage from trauma or
ruptured cortical veins.
• CECT - enlarged SOV and CS;
Fig. CECT scan shows classic findings of
CCF. The right cavernous sinus is enlarged
[BULGING CAVERNOUS SINUS], and the
ipsilateral superior ophthalmic vein is more
than 4 times the size of the left superior
ophthalmic vein.

36. MR FINDINGS
• T1 - prominent “bulging” CS
and SOV as well as “dirty”
orbital fat.
• T2 - multiple “flow voids”
in the CS.
• Strong, uniform
enhancement of the CS and
SOV is typical.
• Enlarged, tortuous
intracranial veins may occur
with high-flow, high-
pressure shunts.
Fig. T2WI shows typical MR
findings of CCF with an enlarged
right cavernous sinus containing
numerous abnormal “flow voids”

37. ANGIOGRAPHY
• Direct CCFs - rapid flow with
very early opacification of
the CS.
• A single-hole fistula is
usually present, typically
between the C4 and C5 ICA
segments.
Fig. Lateral DSA in a case of direct CCF in
a 21-year-old woman with multiple skull
base fractures shows that the ICA
narrows before terminating in a large
venous pouch . High-pressure venous
reflux into the superior and inferior
ophthalmic veins and the sphenoparietal
sinus is present.

38. Pial arterio-venous fistula (pAVF)
• rare vascular malformation; a single
dilated pial artery connecting directly
to an enlarged cortical draining vein.
• No intervening capillary bed or nidus.
• Unlike dural AVFs, 80% of pAVFs are
supratentorial.
• Typically lie on or just within the brain
surface or adjacent to the ventricular
ependyma.
• supplied by branches of the anterior,
middle, or posterior cerebral arteries
and are usually associated with a
venous varix. Fig. Pial AVF with slightly enlarged
ACA branches connecting to a venous
varix , dilated cortical draining vein

39. Fig. Coronal T1 C+ scan shows a pial AVF in the posterior fossa. A
small cerebellar artery connects directly to a venous pouch , which
in turn drains into a subependymal vein near the fourth ventricle.

40. Vein of Galen Aneurysmal Malformation
• most common extra-cardiac
cause of high output cardiac
failure in newborns.
• direct arteriovenous fistula
between deep choroidal
arteries and a persistent
embryonic precursor of the
vein of Galen.
• flow-related aneurysmal
dilatation of this primitive
vein, forming a large midline
venous pouch that lies
behind the third ventricle.
Fig. Graphic illustrates vein of Galen malformation.
Enlarged choroid arteries drain directly into dilated
median prosencephalic vein (MPV) , falcine sinus .
Torcular herophili (venous sinus confluence) is
massively enlarged.

41. • Normal fetal development, arterial supply to
the choroid plexus drains via a single transient
midline vein, the median prosencephalic vein
(MPV) of Markowski.
• Normally, the developing internal cerebral
veins annex drainage of the fetal choroid
plexus, and the MPV regresses.
• In a VGAM, a high-flow fistula prevents
formation of the definitive vein of Galen.

42. Pathology
• Grossly - enlarged arteries drain
directly into a dilated MPV.
• “Aneurysmal” dilatation of the
persistent MPV forms a large venous
pouch behind the third ventricle that
often drains into a markedly enlarged
superior sagittal sinus via an
embryonic falcine sinus.
• The ventricles are often markedly
dilated.
• The brain is frequently atrophic.
• Ischemic changes are common.

43. • < 1% of all CVM but ~30% of symptomatic vascular
malformations in children.
• Neonatal VGAMs are more common than those presenting
in infancy or childhood. Adult presentation is rare.
• (M:F = 2:1).
• Neonates, high-output congestive heart failure and a loud
cranial bruit are typical. Older infants may present with
macrocrania and hydrocephalus, with or without heart
failure.
• VGAMs in older children are often associated with
developmental delay and seizures.
• VGAMs in young adults typically present with headache
with or without hemorrhage and hydrocephalus.

44. Imaging: CT findings
• NECT - enlarged, well
delineated, mildly hyperdense
mass at the tentorial apex,
usually compressing the third
ventricle and causing severe
obstructive hydrocephalus.
• Variable encephalomalacia,
hemorrhage, and/or dystrophic
calcification in the brain
parenchyma.
• CECT - strong uniform
enhancement.
Fig. CECT scan in a newborn
demonstrates a massive VGAM
draining into an enlarged falcine sinus,
causing obstructive hydrocephalus.

45. MR FINDINGS
• Enlarged arterial
feeders are usually seen
as serpentine “flow
voids” adjacent to the
lesion.
• Thrombus of varying
ages may be present
lining the VGAM.
Fig. Sagittal T2WI shows prominent arteries
supplying an enlarged median prosencephalic
vein. Note enlarged falcine sinus .

46. ANGIOGRAPHY
• Two forms of VGAM are
recognized based on their
specific angioarchitecture.
• In more than 50% of all
VGAMs, the straight sinus is
hypoplastic or absent and
venous drainage is into a
persistent embryonic “falcine
sinus.”
• The falcine sinus is easily
identified as it angles
posterosuperiorly toward the
superior sagittal sinus.
Fig. DSA in the same patient shows that
the VGAM is supplied by multiple direct
arterial fistulas

47. ULTRASOUND
diagnosed antenatally
• hypoechoic to mildly
echogenic midline mass
behind the third ventricle is
typical.
• Color Doppler shows
bidirectional turbulent flow
within the VGAM
Fig. Neonatal transcranial US shows a large
VGAM posterior to the 3rd ventricle. Prominent
vessels with arterial flow supply the lesion.

48. CVMs without Arteriovenous Shunting
Developmental Venous Anomaly
• With the advent of contrast-enhanced MR, developmental
venous anomalies have become the most frequently diagnosed
intracranial vascular malformation (60% of CVM of brain).
• Once thought to be rare lesions with substantial risk of
hemorrhage, the vast majority of venous “angiomas” are now
recognized as asymptomatic and incidental imaging findings.
• Neurologic complications are rare.

49. • an umbrella-shaped congenital cerebral vascular malformation
composed of angiogenically mature venous elements.
• Dilated, thin-walled venous channels lie within (and are
separated by) normal brain parenchyma.
Fig. Autopsy case shows left frontal
DVA as dilated medullary veins
interspersed with normal brain.
Fig. Graphic depicts DVA with
enlarged medullary veins
draining into a single transmantle
collector vein .

50. • In the deep white matter (WM), adjacent to the frontal
horn of the lateral ventricle.
• The second most common location is next to the fourth
ventricle.
• Size varies from tiny, almost imperceptible lesions to giant
DVAs that can involve most of the hemispheric WM.
• A cluster of variably sized enlarged medullary (WM) veins
embedded within brain parenchyma

51. • found in patients of all ages without gender
predilection.
• Mostly incidentally at autopsy or on imaging
studies.
• 98% of all DVAs are asymptomatic.
• Two percent - hemorrhage or infarct, probably
caused by stenosis or spontaneous thrombosis
of the outlet collector vein.

52. • Most DVAs solitary; unless associated with a
vascular neurocutaneous syndrome such as
blue rubber bleb nevus syndrome.
• DVAs may coexist with a sinus pericranii. Sinus
pericranii is typically the cutaneous sign of an
underlying venous anomaly. DVAs are also
associated with periorbital
lymphatic/lymphaticovenous malformations.

53. • No treatment is required or recommended
for solitary DVAs (they are “leave me alone!”
lesions).
• If a DVA is histologically mixed, treatment is
determined by the coexisting lesion.
Preoperative identification of such mixed
malformations is important as ligating the
collector vein or removing its tributaries may
result in venous infarction.

54. Imaging
• NECT - usually normal
unless the DVA is very
large and a prominent
draining vein is present.
• CECT - numerous linear
and/or punctate
enhancing foci that
converge on a well-
delineated tubular
collector vein. Fig. CECT, CTA depict classic DVA in
the left cerebellar hemisphere

55. MR FINDINGS
• Small DVA - may be undetectable unless
contrast-enhanced scans are obtained.
• T1 C+ sequences - a stellate collection of
linear enhancing structures converging on
the transparenchymal or subependymal
collector vein.
• The collector vein may show variable
high-velocity signal loss. Because flow in
the venous radicles of a DVA is typically
slow, blood deoxygenates and T2* scans
(GRE, SWI) show striking linear
hypointensities.
• If a DVA is mixed with a cavernous
malformation, blood products in various
stages of degradation may be present and
“bloom” on T2* sequences.
Fig. T1 C+ scan shows a classic DVA
with enlarged WM veins and a
collector vein draining into the
anterior aspect of the superior
sagittal sinus.

56. ANGIOGRAPHY
• The arterial phase is normal.
• The venous phase shows
the typical hair-like
collection (“Medusa
head/inverted umbrella”)
of dilated medullary veins
within the white matter.
Fig. 3D SSD demonstrates a classic DVA
with enlarged medullary veins draining
into the collector vein. The appearance
resembles a “Medusa head,” “upside-
down willow tree” or “umbrella.”

57. Sinus Pericranii
• large transcalvarial
communication between the
intra- and extracranial
venous drainage systems.
• A bluish sac beneath or just
above the periosteum of the
calvaria is typical. The
dilated, blood-filled sac
connects through an
enlarged emissary vein with
the intracranial circulation.
Fig. Coronal graphic depicts a
classic sinus pericranii (SP) with an
expanded venous pouch under the
scalp connecting to the intracranial
venous system through a
transcalvarial channel . Some SPs
are associated with a
developmental venous anomaly .

58. • The frontal lobe is the most common site, followed by
the parietal and occipital lobes.
• SPs in the middle and posterior cranial fossae are rare.
• SP may be associated with single or multiple intracranial
DVAs.

59. • Rare lesions (<10% of patients who present for treatment
of craniofacial vascular malformations and 4% of patients
with palpable scalp/cranial vault lesions).
• Mostly in children or young adults; No gender predilection.
• A nontender, non-pulsatile somewhat bluish compressible
scalp mass that increases with Valsalva maneuver and
reduces in the upright position is typical.
• A history of “forgotten trauma” is not uncommon.
• Mostly asymptomatic, other than their cosmetic effect.
• SP with multiple DVAs is associated with blue rubber bleb
nevus syndrome.

60. • Most SPs behave benignly and remain stable
in size.
• Surgical removal of the extracranial
component with cranioplasty is occasionally
performed for cosmetic purposes.
• Surgery without adequate imaging may result
in potentially lethal complications including
hemorrhage, venous infarction (if the SP is
associated with a DVA), and air embolism.

61. Imaging
• A vascular or subperiosteal scalp
mass overlies a well-defined bone
defect. The mass communicates
directly with the intracranial
venous system through the bony
defect.
• CT - iso- or hyperdense on NECT
and shows strong uniform
enhancement after contrast
administration.
• Occasionally an SP may contain
calcifications (phleboliths) or
thrombi. Fig. Sagittal CTV shows a small sinus
pericranii connecting to the superior
sagittal sinus through an adjacent skull
defect.

62. MR FINDINGS
• Most SPs are isointense on
T1WI and hyperintense to
brain on T2WI.
• “Puddling” of contrast
within the SP on T1 C+ is
typical unless the lesion is
unusually large and flow is
rapid.
• MRV is helpful in
delineating both the intra-
and extracranial
components.
Fig. Coronal contrast enhanced MR
scan shows a classic sinus pericranii
that connects to the superior sagittal
sinus via a small transcalvarial venous
channel.

63. ANGIOGRAPHY
• The arterial and capillary phases are
normal. Mostly seen only on the very late
venous phase.
• well-defined rounded pools of contrast
that slowly accumulate within and
adjacent to the skull defect containing the
transcalvarial vein.
• Flow is variable and often bidirectional.
ULTRASOUND
• Color Doppler may delineate the
extracranial component and define flow
direction.
• US does not define the intracranial
component of an SP.
Fig. Late venous phase DSA
shows angiographic findings of
sinus pericranii with enlarged
venous pouches connecting
directly to the superior sagittal
sinus through a transcalvarial
channel.

64. Cerebral Cavernous Malformation
• Intracranial vascular
malformation characterized by
repeated “intralesional”
hemorrhages into thin-walled,
angiogenically immature, blood-
filled locules called “caverns.”
• Discrete, well-marginated lesions
that do not contain normal brain
parenchyma.
• Most are surrounded by a
complete hemosiderin rim.
Fig. Subacute , classic “popcorn ball”
appearances of CCMs.
Microhemorrhages are seen as
multifocal “blooming black dots”

65. • relatively common cause of spontaneous
nontraumatic intracranial hemorrhage in
young and middle-aged adults, although they
can occur at any age.
• Occur throughout CNS
• Solitary (2/3), multiple (1/3, familial)

66. • Third most common CVM
• At any age; peak = 40-60 years -- like DAVF
• Course variable, unpredictable
• Repeated intralesional hemorrhages typical
Hemorrhage risk = 0.25-0.75% per lesion per
year
• Patients with familial CCM develop de novo
lesions.

67. ZABRAMSKI CLASSIFICATION OF Cerebral CMs
Type 1: Subacute hemorrhage
Hyperintense on T1, hyper-/hypointense on T2
Type 2: Different age hemorrhages
Classic = “popcorn ball”
Mixed signal with hyper/hypo on both T1 and T2
Blood-filled locules with fluid-fluid levels
Type 3: Chronic hemorrhage
Type 4: Punctate microhemorrhages
“Blooming black dots” on T2* (GRE, SWI)

68. Imaging
• NECT: Hyperdense ± scattered
Ca++
• MR: Appearance varies
• “Popcorn ball” with fluid-fluid
levels, hemosiderin rim
• Multifocal “blooming black
dots”
• DSA usually negative
Fig. T2WI shows classic “popcorn
ball” appearance with locules of
blood in different stages of evolution
surrounded by hemosiderin rim

69. Capillary Telangiectasia
• collection of enlarged,
thin-walled vessels
resembling
capillaries.
• The vessels are
surrounded and
separated by normal
brain parenchyma. Fig. Graphic depicts pontine capillary
telangiectasia with tiny dilated capillaries
interspersed with normal brain.

70. • Cluster of thin-walled,
dilated capillaries
• Normal brain
interspersed between
vascular channels.
• Can be found
throughout CNS; Pons,
cerebellum, spinal
cord most common
sites.
Fig. Autopsy specimen shows a large
pontine capillary telangiectasia . Note the
transverse pontine fibers passing through
the lesion.

71. • 10-20% of all cerebrovascular malformations
• All ages; peak = 30-40 years
• Rarely symptomatic
• Most discovered incidentally at imaging

72. Imaging
• NECT, CECT usually normal
• MR - T1/T2 usually normal
• T2* key sequence (dark gray hypointensity)
• Brush-like enhancement on T1 C+

73. Fig. Series of images demonstrates classic findings of pontine capillary telangiectasia. A. Axial T1WI
is normal. B. Axial T2WI in the same patient likewise shows no abnormality.
C. FLAIR scan shows faint patchy hyperintensity in the pons. D. T2* GRE scan
shows susceptibility effect with grayish hypointensity in the mid pons.

74. Fig. E. T1 C+ scan shows the brush-like faint enhancement that is
characteristic of capillary telangiectasia. F. DTI fiber tracking is normal.
The transverse pontine fibers cross undisturbed through the lesion.

75. summary
TYPE ETIOLOG
Y
PATHOLO
GY
NUMB
ER
LOCATION PREVALE
NCE
AGE HHG RISK IMAGIN
G CLUES
AVM Congenit
al
Nidus+ar
terial
feeders,
draining
veins; no
capillary
bed
Solitar
y <2%
multipl
e)
Parenchym
a (85%
supratento
rial, 15%
posterior
fossa)
0.04-
0.5%
populati
on; 85-
90% of
CVM
with AV
shunting
Peak =
20-40
yrs
Very high;
2-4% per
yr
cumulative
Bag of
worms,
flow
voids on
MR

76. Dural
AV
Fistula
(dAVF)
Acquired
(trauma;
Dural
sinus
thrombo
sis)
Network
of
multiple
AV
microfist
ula
Solitar
y
Skull base;
Dural sinus
wall
10- 15%
of
CVMs
with
AV
shunting
Peak =
40-
60
years
Varies
With
venous
Draining
(increased
if
Cortical
veins
involved)
Enlarged
Meninge
al
Arteries
with
network
of
Tiny
vessels
in wall of
thrombo
sed
Dural
venous
sinus

77. Vein of
Galen
malformat
ion
(VGAM)
Congenital
(fetal
arterial
Fistula to
Primitive
precursor
of vein of
Galen)
Large
venous
pouch
Solitary Behind
Third
ventricle
< 1% of
CVMs
with AV
shunting
Newborn
> >infant,
Older
Child
Low (but
hydroceph
alus brain
damage
common)
Large
midline
venous
varix in
neonate
With high
output
congestive
Heart
Failure

78. Develo
pmental
Venous
anomaly
(DVA)
Congenit
al
(arrested
Fetal
medullar
y
Vein
develop
ment)
Dilated
WM
veins;
Normal
brain in
between
Solitary
(unless
BRBNS)
Deep
WM,
Usually
near
ventricle
Most
com mon
CVM
(60% of
all),
between
2-9% of
the
populati
on
Any
Age
Extremel
y
Low
unless
mixed
with
Caverno
us
malfora
mtion
“Medusa
Head” of
dilated
WM
veins
Convergi
ng on
enlarged
Collector
Vein

79. Sinus
pericranii
(SP)
Congenit
al
Bluish
blood
filled
subcutan
eous
scalp
Mass
Solitary Scalp Rare Any age
(usually
child
hood)
Extremel
y
Low
unless
Direct
trauma
Vascular
Scalp
mass
connecti
ng
through
skull
defect to
intracran
ial
Venous
circulatio
n

80. Cavernous
Malformat
ion
(CM)
Congenital Collection
Of blood
filled
“cave rns”
with no
normal
Brain;
complete
Hemosider
in Rim
2/3 solit
ary (spor
adic) ; 1/3
Multiple
(familial)
Throughou
t
Brain
Any age
(peak =
40-
60 years;
younger in
Familial
CCM
syndrome)
High (0.25-
0.75% per
Year; 1%
per lesion
Per year in
familial)
Varies;
most
common is
solitary
“popcorn
Ball”
(locules
with blood
fluid
levels,
Hemos
iderin
rim);
multifocal
“black
dots”
In familial

81. Capilla
ry
telangi
ectasia
(CT)
Conge
nital
Dilated
capillar
ies;
normal
Brain
in
betwe
en
Solitar
y >
> >
multIpl
e
Anywh
ere
But
pons;
medull
a
Most
comm
on
15-20%
of all
CVMs
Any
age
(peak =
30-40
years)
Extrem
ely low
unless
mixed
with
cavern
ous
malfor
mation
Faint
Brush-
like
enhanc
ement,
becom
es
Hypoin
tense
on T2*

82. References
• Osborn's Brain Imaging; Anne G Osborn.
• Radiologic Assessment of Brain Arteriovenous Malformations:
What Clinicians Need to Know; Geibprasert et al,
RadioGraphics 2010; 30:483–501

83. Thank you !!