Moya Moya on MRI and MRA - PowerPoint Presentation

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Moya Moya on MRI and MRAeEdE#: eEdE-183Control #: 2500

Steven Sogge, MDKrish Thamburaj, MD

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Financial DisclosuresWe do not have any financial disclosures.

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ObjectivesReview the classification and pathophysiology of Moya M

oyaReview the various neuroimaging features of Moya Moya disease on MRI and MRA

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DefinitionProgressive

stenosis of the terminal internal carotid bifurcation including terminal ICA and the proximal segments of ACA and MCA in association with development of dilated perforating arteries that function as collateral pathways.

The Japanese term ‘Moya

Moya

’ is derived from the

resemblance of the

basal collateral

s

to

puff of smoke on cerebral angiography.Guidelines published by the Research Committee on Spontaneous Occlusion of the Circle of Willis (Moyamoya Disease) in 1997 defined the disease as:Moya Moya Disease: Bilateral lesions with no known etiologyProbable Moya Moya: Unilateral lesionMoya Moya syndrome: Bilateral lesions occurring in the background of an underlying lesion

Well known causes of Moya Moya syndromeAtherosclerosis (Probably the most common secondary cause)Sickle cell diseaseDown’s syndromeNeurofibromatosisAutoimmune diseaseMeningitisHead traumaIrradiation to the head

Puff of smoke

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EpidemiologyObserved throughout the world. High incidence in East Asia

. In Japan, the annual prevalence and incidence have been estimated at 3·16 and 0·35 per 100000, respectively.Incidence from western parts of USA 0.086/100,000. Incidence-rate ratios reported in Asian Americans 4.6, B

lacks 2.2, and Hispanics 0.5, as compared with W

hites.F: M = 1.8

Age: Bimodal distribution, primary peak at age 5 with smaller peak at age 40.

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PathophysiologyNot completely understood

Stenosis starts at distal ICA. May start in proximal MCA or ACA before progressing to terminal ICA.Pathology of affected vessel demonstrates smooth muscle proliferation and intraluminal thrombi. Fragmented undulated internal elastic lamina and thin media are evident.

Caspase-3-dependent apoptosis might be associated with these histopathological changes.

Moya Moya vessels also demonstrate similar changes in vessel wall; fragility of vessel wall may result in

microaneurysm

formation. These histopathological changes might be closely associated with the onset of ischemic and hemorrhagic stroke.

(Hematoxylin & eosin) of right terminal ICA shows

hyperproliferation

(black

arrow) of the vessel-wall components and abundant intraluminal thrombi (blue arrow), leading to narrowing and occlusion of the lumen. Scott RM et al., NEJM 2009;360:1226

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Clinical presentationTrasient

ischemic attacks (TIA) and ischemic infarcts typically in younger children. Areas affected tends to be in the territory of the ICA, particularly in the frontal lobe. Repeated insults can

lead to impairment of higher order functions later in life.

Hyperventilation will induce ischemic attacks secondary to decreased PaCO

2

which leads to arterial vasoconstriction.

Intracranial hemorrhage occurs more commonly in older individuals

, those typically occurring around the second peak of incidence. There are two causes of bleed; the first is ruptured of dilated fragile

moya

moya vessels or rupture of saccular aneurysms that occur in the setting of the disease.HeadacheEpilepsyInvoluntary movements

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Diagnostic criteria and classificationHistorically, cerebral angiography is the gold standard

.Cerebral angiography is less than ideal in the primary population affected by Moya Moya due to ionizing radiation exposure.Per guidelines from the Research Committee on Spontaneous Occlusion of the Circle of Willis (Moya Moya Disease), cerebral angiography is not mandatory if MRI and MRA demonstrate:

Stenosis or occlusion at the end of the ICA or at the proximal part of the ACAs and MCAs on MRA, and an

Abnormal vascular network seen in the basal ganglia with MRA.

The new criteria of the Research Committee for Diagnosis of Moyamoya Disease recommend MRA with a 1·5T machine, and MRA scans with 0·5T or 1·0T machines are not recommended

Stenosis or occlusion of the terminal part of the ICA (the C1–C2 portion) and the proximal part of the ACAs and MCAs bilaterally.

Stenosis or occlusion of the proximal part of the posterior cerebral artery also affects about 25% of patients with Moya Moya disease.

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Angiographic Classification of Moya Moya (according to Suzuki and Takaku)

StageCarotid terminus (CT)

Moya Moya collaterals

I

Narrowed

None

II

Narrowed CT and dilated ACA & MCA

Initiation

III

Increasing stenosis of CT and narrowed ACA & MCAIntensificationIV

Occlusion in ICA and tenuous ACA & MCAMinimizationVOcclusion of ICA, ACA and MCAReductionVIVanished ICA with ECA supply to brainDisappearance

DSA demonstrates Stage II Moya Moya in bilateral carotid terminus with unaffected posterior circulation. Note the severe stenosis in terminal ICA, carotid bifurcation and bilateral A1 and M1 segments. Posterior circulation is less involved in

up to 25% of cases.

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Parenchymal changesInfarcts:

Ischemic infarcts occur in deep gray matter, periventricular white matter, cortical areas particularly in frontal lobes and watershed areas.

Acute infarcts are shown best on DWISubacute infarct demonstrate enhancement

Chronic infarct demonstrated by

encephalomal

a

cia

and gliosis

Pathophysiology of ischemia

In children, hyperventilation during crying may result in vasoconstriction and ischemic events. Exertion of induction of anesthesia may also precipitate ischemic events.

Ultimately the brain undergoes atrophic changes.Moya Moya patient with enhancing subacute ischemic infarct in the corpus callosumIschemic stroke presentation

Moya Moya disease with acute infarct in the right temporal lobe (arrow).

FLAIR

DWI

ADC

MRA

FLAIR

Postgad T1

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Parenchymal changes

Serial MRIs show progression of infarcts, initially presenting as unilateral disease

on left

and progressing to bilateral disease. Again note the vulnerability of frontal lobes.

FLAIR

FLAIR

T1

T1

FLAIR

Deep gray matter infarcts are well known in Moya Moya. Note the chronic infarcts in left basal ganglia (arrow)

Periventricular white matter (PVWM) is another area prone to develop infarcts in Moya Moya. Note the chronic infarcts in bilateral PVWM (arrows)

FLAIR

T1

DWI

Superficial watershed infarcts acute and chronic stages on DWI, T1 and FLAIR sequence along the right centrum

semiovale

(arrows)

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Parenchymal changes

Posterior circulation infarct

FLAIR

MRA

Posterior circulation involvement is less common in Moya Moya. It may be seen in

up to

25% of cases. Note the chronic infarcts in bilateral posterior cerebral artery territory on FLAIR (arrows). Also, note on MRA, the lack of flow signals in bilateral posterior cerebral arteries (arrows).

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Intracranial hemorrhage

Intracerebral hemorrhage: Typically occur in basal ganglia. Intraventricular hemorrhage:

Isolated IVH is well known to occur in Moya Moya

, probably due to rupture of fragile hypertrophied choroid vessels.

Subarachnoid hemorrhage:

Uncommon; May result in aneurysmal pattern from ruptured aneurysm developing in response to hemodynamic factors. Maya Moya may result in isolated convexity

sulcal

hemorrhage.

Cerebral

microbleeds

: Some studies report higher incidence of cerebral microbeleeds in Moya Moya. They tend to be located near the periventricular white matter.Isolated intraventricular hemorrhage. Demonstrates hyperintense T1 signals, susceptibility on T2* GRE from intracellular methemoglobin (arrows). Occlusion of bilateral carotid terminus evident on MRA (arrows).Hemorrhagic stroke presentation

More common in adultsPathophysiology: Fragile vessel wall and microaneurysms probably predispose pattients to intracerebral hemorrhage and intraventricular hemorrhage. Hemorrhage in the basal ganglia is well known to occur in Moya Moya. Hemodynamic factors may occasionally result in development of aneurysms at the circle of Willis and episodes of subarachnoid hemorrhage.

T1

T2*GREMRA

Cerebral

microbleed

on SWI in left periventricular white matter (arrows).

SWI

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Ivy sign

Seen on FLAIR sequence. The sulci appear hyp

erintense.

Can be unilateral or bilateral.

Ivy sign is thought to indicate leptomeningeal

collaterals.

Slow

flow in

cortical

vessels also cause sulcal hyperintensity.Differential for sulcal hyperintensity on FLAIR:O2 inhalationAcute subarachnoid hemorrhageMeningitis of all causesCSF flow artefacts

Sulcal hyperintensity (Ivy sign) evident on FLAIR especially on the left side (arrows)

FLAIR

Postgad T1

FLAIR

Postgad T1

FLAIR

Bilateral Ivy sign evident on FLAIR. Enhancing vessels are seen in postcontrast T1

corresponding

to the Ivy sign findings (arrows)

Ivy sign on FLAIR from slow flow in a vessel right posterior temporal region (arrow). Enhancing vessels evident on postcontrast T1 (arrows). This was the only finding in a child presenting with an episode of syncope which led to the diagnosis of Moya Moya

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Collaterals on MRI

Collateral pathways: Based on catheter angiography, classified as

Basal

moyamoya –

From l

enticulo-striate

artery and the thalamo-perforating

artery.

Choroidal &

Pericallosal Ethmoidal moyamoya – From anterior and posterior ethmoidal arteriesVault moyamoya - from dural arteries to pial arteries - it is commonly observed in patients with advanced disease.Effective bypass surgery can result in

disappearance or regression of moyamoya vessels, as they are no longer required to function as collateral pathways.T2

Basal collateral seen as tiny multiple

flow voids on T2 against the bright CSF (arrow). Note the diminished caliber of MCAs

T1

Collaterals seen as flow voids on T1 in bilateral basal ganglia

and thalamus

(arrows)

Basal collateral seen appear as flow voids as well as prominence of perivascular space on Proton density weighted image (arrow). Note the distinct enhancing perforators on postgad T1 (arrows).

PD

Postcontrast T1

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SWI in Moya Moya

Prominent cortical veins from increased deoxyhemoglobin in right MCA and bilateral ACA territory (arrows). MRA shows patency of LMCA (arrow). Right supraclinoid ICA, RMCA and bilateral ACAs are affected.

SWI can

demonstrate:

All forms of hemorrhagic stroke at greater sensitivity than T2*GRE

Depending on the territory involved, ischemia leads increased oxygen extraction and higher concentration of deoxyhemoglobin in the cortical and perimedullary veins. These veins demonstrate more susceptibility signals on SWI in the affected side.

mIP image of SWI

Brush sign seen in Moya Moya: Prominence of perimedullary

veins evident on the left side (arrows). Also, note the prominence of cortical veins in the left MCA territory.

mIP image of SWI

MRA

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MRA in Moya Moya

Technique: Time of flight is the most commonly used technique. Lack of ionizing radiation and lack of IV contrast are major advantages.

TOF

MRA may overestimate

stenosis as

occlusion

.

MRA can also can be used to identify Moya

Moya

collaterals.MRA scores correlated well with the six-stage classification on cerebral angiography, with a high sensitivity and specificity.Can be used to monitor the disease progression as well as post surgical changes.In accordance with the guidelines of the Research Committee on Spontaneous Occlusion of the Circle of Willis (Moya Moya Disease), cerebral angiography is not mandatory if MRI and MRA show all of the following findings: Stenosis or occlusion at the end of the ICA or at the proximal part of the ACAs and MCAs on MRA, and an

Abnormal vascular network seen in the basal ganglia with MRA. The new criteria of the Research Committee for Diagnosis of Moya Moya Disease recommend MRA with a 1.5T machine, and MRA scans with 0.5T or 1.

0T machines are not recommended.

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Stage 3/4 MRA

MRA demonstrates severe stenosis of bilateral carotid terminus (yellow arrows); Note the basal collaterals near the bilateral carotid bifurcation (red arrow). The posterior circulation is also involved (blue arrow).

DSA demonstrates findings similar to MRA. Suzuki stage 3 to 4 bilaterally with prominent collaterals. Note the involvement of bilateral posterior cerebral arteries on vertebral DSA (yellow arrows).

MRA

Selective RICA DSA

MRA

Selective LICA DSA

VA DSA

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Stage 4/5 MRA

MRA

MRA demonstrates severe stenosis of right carotid terminus (yellow arrow); Left carotid terminus is occluded (red arrow). Note the intact posterior circulation (blue arrow).

MRA

DSA demonstrates findings similar to MRA. Suzuki stage approximately corresponds to 4 on the right side and 5 on the left side

Selective RICA DSA

Selective LICA DSA

VA DSA

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Collaterals on MRA

Note the tiny flow signals from collateral in the right sylvian fissure and right basal ganglia (arrows). Note the distinct enhancing perforators on postgad T1 (arrows). Note the stenosis/occlusion in right carotid terminus in MIP image (arrow)

Raw data TOF MRA

MIP image of TOF MRA

Collateral evident in bilateral medial thalamus as well as in the quadrigeminal cistern (arrows).

Raw data TOF MRA

MIP image of TOF MRA

Flow signals from in collateral from posterior cerebral arteries (arrows).

Raw data TOF MRA

Enlarged left anterior choroidal artery (arrows).

MIP image of TOF MRA

MRA can reliably demonstrate various types of collaterals in Moya Moya

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Treatment optionsGoal of treatment is to prevent future ischemic strokes.

Revascularization options: Direct: Involves anastomosis of a branch of the internal carotid artery

either MCA or ACA with

a branch of the external carotid artery to bypass the ICA stenosis.Indirect:

Vascularized tissue supplied by external carotid artery is placed contact with the brain to promote ingrowth of blood vessels.

Types of indirect surgery

Encephalogaleo

synangiosis

Encephaloduroarteriosynangiosis (STA-dura)

Encephalomyoduroarteriosynangiosis

(Temporal muscle-dura)Multiple burr hole surgeryIn this surgery the superficial temporal artery (STA), which is a branch of the external carotid artery, is anastomosed to the cortical conducting branches of the middle cerebral artery or cortical conducting branches of ICA Encephaloduroarteriosynangiosis

From: http://www.dcmsonline.org/jax-medicine/1998journals/november98/bypass.htmFrom: https://neurosurgerycns.files.wordpress.com/2013/07/screen-shot-2013-07-16-at-10-44-29-am.jpg

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MRA and post surgical changesEncephaloduroarteriosynangiosis

(EDAS): - Enlargement of the superficial temporal artery

(STA)

and middle meningeal artery (MMA)

can be

observed

;

A

pproximately

3 months later, well developed collaterals can be seen on MRA.EDAS has a high success rate in pediatric cases. In adults, 40-50% of cases may not develop adequate collaterals.STA-MCA bypass: Patency can be assessed on MRA. Aneurysm may develop rarely at the site of anastomosis. MRA

can help identify the complications. Post treatment changes: • Moya Moya vessels start regressing 1 month after combined bypass surgery. STA and MMA increase their caliber in 3 months after surgery. Stenotic change in the carotid terminations quickly progresses after surgery. There is a reciprocal relation between neovascularization and the regression of moyamoya vessels.

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Right carotid DSA demonstrates right

encephaloduroarteriosynangiosis

. Note the anastomotic site at the level of the dura (arrow) in the frontal view. In the lateral view, hypertrophied parietal branch of STA is seen (yellow arrow). Collaterals opacifying the cortical branch of right MCA (red arrow

)

are observed

.

DSA frontal view

DSA lateral view

Bilateral

encephaloduroarteriosynangiosis.

Collaterals at the site of anastomosis demonstrate

prominent flow voids on the raw data image (arrow). Note the hypertrophied parietal branch of STA entering the calvarium (yellow arrow).

Raw data TOF MRA

MIP image MRA

MIP image MRA

MRA appearance of Encephaloduroarteriosynangiosis

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Perioperative ischemia

Perioperative period can pose risk of ischemia and infarct. Patient developed bilateral frontal infarct following left

encephaloduroarteriosynangiosis.

MRI permits the accurate assessment of parenchymal changes associated with surgery.

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1523366

Dynamic contrast enhanced MR perfusion. CBF

demonstrates decrease in BF RMCA territory

particularly

in the frontal lobe (arrow)

.

CBV shows increased BV

in right MCA and bilateral

AC

A, particularly on the right side

. MTT shows delayed transit RMCA and bilateral ACA. (arrows)MRA

DSANote the excellent correlation between DSA and MRA. Severe stenosis is evident in the right carotid terminus with nonvisualization of RA1 from occlusion. Left is also occluded with failure to visualize the ACA branches on bilateral carotid injections. Note the fetal origin of left PCA. The posterior circulation is intact with left P1 hypoplasia from developmental variation.

MR perfusion in Moya Moya

Several techniques permit assessment of cerebral perfusion including MRI, CT, SPECT and PET

.

MR perfusion can be assessed with

post-contrast

dynamic perfusion and arterial spin labelling technique. Diamox challenge can help identify tissue at risk and guide treatment decisions. MR perfusion permits assessment of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak (TTP) maps.

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ConclusionsMoya Moya disease is an uncommon condition

.The disease can present with ischemic or hemorrhagic stroke, with ischemic strokes more common in the pediatric population.

It

is characterized by development of progressive stenosis carotid terminus with development of collaterals.

DSA is considered

the gold

standard to diagnose. MRI is the noninvasive imaging technique of choice. MRI and MRA can reliably demonstrate several neuroimaging features, satisfying the diagnostic criteria for Moya Moya disease.

MRI

and MRA can be used to monitor the progress of the disease and guide treatment. MR perfusion may help identify cerebral parenchyma at risk.

Post surgical changes and associated improvement and complications can be recognized with MRI and MRA.

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ReferencesScott RM,

and Smith ER. Moyamoya Disease and Moyamoya Syndrome. N Engl J Med 2009;360:1226-37.Kuroda

S(1), Houkin K.

Moyamoya disease: current concepts and future perspectives. Lancet Neurol. 2008 Nov;7(11):1056-66.

doi

: 10.1016/S1474-4422(08)70240-0

.

Suzuki

J,

Takaku

A. Cerebrovascular "moyamoya" disease. Disease showing abnormal net-like vessels in base of brain. Arch. Neurol. 1969;20 (3): 288-99.Mugikura S, Takahashi S, Higano S et-al. The relationship between cerebral infarction and angiographic characteristics in childhood moyamoya disease. AJNR Am J Neuroradiol. 1999;20 (2): 336-43.Yoon HK, Shin HJ, Chang YW. "Ivy sign" in childhood moyamoya disease: depiction on FLAIR and contrast-enhanced T1-weighted MR images. Radiology. 2002;223 (2): 384-9.Bruno A, Adams HP, Biller J et-al. Cerebral infarction due to moyamoya disease in young adults. Stroke. 1988;19 (7): 826-33.Horie N, Morikawa M, Nozaki A et-al. "Brush Sign" on susceptibility-weighted MR imaging indicates the severity of moyamoya disease. AJNR Am J Neuroradiol. 2011;32 (9): 1697-702.Ryoo S, Cha J, Kim SJ, et al. High-Resolution Magnetic Resonance Wall Imaging Findings of Moyamya disease. Stroke 2014; 45: 2457-2460.

Lin R, Xie Z, Zhang J, Xu H, Su H, Tan X, et al. Clinical and immunopathological features of moyamoya disease. PloS one. 2012;7:e36386