neuroimaging conference

8/3/2019 Neuroimaging Conference

1/48

NeuroimagingNeuroimaging of Strokeof Stroke

(Early signs on CT and MRI)(Early signs on CT and MRI)

IbrahimIbrahimAlmahbashiAlmahbashi, MD, MDAssistant ProfessorAssistant Professor

Department of RadiologyDepartment of Radiology

SanaSanaa Universitya University


2/48

IntroductionIntroduction

Stroke is a leading cause of death and disabilityStroke is a leading cause of death and disabilityworldwide.Theworldwide.The majority aremajority are ischaemicischaemic inin originorigin..

Intravenous orIntravenous or intraarterialintraarterial lysislysis are neware new

therapeutic options fortherapeutic options for ischaemicischaemic strokes.strokes.TheThe aimaim ofofthisthis newnewtherapytherapyoptionoption isis thethe rapidrapid

restorationrestoration ofofbloodblood toto hypoperfusedhypoperfused brainbrain

tissuetissue thatthat hashas notnot beenbeen irreversiblyirreversiblydamageddamaged..


3/48

IntroductionIntroductionStrictStrict selectionselection ofof patientspatients benefitsbenefits fromfrom lysislysis

therapytherapyisis necessarynecessary,, otherwiseotherwise complicationscomplications

maymayoccuroccur..TimeTimewindowwindowforfor intravenousintravenous lysislysis therapytherapyisis 33

hourshours afterafter onsetonset ofofsymptomssymptoms((practicallypracticallydifficultdifficult))

EffortEffort ofofneuroumagingneuroumagingisis toto identifyidentifypotentiallypotentiallysalvageablesalvageable brainbrain tissuetissue forfor thethe aimaim ofofextensionextensionof time windowof time windowforfor safesafe andand effectiveeffective treatment.treatment.


4/48

COMPUTED TOMOGRAPHYCOMPUTED TOMOGRAPHY Noncontrast CT is theNoncontrast CT is the most important initial diagnosticmost important initial diagnostic

study in patients with acutestudy in patients with acute strokestroke.. The basic role is to excludeThe basic role is to excludeprimary inprimary inttracerebralracerebral

haemorrhagehaemorrhage..

Exclusion of some clinically vague presented cases thatExclusion of some clinically vague presented cases that

could resemble stroke ascould resemble stroke as subdural hematomasubdural hematoma,,hemiplegic or hemisensory migrainehemiplegic or hemisensory migraine,, cerebritiscerebritis andandtumorstumors,,

The sensitivity forThe sensitivity for signssigns of ischemia on non contrastof ischemia on non contrastCT scans is within the range between 45% and 88%CT scans is within the range between 45% and 88%(mean 55.3%).(mean 55.3%).


5/48

Early signs of brain infarction on CTEarly signs of brain infarction on CT

NormalNormal CTCT findingsfindings..

HyperattenuatingHyperattenuatingarteriesarteries..

HypoattenuationHypoattenuation of grey matter structures:of grey matter structures:

Insular ribbon signInsular ribbon signDisappearing basal ganglia sign.Disappearing basal ganglia sign.

MassMass effecteffect ..


6/48

HperattenuatingHperattenuatingvessel signvessel sign

Indirect sign of acute infarction.Indirect sign of acute infarction.

Represents Stasis of flow due toRepresents Stasis of flow due to intraluminalintraluminalthrombus or embolus, mostly seen in MCA.thrombus or embolus, mostly seen in MCA.

The most early sign!The most early sign!

First 90 minFirst 90 min -- 75%75%

1212 -- 24 hours24 hours15%15%

D/D/D:CalcifiedD:Calcified atherosclerosis(higheratherosclerosis(higherdensity,disappeardensity,disappear in follow up CT).in follow up CT).


7/48

HperattenuatingHperattenuatingvessel signvessel sign

Proximal occlusion:Proximal occlusion:

M1 segment of MCAM1 segment of MCA

Distal occlusion:Distal occlusion:

M2, M3 segments ofM2, M3 segments ofMCAMCA


8/48


9/48

Prognostic value ofPrognostic value ofHperattenuatingHperattenuating

vessel signvessel sign

It has been reported that proximal hyperdense vesselIt has been reported that proximal hyperdense vessel

sign is associated with poor shortsign is associated with poor short-- and longand long--termtermprognosis in patients with ischemic strokeprognosis in patients with ischemic stroke(The patient(The patienteither dead or dependent after 3either dead or dependent after 3monthesmonthes**).Intravenous).Intravenous thrombolysisthrombolysis ineffectiveineffective

Patients with a distal hyperattenuating MCA signPatients with a distal hyperattenuating MCA sign doesdoesnot implicate poor outcome (not implicate poor outcome (independent in 64% ofindependent in 64% ofcasescases**).).Applicable toApplicable to thrombolyticthrombolytic therapytherapy

**Barber et al,Barber et al, Stroke 2001Stroke 2001


10/48

Proximal MCAProximal MCAhyperdensehyperdense signsign

6 hrs

30 hrs


11/48

Proximal MCAProximal MCAhyperdensehyperdense signsign

4hrs

72hrs


12/48

Distal MCADistal MCAhyperdensehyperdense sign(dotsign(dot

sign)sign)

6hrs

32hrs


13/48

HyperdenseHyperdense PCA signPCA sign

HyperdensityHyperdensitywithin ambient cistern.within ambient cistern.

CT marker of acuteCT marker of acute ischaemiaischaemia in territory ofin territory of

PCA.PCA.

Could beCould be assciatedassciatedwith thalamic infarction.with thalamic infarction.


14/48

4hrs

24hrs


15/48

Insular ribbon signInsular ribbon sign

Normal stripe = ThinNormal stripe = Thin

white line (gray matter)white line (gray matter)

adjacent to darker grayadjacent to darker grayline (line (subcorticalsubcorticalwhitewhite

matter)matter)

With ischemiaWith ischemia

Insular stripe is lost dueInsular stripe is lost due

toto cytotoxiccytotoxic oedemaoedema inin

grey matter loss ofgrey matter loss ofdifferentiationdifferentiation

claustrum

Island of Reil


16/48



17/48



18/48

Insular strokeInsular stroke

Minor insular strokeMinor insular stroke

2/3 ofinsulainsula involved, usually with otherinvolved, usually with otherMCA territories.MCA territories.


19/48

CytotoxicCytotoxic oedemaoedema && hypodensityhypodensityon CTon CT

Increase in tissue waterIncrease in tissue water

content by 1%content by 1% 2,5 HU decrease in2,5 HU decrease in

parenchymalparenchymal

AttenuationAttenuation

Mean attenuation decrease inMean attenuation decrease in

MCA strokeMCA stroke

50.050.0 48.4 HU 1 hour48.4 HU 1 hour

50.050.0 42.5 HU 4 hours42.5 HU 4 hours

4hrs

48hrs


20/48

Loss of basal ganglia differentiationLoss of basal ganglia differentiation

Due to occlusion ofDue to occlusion of

M1 segment of MCAM1 segment of MCAproximal toproximal to

lenticulostriatelenticulostriate

arteries.arteries.

Good adjustment ofGood adjustment of

CT window setting isCT window setting isnecessary(w:80,C:35)necessary(w:80,C:35)


21/48

Mass effectMass effect

Early mass effectEarly mass effect

includes effacementincludes effacementofofsulccisulcci andand

narrowing ofnarrowing ofSylvianSylvian

fissure.fissure.


22/48

MRIMRIProtocol:Protocol:

Conventional sequences as T1WI&T2WI haveConventional sequences as T1WI&T2WI haveno advantages over CT in the diagnosis ofno advantages over CT in the diagnosis of

hyperacutehyperacute stroke.stroke.

FLAIR is more sensitive.FLAIR is more sensitive.

DWI.DWI.

PWI.PWI.

MRA.MRA.


23/48

DWIDWI

DWI can detects stroke in early acute stages ofDWI can detects stroke in early acute stages of

stroke (0stroke (0 -- 6 hours after onset of symptoms).6 hours after onset of symptoms). Cellular energy failure leads to loss of ionCellular energy failure leads to loss of ion

homeostasis andhomeostasis and cytoxiccytoxic edemaedema, i.e., more, i.e., more

intracellular water, lessintracellular water, less extracellularextracellularwater; waterwater; water

(protons) have more restricted diffusion(protons) have more restricted diffusion

intracellularlyintracellularlythanthan extracellularextracellularhyperintensehyperintense signalsignal


24/48

DWIDWI

High signal on DWI does not necessarily meanHigh signal on DWI does not necessarily mean

acute lesion since DWI is affected by T2 effectsacute lesion since DWI is affected by T2 effectsofofvasogenicvasogenic edema in chronic infarcts ("T2edema in chronic infarcts ("T2

shineshine--through").through").

Rapid sequence, lessRapid sequence, less atrifactatrifact..

Should be correlated withShould be correlated withADCADC


25/48

DWI SEEN ALSO INDWI SEEN ALSO IN

StatusStatus epilepticusepilepticus induced by barbiturate,induced by barbiturate,

Severe hypoglycemiaSevere hypoglycemia

VenousVenous thromobosisthromobosis,, eclampsiaeclampsia ((incr.ADCincr.ADCwithwith

vasogenicvasogenic edema).edema). DWI and PWI together are quite specific forDWI and PWI together are quite specific for

ischemiaischemia


26/48

T2 DWI ADC


27/48

DWI&ADCDWI&ADC


28/48

PWIPWI

Important to detect theImportant to detect thepenumbrapenumbra

Usually correlated with DWI(PWI/DWI)Usually correlated with DWI(PWI/DWI)

If PWI/DWI mismatch>25% patientIf PWI/DWI mismatch>25% patient

applicable toapplicable to thrombolyticthrombolytic therapytherapy**

Steven R et alSteven R et al,Stroke 2007,Stroke 2007


29/48

DWIDWI


30/48

PWIPWI


31/48

MRAMRA


32/48

DWIDWI


33/48

PWIPWI


34/48

MRAMRA


35/48

DWIDWI


36/48

LacunarLacunar infarctionsinfarctions About 25% of all strokes.About 25% of all strokes.

Frequently found in basal ganglia, internalFrequently found in basal ganglia, internalcapsule, thalamus andcapsule, thalamus and ponspons..

Usually not recognized in acute stage on CT dueUsually not recognized in acute stage on CT dueto their small size.to their small size.

D/D/D:dilatedD:dilated perivascularperivascularVirchowVirchow--Robin spaces.Robin spaces.


37/48

LacnarLacnar infarctionsinfarctions


38/48

Venous infarctionVenous infarction

HighHigh pospartumpospartum incidence, trauma, dehydrationincidence, trauma, dehydration

,,pyogenicpyogenic infection,..infection,.. Clinically:headachClinically:headach, nausea, neurological, nausea, neurological

deterioration, seizures.deterioration, seizures.

May affect large sinus or small deep veins.May affect large sinus or small deep veins.

Infarctions usuallyInfarctions usuallybilateral,parasagittalbilateral,parasagittal andand

oftenoften haemorrhagichaemorrhagic..


39/48

Venous infarctionVenous infarctionNECTNECT::

Cord sign ofCord sign of

superficial cerebralsuperficial cerebral

vein.vein.


40/48

Venous infarction cont. Venous infarction cont.

NECTNECT

CorticalCortical oror subcorticalsubcortical

hypodensityhypodensity((usuallyusuallybilateralbilateral).).


41/48


NECTNECT

CorticalCortical oror subcorticalsubcortical

hyperdensityhyperdensity,, ifif

haemorrhagichaemorrhagic,,

((usuallyusuallybilateralbilateral).).


42/48


CECTCECT::

EmptyEmptydeltadelta signsign..


43/48

Venous infarctionVenous infarction MRIMRI

Loss of the normal signal void within theLoss of the normal signal void within the thrombosedthrombosedsinus in T2WI, replaced bysinus in T2WI, replaced by hyperintensityhyperintensitythatthat

represents the thrombus.represents the thrombus.

HypointensityHypointensityin T1WI andin T1WI and hyperintensityhyperintensityin T2WI inin T2WI incortical orcortical or subcorticalsubcortical areas in cases of pure infarction.areas in cases of pure infarction.

In cases ofIn cases ofhaemorrhagehaemorrhage the signals depend on the agethe signals depend on the age

ofofhaematomahaematoma..


44/48

Venous infarction MRIVenous infarction MRI


45/48

MRVMRV


46/48

CONCLUSIONCONCLUSION CT scan is the standard of care in acute strokeCT scan is the standard of care in acute stroke imaging.Itimaging.It isis

widely available, fast and practical.widely available, fast and practical.

Early CT signs of stroke are of therapeutic and prognostic valueEarly CT signs of stroke are of therapeutic and prognostic valueand can indicate specific arterial occlusion.and can indicate specific arterial occlusion.

DWI in MRI is more sensitive in theDWI in MRI is more sensitive in the hyperacutehyperacute stage of strokestage of strokebut should be used with ADC.but should be used with ADC.

MRI is also better in clarifyingMRI is also better in clarifyingcerebellarcerebellar and brain stemand brain steminfarctions.infarctions.

PWI/DWI mismatch on MRI can select patient forPWI/DWI mismatch on MRI can select patient for thrombolysisthrombolysis

therapy beyond currently known time window.therapy beyond currently known time window.


47/48

Brain imaging can reduce health cost if it preventsBrain imaging can reduce health cost if it prevents

the disability and death of stroke victims.the disability and death of stroke victims.


48/48

Thank youThank you

neuroimaging conference

Documents