neuroimaging conference
TRANSCRIPT
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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
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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..
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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.
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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%).
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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 ..
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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).
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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
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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
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Proximal MCAProximal MCAhyperdensehyperdense signsign
6 hrs
30 hrs
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Proximal MCAProximal MCAhyperdensehyperdense signsign
4hrs
72hrs
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Distal MCADistal MCAhyperdensehyperdense sign(dotsign(dot
sign)sign)
6hrs
32hrs
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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.
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4hrs
24hrs
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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
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Insular ribbon signInsular ribbon sign
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Insular ribbon signInsular ribbon sign
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Insular strokeInsular stroke
Minor insular strokeMinor insular stroke
2/3 ofinsulainsula involved, usually with otherinvolved, usually with otherMCA territories.MCA territories.
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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
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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)
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Mass effectMass effect
Early mass effectEarly mass effect
includes effacementincludes effacementofofsulccisulcci andand
narrowing ofnarrowing ofSylvianSylvian
fissure.fissure.
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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.
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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
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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
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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
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T2 DWI ADC
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DWI&ADCDWI&ADC
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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
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DWIDWI
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PWIPWI
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MRAMRA
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DWIDWI
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PWIPWI
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MRAMRA
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DWIDWI
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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.
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LacnarLacnar infarctionsinfarctions
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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..
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Venous infarctionVenous infarctionNECTNECT::
Cord sign ofCord sign of
superficial cerebralsuperficial cerebral
vein.vein.
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Venous infarction cont. Venous infarction cont.
NECTNECT
CorticalCortical oror subcorticalsubcortical
hypodensityhypodensity((usuallyusuallybilateralbilateral).).
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Venous infarction cont. Venous infarction cont.
NECTNECT
CorticalCortical oror subcorticalsubcortical
hyperdensityhyperdensity,, ifif
haemorrhagichaemorrhagic,,
((usuallyusuallybilateralbilateral).).
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Venous infarction cont. Venous infarction cont.
CECTCECT::
EmptyEmptydeltadelta signsign..
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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..
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Venous infarction MRIVenous infarction MRI
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MRVMRV
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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.
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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.
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Thank youThank you