CT Angiography & CT Perfusion in Management of Acute Stroke

1. 1
CT Angiography and
CT Perfusion in the
Management of Acute
Stroke
Stroke –past
„„good outcome with IV good outcome with IV tPA(mRStPA(mRS00--1): 1): 39%39%vs. vs. 26%26%
11
„„most patients arrive too late most patients arrive too late (>3 hrs for NINDS)(>3 hrs for NINDS)
„„currently, only currently, only 0.60.6--1.8%1.8%of strokes get IV tPA of strokes get IV tPA
2,32,3
NINDS NEJM 1995
1
,
Katzan JAMA 2000Katzan JAMA 2000
2
,,
Qureshi NRS 2005Qureshi NRS 2005
3
Stroke –present
Odds Ratio for Favorable OutcomeOdds Ratio for Favorable Outcome
„„IV IV tPAtPAexclusions / contraindicationsexclusions / contraindications
Stroke –present
1. > 3 hrs from stroke onset
2. 80 > age > 18
3. pregnancy (up to 10 days postpartum)
4. “symptoms suggestive of SAH” – despite negative CT
5. “rapidly improving or minor symptoms”
6. “seizure at onset of stroke”
7. ever: →history of intracranial hemorrhage
8. within 3 mo: →stroke, serious head trauma, intracranial surgery
9. within 21d: →GI/urinary/pulmonary hemorrhage
10. within 14d: →major surgery
11. within 7d: →arterial puncture at a non-compressible site
12. SBP > 185 mmHg or DBP > 110 mmHg
13. aggressive treatment required to reduce BP to specified limits
14. current use of anticoagulants (or recent, with PT > 15s)
15. use of heparin within 48hrs and elevated PTT
16. platelets < 100,000
17. glucose < 50 or > 400 mg per deciliter
18. brain tumour, abscess, aneurysm, AVM
19. bacterial endocarditis
20. known bleeding diathesis – includes renal, hepatic insufficiency
21. etc…
„„IV IV tPAtPAis less effective for severe strokes is less effective for severe strokes
11
„„NIHSS NIHSS ≥≥10: 75% decreased chance of good outcome10: 75% decreased chance of good outcome
„„NIHSS > 20: only 8% will attain NIHSS=1 after IV NIHSS > 20: only 8% will attain NIHSS=1 after IV tPAtPA
„„
IV IV tPAtPAis less effective for large vessel occlusions is less effective for large vessel occlusions
2,32,3
„„ICA recanalization rate is 1/3 that of MCAICA recanalization rate is 1/3 that of MCA
„„tandem ICA/MCA has poor recanalization & bad prognosistandem ICA/MCA has poor recanalization & bad prognosis
„„
IV IV tPAtPAis relatively slowis relatively slow--acting acting
4,54,5
„„TCD over 6hrs TCD over 6hrs →→30% 30% recanrecan(of which (of which ¾¾are within 1hr are within 1hr tpatpa))
„„angio 1hr after angio 1hr after tPAtPA→→1/10 ICA/proximal MCA, 1/3 distal MCA1/10 ICA/proximal MCA, 1/3 distal MCA
1: NINDS Stroke 1997; 28:2119–2125
2: LInfante Stroke 2002; 33:20662: LInfante Stroke 2002; 33:2066--20712071
3: 3: RubieraRubieraStroke 2006; 37:2301Stroke 2006; 37:2301--23052305
4: 4: ChristouChristouStroke 2000; 31:1812Stroke 2000; 31:1812--18161816
5: Lee 5: Lee Stroke 2007; 38:192-3
Stroke –present
““Time is brainTime is brain””
„„typical supratentorial large vessel stroke: ~54ml brain is typical supratentorial large vessel stroke: ~54ml brain is
lost over ~10 hrslost over ~10 hrs
„„per hour:per hour:830 billion synapses, 120 million neurons, 447 830 billion synapses, 120 million neurons, 447
miles of myelinated miles of myelinated fibrefibrelostlost
„„each each hourhour, brain effectively ages 3.6 , brain effectively ages 3.6 yearsyears
Saver, Stroke2006; 37:263

2. 2
1987
IV tPA
1996
IV tPA
2000
Stent
2003
Cypher
1993
PTCA
2004
MERCI Retriever
1999
PROACT II
Treatment of Acute Stroke
Treatment of Acute MI
???
Multimodal
Revascularization
Stroke –future?
now.
today
„„Thrombolytics:Thrombolytics: →→Alteplase, RetavaseAlteplase, Retavase
„„GIIb/IIIa inhibitors:GIIb/IIIa inhibitors:→→Reopro, IntegrilinReopro, Integrilin
„„Mechanical disruption:Mechanical disruption:→→microwire / snaremicrowire / snare
„„Clot retrieval:Clot retrieval: →→MERCI, PenumbraMERCI, Penumbra
„„Ultrasound Catheter:Ultrasound Catheter: →→EKOSEKOS
„„Angioplasty / StentingAngioplasty / Stenting→→Gateway / WingspanGateway / Wingspan
Stroke –new tools
Case example:
ƒ45 yo male
ƒacute LMCA stroke
ƒR paretic, R hemianopic, R facial droop, dysphasic, dysarthric.
ƒNIHSS = 15
CT: early left caudate head, basal ganglia infarct
CTP:
↑↑MTT, ↓CBF, ↑CBV
Interpretation:
small caudate and
frontopolar infarcts,
surrounded by large
(but salvageable)
ischemicpenumbra…
Flow
Volume
Transit Time

3. 3
CTA: LM1 occlusion (w/distal collateral) CTA: LCCA/inominate stenosis
AP:
Sag:
LCCA origin severe stenosis, 5F sim2 finally pops in but is occlusive (static dye column) T-occlusion equivalent: proximal LA1, LM1 occluded, poor collateralization
All-star 0.014 wire maintains access to LCCA, pigtail arch run shows severe origin stenosis
1. Aviator 6x30mm over
All-star wire, LCCA
origin angioplastied
2. Sim2 back over All-
star wire into distal
LECA
3. All-star wire then
exchanged for 0.035
stiff exchange
glidewire
4. Sim2 swapped out for
7F concentric balloon
guide over stiff
exchange wire, parked
in LCCA
5. Concentric guide
catheter taken to distal
cervical LICA
6. LMCA occlusion
crossed with 18L
Concentric
microcatheter over
Transend microwire…
Cross LM1 occlusion with MERIC 18L microcatheter over transend
AP Lateral

4. 4
Deploy MERCI L5 retriever
AP Lateral
Clot retreived, flow restored
AP Lateral
AP
Pre
Post
AP Lateral
Post –Arch MRA: LCCA stenosis better, inominate as before, will need txlater
„„Thrombolytics: Alteplase, RetavaseThrombolytics: Alteplase, Retavase
„„GIIb/IIIaGIIb/IIIainhibitors: inhibitors: ReoproReopro, , IntegrilinIntegrilin
„„Mechanical disruption: microwire/snareMechanical disruption: microwire/snare
„„Clot retrieval: MERCI (X6, L5, variants)Clot retrieval: MERCI (X6, L5, variants)
„„Ultrasound assisted Catheter: EKOSUltrasound assisted Catheter: EKOS
„„Balloon AngioplastyBalloon Angioplasty
„„Primary StentingPrimary Stenting
IA Thrombolysis: New Tools

5. 5
To select out To select out
patients with patients with viableviable
brain tissue at risk brain tissue at risk
that can be treated that can be treated
with the with the optimaloptimal
tool for tool for
revascularisationrevascularisation
GOAL:
HOW?
New-generation CTA/CTP= anatomy+physiology
1. faster: <5 min total acquisition time
2. less motion artifact
3. less dye (CTA+CTP <120ml)
→<50ml with 320-slice!
4. CTA
(arch to vertex) :
• lesion presence/absence/location
• lesion accessibility
• a priori knowledge = no guessing!
5. CTP
:
• absolute numbers for CBF, CBV
• 4-8 slices, + post-fossa coverage
→full coverage with 320-slice!
•CBF ≈penumbra+core; CBV ≈collateral supply
• CBF/CBV mismatch = salvageable penumbra!
Imaging for stroke intervention
13.3±3.75 1.12 ±0.37
threshold=31.3
sensitivity=97.0%
specificity=97.2%
accuracy=97.1%
for CBFxCBV and
subsequent stroke
25.0±3.8237.3±5.01
2.15±0.431.78±0.30
FLOW VOLUME
CBFxCBV
Murphy, B. D. et al. Radiology 2008;247:818-825 Murphy, B. D. et al. Radiology 2008;247:818-825

6. 6
Figure 3: Scatterplot shows mean CBV versus mean CBF in penumbra and infarct regions in patients with acute stroke and
confirmed recanalization at 24 hours (dashed line represents CBF×CBV = 8.14)
Murphy, B. D. et al. Radiology 2008;247:818-825
- 40 patients, median NIHSS=16, 19 received iv-tpa
- compared initial CTP/CTA and day #3 postop MRI/MRP
- reperfusion defined as normalization of ≥80% area with increased MTT
Regions with infarction (based upon DWI+ADC) at day #3 compared with CBV maps
on initial CTP →in hypoperfused areas ( ↓↓CBF, ↑↑MTT), does CBV predict
eventual infarction?
94%(go on to
infarct)63%(go on to
infarct)94%(go on to
infarct)No reperfusion
3%
(go on to
infarct)41%(go on to
infarct)97%(go on to
infarct)Withreperfusion
HighNormalLowCBV
rCBF prediction of symptomatic ICH
following IA treatment for MCA occlusion
Gupta 2006 Stroke 37:2526
~ 13 ml
per 100g/min
~ 1/3 MCA
territory
CTP parameters can predict hemorrhage
CTP in posterior circulation!
CBF CBV MTT DWI
Acute Stroke
CTA / CTP
large vessel occl. (ICA, M1/M2, A1, VA/BA)
large ischemic penumbra > infarct
large stroke (NIHSS≥10)
0-3 hr
IV tPA IA TxIA Tx ± bridging IV tPA no acute thrombolysis,
later medical or surgical
stroke prophylaxis
>3 hr
large vessel occl. (ICA, M1/M2, A1,VA/BA)
large ischemic penumbra > infarct
large stroke (NIHSS≥10)
yes no yes no
Stroke Algorithm

7. 7
SUMMARY
ƒCTP is available and powerful:
ƒTransit time= very sensitive (but not specific)
ƒFlow= penumbra pluscore
ƒVolume= penumbra vscore (collateral supply)
ƒpreserved→penumbra (still salvageable)
ƒdecreased→core (dead)
ƒCBF/CBV = crude “risk/reward” ratio
ƒonset often unclear →CT perfusion = more accurate
physiological data
ƒperfusion beats onset
POD#1 DWI: frontopolar, caudate, basal ganglia infarcts (predicted by CTP), but
large LMCA territory salvaged
POD#1 FLAIR: small caudate head, basal ganglia, frontopolar infarcts
POD#2 CT
Case example:
ƒ83 yo male
ƒacute right hemisphere stroke
ƒleft plegic, R gaze preference, L facial droop, dysarthric
ƒNIHSS > 10
ƒlast normal > 14hrs ago
ƒpast medical history = paroxysmal atrial fibrillation
(discovered on this admission)

8. 8
preopCBF preopCBV
Emergency
CT perfusion:
Low CBF but preserved
CBV →stroke is still
salvageable.
residual
clot
thrombectomy and lytics→inferior division open, residual clot in superior division
balloon angioplasty→superior division now also open
PostPre
preopCBF preopCBV
Case example:
ƒ33 yo female
ƒacute right carotid stroke
ƒleft hemiplegia, facial droop, dysarthria, hemianopia,
neglect, decreased left body sensation, drowsy, fixed gaze
deviation to right.
ƒNIHSS = 16
ƒonset > 4 hrs
ƒpast medical history = smoker, oral contraceptive pills
CBF CBVTTP
INITIAL CTP:
-Very low blood flow
-Very slow blood flow
-Preserved blood volume
-BUT: > 4hrs onset

9. 9
Complete right internal carotid artery occlusion →no intracranial blood flow microcatheter run shows distal blood vessels remains patent
MERCI thrombectomy opens distal carotid and proximal middle cerebral artery,
balloon angioplasty opens distal middle cerebral artery
MRI few days later…
Case example:
ƒ76 year old female
ƒFound 2:30 am at outside institution with stroke, onset
unknown
ƒRapidly transferred to tertiary-care institution.
ƒWhen seen, unable to move anything except eyes
ƒrapidly loosing consciousness →crash intubated in ED
ƒNIHSS = 30
Mid-BA occlusion

10. 10
Big Problem…
Bigger Problem…?
Access is going to be tough!!!
arm
a rm
Pooled NASCET, ECST, VA309 results Lancet 2003,361(9352):107
Case example #1:
ƒ70 yo male
ƒacute LMCA stroke
ƒdriving →swerved off road →min. responsive on scene
ƒright plegic, aphasic, fixed gaze to left in ED
ƒNIHSS = 22
ƒonset <1.5 hrs
ƒPMH = HTN, NIDDM, dyslipidemia, atrial flutter, on ASA
hyperdense sign

11. 11
CBF CBV TTP
13.6 x 0.9 = 12.2
CBV reduction matches
reduction in CBF →no
collateral reserve, no
penumbra, infarct already
well established.
Case example #5:
ƒ70 yo male
ƒacute RMCA stroke
ƒinitial NIHSS=12 in ED, worsened to > 18 →intubated
ƒonset > 6 hrs
ƒPMH = MI, CABG, PVD, HTN, NIDDM, previous L parietal
subcortical stroke
CT (pre)
CBF CBV TTP
CTP (pre)

12. 12
Treatment:
ƒAngio = RMCA bifurcation occlusion, ant. temporal open
ƒRetavase 2mg M1
ƒRetavase 1mg M2
inf
ƒwire both M2’s
ƒMerci M2
sup
x2
Pre Post
CT (POD#1)
Outcome:
ƒTIMI-3 M1/M2’s
ƒdistal branch of inferior M2 remained occluded
ƒR basal ganglia ICH, R parietal infarct
ƒrest of MCA territory spared
ƒdischarged 17 days later to rehab, NIHSS=16
ƒreturn w/urosepsis one month later →no sig improvement
CT 44 days later…NIHSS still 16.
CTP keypoints:
1. TTP/MTT is very sensitive – but not specific
2. CBV distinguishes infarction vs. ischemic penumbra (dead vs. salvageable brain)
3. Areas at risk for hemorrhage post-thrombolysis can be predicted
4. Crude risk/benefit ratio = CBV / CBF deficit
Bottom line = physiological imaging is real and powerful…CTP does not lie!

13. 13
SUMMARY
ƒCTP is available and powerful:
ƒTransit time= very sensitive (but not specific)
ƒFlow= penumbra pluscore
ƒVolume= penumbra vscore (collateral supply)
ƒpreserved→penumbra (still salvageable)
ƒdecreased→core (dead)
ƒCBF/CBV = crude “risk/reward” ratio
ƒonset often unclear →CT perfusion = more accurate
physiological data
ƒperfusion beats onset