Advances in Diagnosis of Acute Ischemic Stroke

Prof. Pham Minh Thong Bach Mai University Hospital

Hanoi-Viet Nam

Journées Francophones d’Imagerie Médicale 14th Annual Meeting, Hanoi, nov 2015

Introduction

•  Ischemic: 80% of stroke

•  3rd leading cause of dead in United States

•  2025: prediction of 1.2 millions patients/year •  In Viet Nam, stroke is top cause of Death (account

for 18% - 2008)

•  Cardiovascular disease, diabetes… 2

Diagnostic Tools

•  Multi choices in diagnosis

•  CT Scanner -> MRI •  Perfusion -> Multiphase

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CT SCANNER

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•  “Emergency imaging of the brain is recommended before any specific treatment for AIS. Non-enhanced CT will provide the necessary information for initial treatment of IV r-tPA (Class I; level of Evidence A - same as 2013)*”

*AHA/ASA-stroke guide line 2015 5

CT Non-contrast 6

•  Rule out the hemorrhage •  Identify ischemic lesion

•  Tips: • Change the window level

– C: 8 – W: 32

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8

ASPECTS

•  ≥ 6: favorable clinical outcome* *Stroke, 2008. 39(8): p. 2388-2391 9

CT Angiography (MSCT)

•  “A non-invasive intracranial vascular study is strongly recommended. If not possible at the time of initial imaging, r-tPA should done first then try vascular imaging as quickly as possible (Class I, level A - New)”

*AHA/ASA-stroke guide line 2015 10

CT Angiography

MIP (Single phase) VRT 11

CT Perfusion •  “The benefit of CT perfusion, DWI/perfusion-weighted

imaging for selecting patients (ASPECTS<6…) for endovascular therapy are unknown (Class IIb; level C - New). Further randomized, controlled trials should be done*”

*AHA/ASA-stroke guide line 2015

Lesions = Core (irreversible )+ penumbra (reversible)

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CT Perfusion

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MRI

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MRI protocol

•  T2*: rule out hemorrhage + identify cerebral microbleeding

•  DWI: core of infarction •  FLAIR: parenchymal lesion/ absence of “flow voids” in

the occluded artery

•  TOF 3D: arterial occlusion site

•  PW: if possible

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- Rule out hemorrhage

- Identify cerebral microbleeding

-> risk factor of bleeding after treatment

T2*

Kidwell Stroke 2002; Nighoghossian Stroke 2002; Derex Cerebrovasc Dis 2004 16

Identify occlusion site

T2*

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MRI TOF 3D

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•  ≥ 6: favorable clinical outcome*

L

ASPECTS

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•  ≥ 8: favorable clinical outcome*

Pc-ASPECTS

*Stroke, 2008. 39(9): p. 2485-90 21

Acute stage < 6h 22

Acute stage (6-24h) 23

Early sub-acute stage: 48hrs - 3 weeks 24

Late sub-acute stage 25

Chronic stage 26

MTT: mean transit time, CBF: Cerebral Blood Flow

TTP: Time to peak, CBV: Cerebral blood volume

MTT

CBV CBF

TTP

DWI PERFUSION - MECHANISM

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MRI Perfusion

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Match PW/DW -> no penumbra -> no indication of treatment

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Mismatch PW/DW

-> good indication for treatment

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Case Before

DWI DWI PWI PWI

After

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CT Scanner

–  Low sensitivity; PW only for anterior

circulation (64 slices)

–  2 times of contrast (Angio & PW)

–  Can not discover micro bleeding

–  Quick

–  Patient unstable -> fast scan

–  Widespread access

–  In case of contraindication with MRI

(Stent, pacemaker…)

MRI

•  Very high Sv & Sp; PW for

whole brain

•  Only 1 time of contrast (PW)

•  Identify micro bleeding

•  A little slower but acceptable

•  Patient need to be very stable

•  Mostly in big hospital

•  No radiation

Comparison

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Role of DWI&PW image

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AJNR, 2002

•  High sensitivity and specificity for detecting AIS •  DWI and CBV best predict final volume

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•  DWI = irreversible lesion = core of infarction •  Bigger core, worse outcome

•  In the MCA occlusion, core volume in DWI > 100cm3 -> no indication of treatment (>1/3 territory of MCA) •  >70cm3: poor prognosis even rapid recanalization*

•  <70cm3: good outcome (64%) after quick recanalization •  Other studies**:

–  V <16cm3: good outcome

–  V >36cm3: bad result

DWI

(*) Stroke,2009.40:p.2046-2054 (**)Stroke,2011.42(5):p.1251-4.

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•  Sn of PW ~[74-84%], Sp of PW ~[96-100%] •  Mismatch DW/PW = penumbra area

•  (PW – DW)/ DW x 100% > 20% -> significant difference*

DWI/PW

(*) EPITHETstudy-Stroke,2009.40:p.2046-2054

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•  N = 132 •  Volume of core in DWI: 43 ± 69,9cm3

p=0.00139 p=0.00028 (Fisher exact test)

In our research*

(*) NguyenDuyTrinh,PhamMinhThong2014

Time (min) <180

(n=76)

180-360

(n=29)

>360

(n=18)

V (cm3)

34,7 ± 54,1 55,2 ± 57,6 86,9 ± 114

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Volume

V<30cm3 V>30cm3 N

mRS ≤ 2 69 4 73

mRS > 2 21 37 58

Correlation between Volume of infarction and clinical recovery

•  V<30cm3: good prognosis

p < 0.05

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Volume Before treatment

(cm3) After treatment

(cm3)

P

Quick

recanalization(n=47) 42,3 ±54 47,4 ±54,9 0,912

Late/failed

recanalization (n=26) 39,1± 49,8 91,8±81,8 0,01559

Follow up after treatment

•  Good recanalization -> no change in infarction volume -> save penumbra tissue

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Case 1a •  Male patient, 53 years old •  Normal history •  Suddenly right hemiplegia •  Administered to hospital within 2nd hours •  NIHSS = 16 •  Left ICA occlusion, ASPECTS~8

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TICI = 3

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mRS = 1

Before

After

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Case 1b - Woman 75yo, 1st hour - M1 occlusion, large penumbra - Good recanalization - mRS~1pt after 3 months

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Problem

•  Some patients having less penumbra -> good outcome

•  In contrast, others who have good penumbra -> poor outcome

-> Other factors affect the clinical recovery (collateral?) -> Need a new method to evaluate salvageable brain quickly, reliably and widely available

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New update

•  CT Angiography Multiphase is a good choice •  Simple procedure

•  Just published in 2015

•  Data from PRoveIT (Menon et al) •  N = 147, comparison between CT Multiphase, single

phase and CT Perfusion

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Protocol •  Non contrast first then multiphase

•  Phase 1: •  Evaluate the carotid and brain circulation •  Double scan with contrast, then subtraction algorithm

•  Phase 2: •  Just only the brain •  Time for moving table+scan •  Total 8sec

•  Phase 3 •  Similar to phase 2

Menon et al., (2015). Neuroradiology, 000 (0). 47

Evaluation

Menon et al., (2015). Neuroradiology, 000 (0). 48

Evaluation

Menon et al., (2015). Neuroradiology, 000 (0). 49

Evaluation scale Điểm Đánh gia (khi so sánh với bán cầu bên bệnh với bên lành)

0 Không quan sát thất bất ky nhánh mạch máu nào đi vào vùng nhồi máu tại bất ky phase nào

1 Có một vài nhánh mạch máu nho đi vào vùng nhồi máu tại bất ky phase nào

2 Chậm 2 phase hiện hình mạch máu vùng ngoại vi VÀ giảm đậm đô-tốc đô ngấm thuốc, HOẶC chậm 1 phase nhưng có vùng không có mạch máu

3 Chậm 2 phase hiện hình mạch máu vùng ngoại vi, HOẶC chậm 1 phase nhưng sô lượng mạch máu trong vùng nhồi máu giảm

4 Chậm 1 phase hiện hình mạch máu vùng ngoại vi, nhưng đậm đô va tốc đô ngấm thuốc thi tương tư

5 Không có chậm phase, quan sát thấy ngay các nhánh mạch máu bàng hê đi vào bình thường hoặc nhiều hơn trong vùng nhồi máu

•  0-3: nghèo bàng hệ (poor), 4: vừa (moderate), 5: tốt (good) 50

Advantages

•  Quick and save the time, only 10-20 sec more after the MSCT Single phase

•  1 time inject contrast material >< twice in MSCT perfusion

•  Widely available and easy to perform (no complicated mathematical algorithm post process - only MIP reconstruction in 3 phases compared to perfusion reconstruction)

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Case 3 •  Male, 78 yo •  Diabetes •  Administered in 2nd hours •  Left hemiplegia •  NIHSS = 15 •  Perfusion: match

ischemic ~ CBV -> not favorable penumbra area -> no indication

•  BUT Multiphase score = 4 -> moderate collateral

•  Good recanalization after endovascular therapy -> good result after (mRS ~ 2)

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•  Menon et al., (2015). Neuroradiology, 000 (0).

Multi >< Single Phase

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Recommendation

•  CT Multiphase score ≥ 4 -> good collateral

•  CT Multiphase score ≤ 3 -> poor collateral

•  New method, useful in ESCAPE but need more trials to proved its value

•  Now applied in Bach Mai hospital protocol

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ESCAPE

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Design and results

•  Methods –  IV >< IV + MT in the first 4.5 hours –  238/316 received rt-PA with 118 control >< 120 intervention –  Treatment up to 12 hours with anterior circulation occlusion –  NO large infarct core (ASPECTs < 6), NO poor collateral (<50%

filling pial artery of the MCA in the CT Multiphase)

•  Results –  Stop early because of the efficacy –  Times from CT non contrast to groin puncture: 60mins/ to first

reperfusion: < 90 mins –  mRS 0-2: 29.3% >< 53% -> Thrombectomy is better –  Mortality: 19% >< 10.4% –  Symptomatic hemorrhage: 2.7% >< 3.6%

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Bach Mai hospital protocol

•  Noncontrast: 3.71 sec •  Phase 1:

•  Scantime 6.2s •  Delay (contrast injection) 14 sec •  Scantime 6.2 sec

•  Phase 2: •  Total time 5 + 3.71 sec

•  Phase 3: •  Total time 5 + 3.71 sec

-> Only 17 sec more 57

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•  Left M1 occlusion (19h00’ ASPECTS ~ 8 point)

Case 2a • Male, 75 years old, history of cardiac coronary disease • Stroke during hospitalizing time (17h30’) due to chest pain • Right hemiplegia, unconscious, G~13pt, NIHSS = 19

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PHASE 1 PHASE 2 PHASE 3

•  Multiphase score ~ 4 point (good collateral)

Multiphase

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TTP(Time to Peak)

CBF(Cerebral Blood Flow)

CBV(Cerebral Blood Volume)

•  Mismatch > 35%

Perfusion

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DSA (19h50’ – 20h10’)

•  Solitaire 6/20: 1 times •  TICI 3 62

Follow up

•  G ~ 15pt •  NIHSS ~ 6pt •  mRS ~ 2 after 2 days

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Case 2b • Female, 57 years old; Atrial fibrillation, still using anticoagulant • Administered to BM hospital in 2nd hours (13h15’->14h30’) • Left hemiplegia, NIHSS = 18

•  Right ICA occlusion (14h45’ ASPECTS ~ 6 point) 64

PHASE 1 PHASE 2 PHASE 3

Multiphase

•  Multiphase score ~ 2 point (poor collateral) 65

DSA (15h15’ – 15h57’)

•  Solitaire 6/30: 4 times •  TICI 3

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MRI follow up

•  G 15pt •  NIHSS ~ 9pt •  mRS ~ 4 after 2 wks

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Conclusion •  CT Scanner noncontrast and MSCT is very important

and always/strongly recommended in AIS (in new guideline 2015) before any treatment – easy and accessible in all hospital

•  CT Multiphase: new choice, simple and beneficial than Perfusion and single phase

•  MRI only in big hospital, very useful especially in unknown time stroke patients

•  DWI/PW: good information but need more trial to prove its evidence and cut-off volume in prognosis

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THANK YOU FOR YOUR ATTENTION!