Advances in Diagnostic Imaging

of Acute Ischemic Stroke

CT or MRI

Prof. Pham Minh Thong M.D

Radiology Department

Bach Mai Hospital

Introduction

• Ischemic: 80% of stroke

• Third leading cause of dead in developed country

• Cardiovascular disease, diabetes,…

• 2025: prediction of 1.2 millions patients/year

• In Viet Nam, stroke is top cause of Death (account

for 18% - 2008)

“Time is brain”!

Diagnostic Tools

• Multi choices in diagnosis

• CT Scanner -> MRI

• Perfusion -> Multiphase

CT SCANNER

• “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

CT Non-contrast

• Rule out the hemorrhage

• Identify ischemic lesion

• Tips:

• Change the window level

–C: 8

–W: 32

ASPECTS

• ≥ 6: favorable clinical outcome*

*Stroke, 2008. 39(8): p. 2388-2391

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

CT Angiography

MIP (Single phase) VRT

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)

CT

Perfusion

MRI

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

- Rule out hemorrhage

- Identify cerebral microbleeding

-> risk factor of bleeding after

treatment

T2*

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

Identify occlusion site

T2*

MRI TOF 3D

• ≥ 6: favorable clinical outcome*

L

ASPECTS

• ≥ 8: favorable clinical outcome*

Pc-ASPECTS

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

MTT: mean transit time, CBF: Cerebral Blood Flow

TTP: Time to peak, CBV: Cerebral blood volume

MTT

CBVCBF

TTP

DWI PERFUSION - MECHANISM

MRI Perfusion

Match PW/DW -> no

penumbra -> no indication

of treatment

Mismatch PW/DW

-> good indication

for treatment

Case

Before

DWI DWIPWI PWI

After

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

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

New techinque

• 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

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 2Menon et al., (2015). Neuroradiology, 000 (0).

Evaluation

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

Evaluation scale

Điêm Đanh gia (khi so sanh vơi ban câu bên bênh vơi bên lanh)

0 Không quan sat thât bât ky nhanh mach mau nao đi vao vung nhôi mau tai

bât ky phase nao

1 Co môt vai nhanh mach mau nho đi vao vung nhôi mau tai bât ky phase nao

2 Châm 2 phase hiên hinh mach mau vung ngoai vi VA giam đâm đô-tôc đô

ngâm thuôc, HOĂC châm 1 phase nhưng co vung không co mach mau

3 Châm 2 phase hiên hinh mach mau vung ngoai vi, HOĂC châm 1 phase

nhưng sô lương mach mau trong vung nhôi mau giam

4 Châm 1 phase hiên hinh mach mau vung ngoai vi, nhưng đâm đô va tôc đô

ngâm thuôc thi tương tư

5 Không co châm phase, quan sat thây ngay cac nhanh mach mau bang hê đi

vao binh thương hoăc nhiêu hơn trong vung nhôi mau

• 0-3: ngheo bang hê (poor), 4: vưa (moderate), 5: tôt (good)

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

ESCAPE

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%

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

• Right 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

•Left hemiplegia, unconscious, G~13pt, NIHSS = 19

PHASE 1 PHASE 2 PHASE 3

• Multiphase score ~ 4 point (good collateral)

Multiphase

TTP

(Time to Peak)

CBF

(Cerebral Blood Flow)

CBV

(Cerebral Blood Volume)

• Mismatch > 35%

Perfusion

DSA (19h50’ – 20h10’)

• Solitaire 6/20: 1 times

• TICI 3

Follow up

• G ~ 15pt

• NIHSS ~ 6pt

• mRS ~ 2 after 2 days

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)

PHASE 1 PHASE 2 PHASE 3

Multiphase

• Multiphase score ~ 2 point (poor collateral)

DSA (15h15’ – 15h57’)

• Solitaire 6/30: 4 times

• TICI 3

MRI follow up

• G 15pt

• NIHSS ~ 9pt

• mRS ~ 4 after 2 weeks

Protocol changes

• 1) Treatment:

– IV + MT in the first 4.5 hours

– After 4.5 hours, mechanical thrombectomy only

– No later than 6 hours

• 2) Good patients selection:

– NIHSS: from 6 (to 25)

– Age ≥ 18 (to 80)

– ASPECTS ≥ 6

• 3) Big arterial Occlusion (M1, ICA)/ Good collateral

Solitaire

(Priority)

+

Good combination

IV r-tpA (For < 4.5hrs but don’t wait, do the

Mechanical Thrombectomy

right after transfusion)

Protocol in BM Hospital from 2012-15

Administered to the Emergency Department (10 mins)

First aid with clinical examination and test (10 mins)

CT/MRI (non contrast, angio, multiphase/ perfusion) (15mins)

Hemorrhage

Rule out

Ischemic with evidence of

big arteries occlusion

IR room (30-45 mins)

Conclusion

• CT Scanner noncontrast and MSCT is very important

and always/strongly recommended in AIS before any

treatment – easy and accessible in all hospital

• DWI/PW: good information but need more trial to prove

its evidence and cut-off volume in prognosis

• CT Multiphase: new choice and simple, also need more

trials and time

• MRI: unknown time window, follow-up patient

THANK YOU FOR YOUR ATTENTION