1. 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

2. 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

3. Diagnostic Tools
• Multi choices in diagnosis
• CT Scanner -> MRI
• Perfusion -> Multiphase
3

4. CT SCANNER
4

5. • “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

6. CT Non-contrast
6

7. • Rule out the hemorrhage
• Identify ischemic lesion
• Tips:
• Change the window level
– C: 8
– W: 32
7

8. 8

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

10. 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

11. CT Angiography
MIP (Single phase) VRT 11

12. 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)
12

13. CT
Perfusion
13

14. MRI
14

15. 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
15

16. - Rule out hemorrhage
- Identify cerebral microbleeding
-> risk factor of bleeding after
treatment
T2*
Kidwell Stroke 2002; Nighoghossian Stroke 2002; Derex Cerebrovasc Dis 2004
16

17. Identify occlusion site
T2*
17

18. MRI TOF 3D
18

19. 19

20. • ≥ 6: favorable clinical outcome*
L
ASPECTS
20

21. • ≥ 8: favorable clinical outcome*
Pc-ASPECTS
*Stroke, 2008. 39(9): p. 2485-90
21

22. Acute stage < 6h
22

23. Acute stage (6-24h) 23

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

25. Late sub-acute stage 25

26. Chronic stage
26

27. MTT: mean transit time, CBF: Cerebral Blood Flow
TTP: Time to peak, CBV: Cerebral blood volume
MTT
CBVCBF
TTP
DWI PERFUSION - MECHANISM
27

28. MRI Perfusion
28

29. Match PW/DW -> no
penumbra -> no indication
of treatment
29

30. Mismatch PW/DW
-> good indication
for treatment
30

31. Case
Before
DWI DWIPWI PWI
After
31

32. 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
32

33. Role of DWI&PW image
33

34. AJNR, 2002
• High sensitivity and specificity for detecting AIS
• DWI and CBV best predict final volume
34

35. • 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.
35

36. • 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
(*) EPITHET study-Stroke, 2009. 40: p. 2046-2054
36

37. • N = 132
• Volume of core in DWI: 43 ± 69,9cm3
p=0.00139
p=0.00028 (Fisher exact test)
In our research*
(*) Nguyen Duy Trinh, Pham Minh Thong 2014
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
37

38. 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
38

39. 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
39

40. 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
40

41. TICI = 3
41

42. mRS = 1
Before
After
42

43. Case 1b
- Woman 75yo, 1st hour
- M1 occlusion, large
penumbra
- Good recanalization
- mRS~1pt after 3 months
43

44. 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
44

45. 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
45

46. 46

47. 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

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

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

50. Evaluation scale
Điểm Đánh giá (khi so sánh với bán cầu bên bệnh với bên lành)
0 Không quan sát thất bất kỳ nhánh mạch máu nào đi vào vùng nhồi máu tại
bất kỳ phase nào
1 Có một vài nhánh mạch máu nhỏ đi vào vùng nhồi máu tại bất kỳ phase nào
2 Chậm 2 phase hiện hình mạch máu vùng ngoại vi VÀ giảm đậm độ-tốc độ
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 số lượng mạch máu trong vùng nhồi máu giảm
4 Chậm 1 phase hiện hình mạch máu vùng ngoại vi, nhưng đậm độ và tốc độ
ngấm thuốc thì tương tự
5 Không có chậm phase, quan sát thấy ngay các nhánh mạch máu bàng hệ đi
vào bình thường hoặc nhiều hơn trong vùng nhồi máu
• 0-3: nghèo bàng hệ (poor)̣, 4: vừa (moderate), 5: tốt (good) 50

51. 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)
51

52. 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)
52

53. • Menon et al., (2015). Neuroradiology, 000 (0).
Multi >< Single Phase
53

54. 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
54

55. ESCAPE
55

56. 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% 56

57. 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

58. 58

59. • 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
59

60. PHASE 1 PHASE 2 PHASE 3
• Multiphase score ~ 4 point (good collateral)
Multiphase
60

61. TTP
(Time to Peak)
CBF
(Cerebral Blood Flow)
CBV
(Cerebral Blood Volume)
• Mismatch > 35%
Perfusion
61

62. DSA (19h50’ – 20h10’)
• Solitaire 6/20: 1 times
• TICI 3 62

63. Follow up
• G ~ 15pt
• NIHSS ~ 6pt
• mRS ~ 2 after 2 days
63

64. 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

65. PHASE 1 PHASE 2 PHASE 3
Multiphase
• Multiphase score ~ 2 point (poor collateral)
65

66. DSA (15h15’ – 15h57’)
• Solitaire 6/30: 4 times
• TICI 3 66

67. MRI follow up
• G 15pt
• NIHSS ~ 9pt
• mRS ~ 4 after 2 wks
67

68. 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
68

69. THANK YOU FOR YOUR ATTENTION!