1. Dr Kneale Metcalf Stroke Physician (NNUHFT)
Stroke Imaging
Dr Kneale Metcalf
Stroke Physician (NNUHFT)

2. Overview Modalities available When to use? Targets Real world imaging
Future aspirations

3. Hyperacute Stroke Diagnosis difficulties Patient stability issues
Vomiting
Airway
Low GCS
Seizures

4. CT Scan First time every time Fast Safe Available
?? Posterior, late presentation
Fast
Safe
? Radiation
Available

5. CT Scanner

6. Early CT scan Give Radiologist correct information
TIME of onset neurology
Side and details of neurology
Associated headache?
Trauma?
Anticoagulant?
Relevant PMH
Cancer
Stroke
Neurosurgery / clips etc.

7. Early CT scan Often normal Why do? Exclude haemorrhage Exclude tumour
Grade for thrombolysis risk

10. Dense Middle Cerebral Artery

12. Do early infarct signs matter?
Help confirm diagnosis
Dense middle cerebral artery
10% chance opening with IV thromolysis
? May lead to intra-arterial or mechanical treatments
Prognosis for thrombolysis
1/3 MCA territory

13. ASPECTS Canadian study Academic CT head interpretation
Leads to 10 point scoring system on plain axial CT head
Scores of <7 increased functional dependence + increased risk of death

14. ASPECTS Scored from two axial slices 10 points
One at thalamic level / basal ganglia
One just above ganglionic structures (such that none are seen)
10 points
One subtracted for each area of early ischemic change (thus score 10=normal scan)

16. Core message
Extensive early infarction may be poor prognostic indicator for outcome from thrombolysis

17. Intracerebral Haemorrhage
Main causes
Hypertension
Cerebral Amyloid Angiopathy (CAA)
Rarities

20. Hypertensive bleed

21. Cerebral Amyloid Angiopathy

22. Can be more subtle

23. Core message
Main causes of intracerebral haemorrhage are amyloid angiopathy and hypertension

24. Tumour Can be subtle History review Plain CT may not show
Non acute onset
Seizures
Headache
Cancer
Plain CT may not show
Contrast

25. Subtle sub-acute LEFT weakness

26. Post contrast

30. Brain tumours Often contrast enhance May have vasogenic oedema
May respect grey / white junction

31. Other mimics
Subdural haematoma
Sub arachnoid haemorrhage ++

32. Subdural haematoma

33. Sub arachnoid haemorrhage

34. Don’t miss mimics
History just as important as the scan!

35. Timing of CT changes

36. Infarct

38. Haemorrhage

39. Haemorrhage

40. Core message
After days both haemorrhage and infarct both look like a black hole
Important to be able to distinguish old from new infarcts

41. Urgent Scans
% of URGENT scans performed within 60mins of arrival to hospital (Best Prac + NICE quality standard)
90% by April 2011
Best practice = scan + report

42. What are indications for an urgent scan?
GCS <13
On Warfarin
Bleeding tendency
Severe headache
Papilloedema / neck stiff / fever
Progressive / fluctuating symptoms
For thrombolysis

43. MRI scan

44. Why do an MRI? If stroke uncertain To confirm vascular territory
Look for multi-territory involvement
Look for previous haemorrhage

45. Main MRI sequences Diffusion

46. Main MRI sequences Gradient-echo (T2*)

47. CT Perfusion
Concept of ischaemic pemumbra

48. CT Perfusion
Cerebral blood volume
Cerebral blood flow
Mismatch

49. CT Perfusion
Wake up strokes
Large strokes
Timing questions
Mimics

50. Future More CT Perfusion More MRI
Movement towards acute arterial imaging

51. Summary Brain imaging from Stroke Physician perspective
Targets – why + how
Where imaging may go