Update on Imaging, thrombolysis and stenting in Stroke

Question 1

What is the background for stroke?

Answer 1

11% of all deaths in England and Wales

500,000 dependent for ADLs

Question 2

What has changed in the last 6 years for acute stroke care?

Answer 2

• RCP audit highlights shortcomings for UK stroke care
• Thrombolysis rate gradually improving vs up to 1-% in continental Europe
• National Stroke Strategy published
• NICE guidelines on Stroke
• Stroke moved up the DOH agenda in England
• Stroke Networks formed
• Hyperacute stroke units set up
• Thrombectomy becoming standard of care

Question 3

Brain imaging should be performed immediately for people with acute stroke if any of the following apply:

Answer 3

• Indication for thrombolysis or early anticoagulation treatment
• On anticoagulant treatment
• Known bleeding tendency
• Depressed level of consciousness, GCS < 13
• Unexplained progressive or fluctuating symptoms
• Papilloedema, Neck stiffness or fever
• Severe headache at an onset of stroke’s symptoms

Question 4

What should be done for people with acute stroke without indication for immediate brain imaging scanning?

Answer 4

should be performed within 1 hour of arrival in hospital

Question 5

What do we need know from acute CT scan in a patient with a clinical diagnosis of acute stroke:

Answer 5

• Is the scan normal? i.e. can we start Thrombolysis refer for thrombectomy
• Confirm diagnosis of acute stroke and size
• Exclude haemorrhage
• Exclude stroke mimic

Question 6

What happens if CTA is available?

Answer 6

• Looks at all the blood vessels
• If you have a stroke 20% of patients will have disease of the carotid artery that needs treatment with carotid endarterectomy (CEA)
• 10% of patients who are suitable for thrombectomy
• Exclude significant stenosis of the carotid and vertebral arteries and any intracranial stenosis
• Enables fast tract to endarterectomy or discharge from a HASU to SU

Question 7

What should patients with suspected TIA undergo?

Answer 7

diffusion weighted MRI except where contraindicated

Question 8

TIA at MRI superior to CT

Answer 8

pick up small diffusion abnormalities that may not be seen on a CT

Question 9

NASCET and ECST:

Answer 9

• Long term benefit of carotid endarterectomy compared with medical treatment
• If you have a stenosis greater than 70% - absolute risk reduction is pretty good
• Not good treating less than 50% stenosis
• Above 99%, the flow drops in the carotid

Question 10

When was benefit from surgery greatest in?

Answer 10

men, patients aged 75 years or older, and those randomised within 2 weeks after their last ischaemic event

Question 11

What does the benefit from endarterectomy depend on?

Answer 11

not only on the degree of carotid stenosis, but also on several other clinical characteristics such as delay to surgery after the presenting event

Question 12

What is readily availble on all A&e for acute stroke?

Answer 12

CT

Question 13

What are the features for CT?

Answer 13

• Acute haemorrhage, may show infarct
• CTA for vessels
• CTP for extent of perfusion defect, CBV predicts infarct volume (DWI)
• Convenient
• Very quick < 5 minutes scan time
• Some time on workstation; new packages coming
• CT easy in ill patients
• Radiation secondary importance of having acute stroke

Question 14

What are the features for MRI?

Answer 14

• Sequences to detect lesion and blood
• Gradient echo (T2*) greater than CT (microbleed)
• DWI >CT
• MRA
• Perfusion – whole head
• Longer scan time, less post processing
• Access
• New sequences
• Will become easier to use in the future

Question 15

What is the Alberta Stroke Program Early CT score ‘‘ASPECTS’’?

Answer 15

10-point quantitative topographic CT scan score used in patients with middle cerebral artery stroke

Question 16

What has the ASPECT score been adapted for?

Answer 16

Posterior circulation

Question 17

What do we see in CT for acute stroke?

Answer 17

1. Thrombus in the vessels
2. Altered tissue perfusion
3. Cytotoxic oedema
4. Vasogenic oedema

Question 18

Where to look in CT in Acute Stroke?

Answer 18

• Vessels
• Grey: white differentiation
• Basal ganglia/capsules
• Insular ‘’ribbon’’
• Cortex
• Swelling: sulci effaced

Question 19

What can easily be seen on the CT, and picked up quicker than MRI?

Answer 19

Haemorrhage

Question 20

What can’t MRI be used as ?

Answer 20

Single sequence investigation (‘‘turbo charged CT’’)

Question 21

What must haemorrhage include?

Answer 21

Blood sensitive sequence

• GRE or parenchyma
• FLAIR for SAH

Question 22

What should not be used alone for acute stroke imaging?

Answer 22

DWI

Question 23

What is Low Grade Glioma and what to look for?

Answer 23

1. Can be peripheral, wedge shaped and non-enhancing
2. Look for:
   - Age and History
   - Density, swelling but non-enhancing
   - DWI characteristics and age of lesion

Question 24

What is the most common cause of stroke for pregnant ladies?

Answer 24

Venous thrombus

Question 25

Where is Core observed in?

Answer 25

diffusion, reduction in blood volume and an increase in MTT [mean transient time] • Due to block of middle cerebral artery

Question 26

What is the aim of thrombolysis?

Answer 26

reperfuse penumbra before it infarcts

Question 27

What is TIA?

Answer 27

Like a stroke without core infarct in eloquent area - Milder perfusion deficit - Often has DWI lesion

Question 28

What does ASPECT aid?

Answer 28

Methodical image analysis and prognosticatio

Question 29

What is not very dark ?

Answer 29

Infarct less than 24 hours

Question 30

What do infarcts not usually present with?

Answer 30

Fits | Especially in young people

Question 31

What must be included if using MRI for acute stroke?

Answer 31

Gradient echo imaging

Question 32

What are a few tips for looking at scans?

Answer 32

1. Ambient lighting, monitor quality etc 2. Hang as well as scroll 3. Correct window/centring 4. Provide/obtain clinical info 5. Think about anatomy (speech not always left dominant) 6. Eye deviation

Question 33

What should be compared with initial scan?

Answer 33

Routinely obtain post thrombolysis follow up imaging

Question 34

What are the objectives of I.V. Thrombolysis?

Answer 34

1. To improve clinical outcome at 3 month - Proportion of patients without handicap (mRS 0-1) - Proportion of patients without dependency (mRS 0-2)

Question 35

What are the Modified Rankin scale?

Answer 35

``` 0 - no symptoms 1- No significant disability despite symptoms 2- Slight disability 3- Moderate disability 4- Moderately severe disability 5- Severe disability 6- Dead ```

Question 36

What cannot be the objectives of I.V. thrombolysis?

Answer 36

- To reduce mortality only - To reduce handicap only - To improve recanalization only [return of blood flow to a venous segment that had previously been occluded]

Question 37

Meta-analysis of trials

Answer 37

NNT to prevenet 1 death or dependency (mRS 2-6) - <90 minutes: 2 - 90-180 minutes: 7 - 180-270 minutes: 14

Question 38

For every 20 patients treated

Answer 38

- 1 extra will be cured (Rankin 0) | - 1 extra will do very well (Rankin 1)

Question 39

So, whom would you thrombolyse?

Answer 39

- Patient whom you think had a stroke - Within 4 ½ hours - Normal scan - No contraindications

Question 40

What are the contraindications of thrombolysis?

Answer 40

* Age under 18 or over 8- years * Very severe stroke * Prior stroke and concomitant diabetes * History of haemorrhagic diabetic retinopathy * Receiving oral anticoagulants e.g. warfarin * Blood pressure limits >185/110 * IV medication needed to reduce BP to these limits * Extensive infarction on CT

Question 41

What are the 5 trials for thrombectomy for acute ischaemic stroke?

Answer 41

- MR CLEAN - ESCAPE - EXTEND IA - SWIFT-PRIME - REVASCAT - THRACE

Question 42

Number needed to treat: 3-7

Answer 42

- Within 2-3 hours: 3 - Within 41/2 hours: 7 - PCI 35-45- to get benefit

Question 43

What can marked benefits be observed in?

Answer 43

Endovascular treatment

Question 44

What are the inclusion criteria for Throbectomy?

Answer 44

Achieved within 6 hours of onset of symptoms and where: - Inadequate response to IV thrombolysos by time of groin puncture - Patients unable to receive IV thrombolysis because recent surgery or on anticoagulants

Question 45

What is the challenge for Thrombectomy?

Answer 45

1. STAFF 2. CTA n DGH Local HASU 3. Drip and ship or mothership 4. Ambulance transfer HEMS 5. Repatriation

Question 46

What is the patient pathway?

Answer 46

1. Admission to nearest hospital with an hyperacute stroke unit 2. Undergo initial investigations - CT and CTA 3. Start treatment whee appropriate with IV tPA 4. Critical transfer to nearest thrombectomy centre