Neurovascular - stroke

Question 1

what is a stroke

Answer 1

a sudden interruption of continuous blood flow to the brain

Question 2

types of stroke

Answer 2

Ischaemic (87%)
Haemorrhagic (13%)

Question 3

How is an ischaemic stroke treated

Answer 3

Thrombolysis with antiphase within 4.5 hrs of onset of symptoms

Thrombectomy is considered when: Large vessel occlusion is confirmed on CTA/MRA within 6 hrs or between 6-24 hours ONLY IF
potential to salvage brain tissue (shown on CT perfusion or DWI MRI showing
limited infarct core

Question 4

The role of imaging in stroke

Answer 4

demonstrates early signs of ischaemia

• Exclude intracranial haemorrhage
• excludes stroke mimics e.g tumour
• aids selection of treatment

Question 5

NICE guidelines for early assessment of those with suspected acute stroke

Answer 5

NICE guidelines stroke and TIA in 16+: diagnosis and initial management

Question 6

What do the guidelines recommend for Suspected acute stroke

Answer 6

NG128 recommends immediate* non-enhanced CT head if there are:

• indications for thrombectomy or thrombolysis
• a known bleeding
  tendency
• GCS below 13
• severe headache at onset of stroke symptoms

-on anticoagulant medication

Question 7

strengths of Non-contrast enhanced CT

Answer 7

Non-contrast – so bleeds can be seen reliably

• it is practical, as CT is readily available, quick

Windowing, algorithms – ability to review blood, brain, bone from one data set

Can go on to do other imaging CT angiography and perfusion if required

CT can reliably demonstrate bleeds so will be able to diagnose or r/o haemorrhagic stroke or other stroke
mimics

can easily monitor pt during scan

Question 8

weaknesses of Non-contrast enhanced CT

Answer 8

High radiation dose

Question 9

the role of CT angiography

Answer 9

aids selection of therapy - shows site of any occlusions, stenosis and thrombus so can direct
therapy – large vessel occlusion may require thrombectomy

Question 10

strengths of CT angiography

Answer 10

has high resolution - shows arch of aorta-COW

Thrombus will show as filling defect

it practical and accessible and can be done immediately after CT head

non-invasive

Question 11

CT angiography weakness

Answer 11

requires contrast

high radiation dose

Question 12

CT angiography indications

Answer 12

thrombectomy may be indicated (up to 24 hours post onset of
symptoms if large vessel occlusion suspected

Question 13

Role of CT perfusion

Answer 13

aids the selection of therapy

Differentiates between salvageable brain tissue (penumbra) and infarcted
brain (infarct core

contrast injected over time and scanned repeatedly to look at
regional blood flow

Question 14

indications for CT perfusion

Answer 14

if thrombectomy being considered between 6-24 hours (and large
vessel occlusion shown on CTA); or if uncertainty of significance of stenosis

Question 15

MTT ( CT perfusion)

Answer 15

mean transit time

Question 16

CBV ( CT perfusion)

Answer 16

cerebral blood volume

Question 17

infarcted brain (infarct core) has

Answer 17

increased MTT and reduced CBV

Question 18

salvageable tissue (penumbra) has

Answer 18

increased MTT but normal CBV

Question 19

limitations to CT perfusion

Answer 19

high radiation dose and requires contrast

Question 20

role of angiography

Answer 20

interventional procedure

Question 21

strengths of angiography

Answer 21

direct therapy

high spatial and temporal resolution

directs mechanical thrombectomy

Question 22

weaknesses of angiography

Answer 22

high radiation dose

invasive

iodinated contrast risks

Question 23

why does mri have a limited role

Answer 23

• time consuming, accessabillity and availability

Question 24

2 key sequences in MRI

Answer 24

Diffusion weighted imaging (DWI)

Blood sensitive sequences

Question 25

Diffusion weighted imaging (DWI)

Answer 25

very sensitive to detection of early and small infarcts

Question 26

Blood sensitive sequences

Answer 26

Gradient echo or Susceptibility weighted imaging SWI – sensitive to bleeds –
blooming artefact

Question 27

if CT and/or
iodinated contrast is contraindicated…

Answer 27

MRI angiography and MR perfusion can be performed with or without gadolinium

Question 28

TIA

Answer 28

“mini stroke” is caused by a temporary disruption in the blood supply to part of the brain.

Question 29

TIA treatment

Answer 29

Carotid endarterectomy – surgical removal of atherosclerotic plaque

Question 30

imaging for people with suspected TIA

Answer 30

do not offer CT unless there is clinical suspicion of an alternative diagnosis CT can detect

consider MRI (including diffusion-weighted and blood-
sensitive sequences) to determine the territory of
ischaemia, or alternative pathologies

Question 31

role of MRI in suspected TIA

Answer 31

To rule out other causes of the symptoms:

Question 32

for TIA DWI shows

Answer 32

non disabling stroke (shown as high signal)

Question 33

for tia Blood sensitive sequences show

Answer 33

cerebral amyloid angiopathy as blooming artefact

Question 34

How are the carotid arteries imaged

Answer 34

Duplex ultrasound
CTA
MRA
DSA

Question 35

Duplex ultrasound

Answer 35

Preferred choice for screening. But only shows small sectional view of
artery.

Question 36

CTA

Answer 36

non invasive, but IR & iodinated contrast but excellent spatial
resolution and 3D data

Question 37

MRA

Answer 37

Non invasive, can be performed with or without gadolinium(TOF); but
MRI contraindications and time consuming

Question 38

DSA

Answer 38

Invasive, but excellent spatial and temporal resolution (gold standard).
Not usually used for TIA though as increased risk of stroke