Stroke Brain imaging + ischaemic and haemorrhagic

Question 1

What are different types of CT to visualise brain in stroke?

Answer 1

Unenhanced CT scan
CT angiogram (CTA)
CT perfusion scan (CTP_
CT venogram (CTV)
Contrast enhanced brain scan (CECT) for blood brain barrier disruption

Question 2

What landmark should you look for to work out where in brain you are, which lobes etc?

Answer 2

Look for central sulcus - makes curve like greek letter omega
- anterior to this is frontal
- posterior to this is parietal

Question 3

CT cut through basal ganglia - identify brain structures

Answer 3

Question 4

A CT axial cut through sylvan fissure, identify Sylvian fissure and what lives there (v relevant for stroke!)

Answer 4

MCA lives in Sylvian fissure - in this image it is isodense (similar to surrounding brain tissue) so hard to see

When it is hyperdense (bright white) we have problems like stroke!

Question 5

This is CT cut of midbrain - identify:

midbrain
basal cistern
Uncus (can herniate)
Lateral horn of the lateral ventricle (hydrocephalus -dilated)

Answer 5

Question 6

CT cut to pontine level
identify:

Pons
Cerebello- pointine angle
4th ventricle

Answer 6

Question 7

CT axial cut at the medulla - identify
medulla
4th ventricle
cerebellum

Answer 7

Question 8

What are the two types of stroke?

Answer 8

Question 9

Ischaemia vs infarction in stroke:

Answer 9

Ischaemia: insufficient blood flow to meet metabolic demand. Poor 02, cerebral hypoxia.
REVERSIBLE
but it can lead to ——> infarction

Infarction: cell and brain tissue death
IRREVERSIBLE

Question 10

Describe the pathophysiology of how Ischaemia leads to infarction

Answer 10

Question 11

What is a TIA?

Answer 11

“Brief episode of neurological dysfunction caused by focal brain and/or retinal ischeaemia, with clinical symptoms lasting <1hr and without evidence of acute infarction”

Question 12

What are the four ages of an infarct (timings and how classed)

Answer 12

Hyperacute: <6 hours

Acute: < 7 days

Subacute : < 4 months

Chronic : >4 months

Question 13

How do you treat a hyperacute infarct?

Answer 13

IV thrombolysis w/ Alteplase
window of 4.5 hours

Question 14

Why does a suspected stroke need to be imaged?

Answer 14

1. Thrombolysis (for hyperacute infarct) can only be given if excluded haemorrhage - need imaging
2. Patients with stroke mimic e..g tumour - should NOT get thrombolysis - need to image
3. BUT stroke is a clinical diagnosis might not need hyperacute infarct on imaging to prescribe thrombolysis

Question 15

What are the benefits of CT scanning in stroke

Answer 15

1. available 24/7
2. Quicker than MRI
3. Fewer contraindications / intolerances and need for MRI compatible resuscitation equipment

Question 16

What is primary technique for stroke imaging and how does it aid clinicians in their decision making?

Answer 16

Unenhanced CT

-done ASAP post stroke

• highly sensitive in detecting acute haemorrhage
• sensitive to detect stroke mimics e.g tumour, arterial venous malformation (AVM) and to determine further investigations
• may show the target thrombosed vessel
• identify infarctions that are too big, or old for thrombolysis (due to increased risk of haemorrhage)

Question 17

What appears hyperdense on CT?

Answer 17

Hyperdense = WHITE BRIGHT
mineralised structures: e.g. Ca bone or calcified lesions
Blood

Question 18

What appears as hypodense on CT?

Answer 18

Hypodense = dark
Fluid appears dark on CT

so usually due to:
chronic lesions
Fluids
cysts
oedema

Question 19

Unenhanced CT pf a cerebral infarct
What signs do you see?

Answer 19

Hypoattenuating
Cortical-sub cortical
within a vascular territory

Question 20

Images demonstrate the territories of ACA, Middle cerebral artery MCA and posterior cerebral artery on CT and drawing - try and visualise

Answer 20

Question 21

Describe the early signs of infarction pictured here

Answer 21

• Hypoattenuation Right side
  -Sulcal effacement in right MCA territory
  -RIGHT Middle cerebral artery infarct

Question 22

Describe early signs of infarction pictured here

Answer 22

• Loss of gray matter - white matter differentiation of the left basal ganglia
• sulcal effacement in the left MCA territory

Question 23

Describe early signs of infarction pictured here

Answer 23

-Hyperattenuating left MCA
-Intra -arterial thrombus (30% of cases)
- False positives: Calcifications, dolichoectasia, polyscythaemia, increased haematocrit

Question 24

What are the causes of acute infarction due to cerebral ischaemia?

Answer 24

Embolism (most common)
e..g cardiac/ carotid / paradoxical / aorta

Thrombosis e.g. arteriosclerotic disease

Arterial dissection

Question 25

The role of MRI in stroke imaging

Answer 25

MRI is more sensitive in detection and diagnosis of acute infarction - diffusion weighted imaging - positive from 2 hours - 3 weeks Good to use if: Previous CVD makes CT difficult Difficult location for CT - e.g. posterior fossa Equivocal case - ? tumour sensitivity - TIA clinic

Question 26

Hyperacute findings of acute infarction on CT when might you be able to visualise a clot?

Answer 26

see hyperdense artery (clot w/in lumen of artery) clot = hyperdense compared to flowing blood gets more hyperdense with time - often see immediately on CT as the thrombo- embolism has often travelled from somewhere else in body

Question 27

Hyperacute findings of acute infarction on CT when might you be able to visualise early parenchymal signs ?

Answer 27

hypoattenuation

Question 28

Where is the thromboembolsim in these 2 unenhanced CTs? How would you confirm visualisation of the clot?

Answer 28

LEFT image: Right MCA = hyperdense RIGHT image: Hyperdense seen in top of basilar artery Confirm with: CT angiography Result: the hyperdense area seen on non-contrast CT imaging will become a filling defect on CT angiography

Question 29

What does this unhenanced CT show?

Answer 29

Chronic Right MCA stroke hypo-dense = chronic lesions well defined, wedge shaped, same density as CSF and conforms to vascular territory

Question 30

What does this unenhanced CT scan show?

Answer 30

Acute right MCA infarction see hypodensity in MCA territory From scan 8 hours post symptom onset (acutely ischaemic neurons swell, but oedema takes 6-8 hours to show on CT. this scan taken later - we can see. Early CT scans of ischaemic stroke can often look falsely normal!)

Question 31

What does this show?

Answer 31

This is (left to right) Unenhanced CT MRI CT angiography of ACUTE RIGHT MCA infarction

Question 32

What is Alteplase licensed for?

Answer 32

- licensed to first 4.5 hours post stroke -This leads to current preferred model of 'clinical prescribing' of Alteplase: limits use of CT to eliminate haemorrhage and stroke mimics

Question 33

How does a perfusion CT of brain work?

Answer 33

- use iodinated CT contrast - repeated images of the same few levels of brain tissue are taken during the first pass of the contrast through the brain - the transient hyperattenuation is proportional to the amount of contrast in the vessels of that region

Question 34

What are the parameters used in CT Perfusion

Answer 34

MTT : Mean transit time CBV : cerebral blood volume from this can work out CBF : cerebral blood flow CBF= CBV/MTT These parameters are displayed as visual maps to be analysed

Question 35

Answer 35

RIGHT = ischaemic penumbra The ischaemic penumbra surrounds the infarct core - increased MTT/Tmax - moderately reduced CBF - near-normal or increased CBV(due to autoregulatory vasodilatation) https://radiopaedia.org/articles/ct-perfusion-in-ischaemic-stroke

Question 36

Answer 36

The infarct core is the part of the ischaemic brain which has already infarcted or is destined to infarct regardless of therapy. - increased MTT - markedly decreased CBF - markedly decreased CBV Can overestimate infarct core if use Note, that if one uses CBF alone to visually assess core size, it is easy to overestimate infarct core, as the penumbra often has reduced CBF also. So, even though some automated processes used CBF to define the core, CBV is a safer parameter if 'eye-balling' the scan. https://radiopaedia.org/articles/ct-perfusion-in-ischaemic-stroke

Question 37

What is the relevance of identifying 1. the infarct core 2. the ischaemic penumbra in acute ischaemic stroke on CT perfusion studies?

Answer 37

a patient with a small core and a large penumbra is most likely to benefit from reperfusion therapies.

Question 38

How do CT perfusion maps help work out what is salvageable brain tissue?

Answer 38

Question 39

What does this show?

Answer 39

Brain stem infarction in a 43yr old woman admitted unconscious - Large potine infarct - Hyperattenuating basilar artery Brainstem infarcts: -Slower to appear -Slower to evolve - Longer theraputic window

Question 40

Spontaneous Intracranial haemorrhage (ICH): 1. % of strokes 2. Clinical clues an ICH

Answer 40

1. 15% of strokes 2. Clincial clues: - possible underlying causes - reduced level of consciousness at admission - Hx of headache - seizures

Question 41

Intracranial haemorrhage can be 1. Primary (small vessel) haemorrhage 2. Secondary haemorrhage What are some causes of 1...?

Answer 41

- Hypertension - Cerebral amyloid angiopathy (CAA)

Question 42

Intracranial haemorrhage can be 1. Primary (small vessel) haemorrhage 2. Secondary haemorrhage What are some causes of 2./.?

Answer 42

- Haemorrhagic transformation infarct - venous sinus thrombosis infarct and venous infarct - Tumour - GBM, anaplastic astrocytoma, mets - Vascular - aneurysm, AV<. vasculitis -Coagulopathy - warfarin, aspirin - Cocaine / alcohol

Question 43

Outline what can happen in the brain during an intracranial haemorrhage?

Answer 43

Question 44

What are some factors of intracranial haemorrhage that predict outcomes? e.g. early mortality, poor outcomes, clinical

Answer 44

Question 45

Intracranial haemorrhages can be located where in the brain?

Answer 45

Question 46

What imaging can you use to diagnose Intracranial haemorrhage?

Answer 46

CT first then MRI

Question 47

Outline how CT is used in the diagnosis of intracranial haemorrhage?

Answer 47

-Acute bleed and immediate complications of acute bleed - time course - uderlying cause - CTA, CTV, CEET

Question 48

How is MRI used in the diagnosis of intracranial haemorrhage ?

Answer 48

Question 49

How is Intracranial haemorrhage managed ?

Answer 49

Neurosurgery: - clot reduction, decompression craniotomy (mandated in cerebellar haemorrhage with GCS <14 and haematoma >40mls) -Intraventricular shunting (mandated in hydorcephalus) Medical: -Suportive - Blood pressure - Mass effect - seizures - secondary prevention

Question 50

How does an acute haemorrhage look on CT?

Answer 50

- Large globulin molecule of blood stops attenuating X-rays - so high density - hyperattenuating - Lesion density depends on age of haematoma. As globulin is broken down density will fall until dark protein fluid (like CSF) is left small bleeds - disappear in a week large - take months

Question 51

How do you class the stages on CT of an acute haematoma?

Answer 51

Question 52

What does this show

Answer 52

Typical hypertensive bleed in Basal ganglia - 2/3rd putamen - 1/4 thalamas

Question 53

What does this show?

Answer 53

Bleed due to Cerebral Amyloid Angiopathy (a condition in which proteins called amyloid [amyloid-beta (Aβ)] build up on the walls of the arteries in the brain. CAA causes bleeding into the brain (hemorrhagic stroke) and dementia.

Question 54

Intratumoral Haemorrhage......what are some clues / action / Primary malignancy it could be?

Answer 54

Clues: -History - stutering onset - Oedema - Irregular nature of the clot Action: ASAP CE-MRI (contrast enhanced) Primary malignancy: Glioblastoma multiforme / anaplastic astrocytoma Mets: Lung, renal, melanoma, choriocarcinoma, thyroid

Question 55

Arteiovenous malformation haemorrhage .what are some...clues....action ?

Answer 55

Clues: - age -abnormal vessels Action: - CTA / CTV or MRA / MRV - urgent neurosurgical referral as may be further bleeding - DSA and endovascular treatment

Question 56

What is this? What could it be caused by?

Answer 56

Question 57

What are some complications of Intracranial Haemorrhage ?

Answer 57

MASS EFFECT : - effacement of ventricles - Displacement of ventricles - Midline shift - Twisted ventricle - Hydrocephalus - Cerebral herniation (subfalcine, uncal, tenting, coning) - Raised ICP

Question 58

Mass effect and midline shift in intracerebral haemorrhage ( lots of detail but think seeing images helpful to get an idea of what looks like)

Answer 58

Question 59

What complication of intracerebral haemorrhage does this depict?

Answer 59

Question 60

What complications of intracerebral haemorrhage does this depict?

Answer 60

Question 61

What complications of intracerebral haemorrhage does this depict?

Answer 61

Question 62

What does this depict?

Answer 62

Cerebellar haemorrhage on unenhanced CT

Question 63

Explain what makes up cerebral perfusion?

Answer 63

Question 64

What is an elevated ICP?

Answer 64

e.g with mass lesion / mass effect Elevated = >20 mmHg

Question 65

For intracranial pressure monitoring what BP / ICP and CCP (cerebral perfusion pressure) is ideal / aim for?

Answer 65

Rule of thumb: - BP less than 130 mm Hg (to reduce bleeding) but above 90 to maintain CPP -ICP less than 20 mm Hg - Ensure CPP is >70 mm Hg (if below brain will usffer iscahemic injury)

Question 66

Outline the membranes that surround the brain

Answer 66

Question 67

Diagnosis? Presentation? Pathophysiology?

Answer 67

Diagnosis: - Extradural / epdiural haematoma - Bi- convex (lemon shape) as blood spread is limited by sutures of brain, appears hyperdense Presentation: - Young men - trauma - 90% have skull fracture - examine for closely - LOC, consciousness, LOC (lucid intervals) Pathophysiology: - Blood collects between periosteum of blood inner table of bone and inner layer of dura - often middle meningeal artery

Question 68

Diagnosis ? Presentation ? Pathophysiology?

Answer 68

Diagnosis: - Actue (L) and chronic (R) subdural haemorrhage - concave, cross suture lines, hyperdense Presentation: - elderly - trauma Pathophysiology: - Blood collection between arachnoid and dura - Torn bridging veins - brain atrophy

Question 69

Diagnosis ? Presentation?

Answer 69

Diagnosis: Subarachnoid haemorrhage Presentation: - older pt - HTN - smoker - thunderclap headache - nausea and vomiting - LOC Pathophysiology: - arteriovenous malformations - berry aneurysm

Question 70

Is MRI helpful in Intracerebral haemorrhage?

Answer 70

Not practical in hyperacute / acute pt as the first way to diagnose a pt. Acute bleed - CT MRI good for: - Identifying underlying causes - Great at ageing bleeds to see if subacute / chronic - seeing haemorrhage transformation of an infarct (diffusion weighted imaging)

Question 71

How do Saccular aneurysms (berry aneurysms) develop?

Answer 71

- Aneurysms develop due to pressures on the arterial wall (vessels in subarachnoid space) - Usually at bifurcation points - Large cerebral arteries in anterior circle of Willis most affected - Intracranial arteries lack external elastic lamina and have thin adventitia - Small aneurysms(<5mm) unlikely to rupture Risk factors for developing aneurysms (not conclusive) Same as cardiovascular- hypertension, smoking etc Alcohol++, APDK

Question 72

investigations for suspected subarachnoid haemorrhage?

Answer 72

Imaging: - 1st line- CT scan (catch 93% w/in 24 hrs of bleed) Other: - lumbar puncture (hx suggests but CT negative) wait 6 hours (12+ is preferable)- for lysis of RBC (Xanthochromia) CSF: high protein, WCC not raised, glucose normal Once diagnosis confirmed: - Angiography is performed to confirm location of aneurysm

Question 73

Management of subarachnoid haemorrhage?

Answer 73

- A- E - airway support? - cardiovascular monitoring - CCB e.g. Nimodipine (to prevent vasospasm and secondary ischaemia) Surgery: - pts w/ good neurological status within 72 hours -to prevent re-bleeding - Clipping (surgeons) clamp neck of aneurysm (with spring clip) - Coiling (neuro-radiologists) insertion of wire into aneurysm sac which causes thrombosis of blood within aneurysm

Question 74

Appearance of blood on MRI in T1 vs T2 over time Acute, subacute, chronic (taken image from a youtube tutorial link included, quicker way than the PP which was very long and convoluted)

Answer 74

https://www.youtube.com/watch?v=DdPRfPm9SI4&t=3043s