Imaging of CNS

Question 1

Describe the utility of plain film/X-ray for imaging the brain?

Answer 1

Not very useful, as brain is water density and doesnt show up on X-ray

Can be utilised for skull fractures

Question 2

Describe the process and utility of pneumoencephalography for imaging the brain?

Answer 2

Take out CSF > replace with air > rotate patient

Outlines ventricles > can see brain due to relative difference in density

No longer used

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Question 3

How is catheter angiography used to image the brain?

Answer 3

Catheter access through groin > navigate into head and neck vessels > inject contrast medium

Digitally subtract images to get outline of brain vessels

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Question 4

Describe the utility of ultrasound for imaging the brain?

Answer 4

Bone blocks US waves - otherwise would be perfect

Mainly used in neonates, as fontanels act as an acoustic window

Can use Doppler US in adults to measure flow in cerebral arteries

Question 5

Describe the difference between T1 and T2 weighted MRI?

Answer 5

T1 - fat and fluid black

T2 - fat and fluid white

Question 6

Which types of information can MRI provide about the brain?

Answer 6

Anatomical and functional

Question 7

What is the most common use of fMRI?

Answer 7

Detect which side language is on before surgery/tumour resection

Question 8

Why can PET and SPECT be used to measure?

Answer 8

Metabolic activity of the brain

Can be used to see hypermeatbolic degenerative conditions or seizures during epilepsy

Question 9

Why can’t PET and SPECT be used for functional imaging?

Answer 9

Poor temporal resolution

Question 10

Why is a relatively noisy image of the brain produced in CT?

Answer 10

Grey and white matter have similar density

Need narrow window to distinguish them

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Question 11

Which imaging modality best distinguishes grey and white matter in the cortex?

Answer 11

MRI, in particular T1 weighted

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Question 12

What are T1 weighted MRI images utilised for?

Answer 12

Anatomical distinctions between cortex and adjacent white matter

Question 13

What are T2 weighted MRI images utlised for?

Answer 13

Outlining areas of abnormal physiology

Identify areas with abnormal content

Question 14

What is the most common cause of TLE?

Answer 14

Hippocampal sclerosis

Challenging to image

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Question 15

Which cranial nerves can be seen on MRI?

Answer 15

All of them

Question 16

Why is CN V often imaged?

Answer 16

Trigeminal neuralgia

Question 17

Which imaging modalities can be used to image intracranial arteries?

Answer 17

Digital subtraction angiography

CT angiography

MR angiography

Transcranial US

Question 18

Is the vasculature opf the brain constant across individuals?

Answer 18

Large vessels are very constant on location

A lot of variations in smaller vessels and Circle of Willis anatomy

Question 19

How does thromboembolic stroke appear on imaging?

Answer 19

Hyperdense

Question 20

How does arterial dissection appear in imaging?

Answer 20

Rat tail appearance

Question 21

What are watershed strokes?

Answer 21

Strokes that occure between vascular territories, typically due to hypoperfusion

Question 22

How can intracranial veins and dural sinuses be imaged?

Answer 22

Digital subtraction angiography

CT venography

MR venography

Question 23

Are the cerebral veins constant in their location across individuals?

Answer 23

Same as arteries; large veins are constant, but there is a lot of variation across smaller veins