Brain imaging

Question 1

What are the common imaging techniques for the brain

Answer 1

CT and MRI

Question 2

Advantages of CT

Answer 2

quick, accurate, well tolerated, can enhance with contrast

good bone definition

Question 3

Disadvantages of CT

Answer 3

radiation exposure therefore contraindicated in some eg young, pregnant
Contrast - renal impairment, hypersenstivity

Question 4

Advantages of MRI

Answer 4

no radiation
excellent soft tissue imaging
can use contrast
many sequence patterns

Question 5

Disadvantages of MRI

Answer 5

takes much longer
Claustrophobia
contraindicated in those with pacemakers/implants

Question 6

On a CT scan, bone+blood appear black
fluid and air appear white
True or false

Answer 6

FALSE
Bone+blood = white
Air+fluid = black

Question 7

What shape is the midbrain on a CT scan

Answer 7

Mickey mouse ears

Question 8

What are the name of the fine gyri on the cerebellum

Answer 8

Folia

Question 9

How does fluid appear on a MRI T1 sequence

Answer 9

Dark - better for seeing anatomy

Question 10

How does fluid appear on a MRI T2 sequence

Answer 10

White - better for spotting pathology

Question 11

Causes of ischaemic stroke

Answer 11

Embolism - cardio, paradoxical, fat, air
Atherosclerosis
Thrombosis
arterial dissection

Question 12

What are the vascular territories of the brain

Answer 12

ACA, MCA and PCA

Question 13

Reasons for imaging in stroke

Answer 13

Confirm infarct
Exclude haemorrhage
Rule out stroke mimics
Allow for rapid treatment

Question 14

Examples of stroke mimics

Answer 14

Todd’s paresis (post-ictal)

tumour

Question 15

1st line imaging in stroke

Answer 15

CT scan without contrast

Question 16

Earliest characteristic sign on CT in an ischaemic stroke

Answer 16

Hyperdense vessel sign - thrombus in occluded vessel appears bright white
Most commonly in MCA

Question 17

Imaging features of ischaemic stroke

Answer 17

hyperdense sign 
loss of grey-white matter interface 
cortical hypodensity 
parenchymal swelling and gyral effacement 
loss of insular ribbon (cortex)
significant mass effect

Question 18

normal calcified structures in the brain

Answer 18

pineal gland
choroid plexus
basal ganglia
falx

Question 19

Describe imaging features in extradural haemorrhage

Answer 19

Biconvex shape

rupture of middle meningeal artery

Question 20

Features of subdural haemorrhage

Answer 20

crescent shape (can be very subtle)
acute/chronic
rupture of bridging veins

Question 21

Features of subarachnoid haemorrhage

Answer 21

White star sign
white (blood) in suprasellar cistern
sylvian fissures
sulci

Question 22

What other investigation is done in SAH

Answer 22

cerebral angiography

Question 23

Features of brain metastases

Answer 23

multiple
most common brain tumour in adults
contrast ring enhancing
LOTS of oedema and mass effect

Question 24

Features of primary brain tumours

Answer 24

usually single
more common in children
degree of oedema depends on grade of tumour

Question 25

What is 1st choice imaging in cauda equina syndrome

Answer 25

MRI