Radiology (CT head / MRI) interp.

Question 1

MRI - difference between T1 and T2 + which is more commonly used?

Answer 1

• T1 - ONE tissue is bright: fat
• T2 - TWO tissues are bright: fat and water

(T2 is more commonly used)

Question 2

What can you do with an MRI to see metastases and vasculature more clearly?

Answer 2

Add contrast (Gadolinium-enhanced)

Question 3

Answer 3

Question 4

Name the 3 planes

Answer 4

Question 5

Answer 5

Question 6

Answer 6

Question 7

Spot diagnosis + anatomy of where the blood is (layers) + usual cause

Answer 7

Extradural (or epidural) haemorrhage - lemon-shape of hyperdensity

• Collection of blood between the dura mater and skull
• Cause: usually trauma (look for skull fracture)

Question 8

Spot diagnosis + anatomy of where the blood is (layers) + usual cause

Answer 8

Subdural haemorrhage with midline shift - hyperdensity near edge of skull

• forms between dura mater and archnoid mater
• Cause: typically secondary to trauma

Question 9

Spot diagnosis + anatomy of where the blood is (layers)

Answer 9

Subarachnoid haemorrhage - spider pattern of hyperdensity within the cisterns

• involves bleeding into the subarachnoid space - between the arachnoid mater and pia mater
• Cause: usually trauma / sometimes ruptured aneurysm

Question 10

Spot diagnosis + 2 subtypes + cause

Answer 10

Intracerebral haemorrhage - bleeding within brain

• Can be intraparenchymal (within brain tissue) OR intraventricular (within ventricles)
• Cause: secondary to a ruptured blood vessel (eg. from hypertension)

Question 11

Spot diagnosis

Answer 11

Hyperdense MCA sign (thrombosis)

Question 12

Spot diagnosis

Answer 12

Hydrocephalus - arrow shows ventriculomegaly (increased CSF within ventricles)

Question 13

Spot diagnosis

Answer 13

skull fracture

Question 14

Grey vs White matter + does stroke differentiate?

Answer 14

• Grey matter - neuronal cell bodies (business end)
• White matter - myelinated axons (wiring)

NOTE: stroke doesn’t differentiate between grey and white matter

Question 15

What is sulci effacement (loss of sulci) due to + diffuse / focal

Answer 15

Raised ICP
- Diffuse sulci effacement- generalised brain oedema (e.g. hypoxic-ischaemic injury, meningitis)
- Focal sulci effacement - localised mass effect (tumour, haemorrhage, or infarction)

Question 16

Spot diagnosis - Axial view

Answer 16

Multiple sclerosis

• MRI T2 shows flecks of hyper-attenuated plaques in periventricular regions and corpus callosum

Question 17

Spot diagnosis - Sagittal view

Answer 17

Multiple sclerosis - Dawson’s fingers (radiographic feature of demyelination)

Question 18

Spot diagnosis

Answer 18

Ischaemic stroke - area of hypodensity + loss of grey-white matter differentiation + hyperdense clot in vessel

• note: might be normal in first 6hrs

Question 19

Spot diagnosis

Answer 19

Intracerebral haemorrhage - hyperdense material in brain parenchyma (intraparenchymal)

Question 20

Spot diagnosis

Answer 20

Glioblastoma - irregular thick margins + necrotising centre on MRI

Question 21

Spot diagnosis + cause

Answer 21

Toxoplasmosis (parasite lesion) - shows ring-enhancing lesion

• Cause: from eating undercooked meat - parasite called Toxoplasma gondii

Question 22

Spot diagnosis + cause of symptoms

Symptoms:
- vertigo, unilateral sensorineural hearing loss
- facial palsy
- absent corneal reflex

Answer 22

Vestibular schwannoma - shows lesion on vestibulocochlear nerve
.
- CN VIII - vertigo, unilateral sensorineural hearing loss
- CN VII - facial palsy
- CN V - absent corneal reflex

Question 23

Spot diagnosis

Symptoms: imbalance while walking, abnormal movements and dementia.

Answer 23

Huntington’s disease - caudate head atrophy

Question 24

Spot diagnosis

Answer 24

Hydrocephalus - abnormal accumulation of CSF in ventricles of brain

Question 25

Spot diagnosis + is it benign/malignant

Answer 25

Meningioma - *with dural tail sign* - most are benign

Question 26

What is a chiari malformation + most common type + treatment

Answer 26

- where the cerebellum pushes down into the spinal canal, putting pressure on the spinal cord (MRI shows descent of the causal tip of cerebellar tonsils past the foramen magnum - *the hole in the base of the skull through which the spinal cord passes*) - 4 main types - Type 1 (Chiari I) is the most common - Treatment --> decompression

Question 27

Spot diagnosis (One of the CTs is normal)

Answer 27

Alzheimer's disease - *atrophy of the temporal lobe, particularly hippocampus*

Question 28

Parkinson's MRI - what is the sign called?

Answer 28

- 'swallow tail sign' - *describes the normal axial imaging appearance of a hyperintensity within the substantia nigra*

Question 29

Spot diagnosis

Answer 29

Cytotoxic cerebral oedema - *due to cerebral ischaemia*

Question 30

Spot diagnosis - Symptoms: non-specific, consisting of fever, headache, focal neurological deficits, seizures, and/or altered or decreased level of consciousness

Answer 30

HSV encephalitis

Question 31

Contraindications for MRI

Answer 31

- Metallic implants - *eg. pacemaker, hearing aids, vascular clips* - claustrophobia

Question 32

Which blood vessels in the brain are affected by hypertension?

Answer 32

Lenticulostriate arteries

Question 33

Spot diagnosis

Answer 33

Metastases - *multiple lesions*