Workbook - Neuroradiology Flashcards
What direction are conventional CTs viewed from?
Below, with the patient looking up.
(^ = anterior, > = left,
What sort of images are CTs?
Axial images.
-not truly horizontal
What are the main differences between CT and MRI?
CT: - x-rays (radiation)
- cost; medium
- contraindications; pregnancy
- best detail; bone
MRI: -magnetic fields (no radiation)
- cost; high
- contraindications; metal implants
- best detail; soft tissue
When are CTs commonly used for in neuroimaging?
Stroke, tumour, head injury.
When are MRIs most useful?
Haemorrhage, ischaemia.
-pituitary gland & brainstem
What appears bright (AKA hyperdense) on CT?
Blood
Bone
What appears bright (AKA hyperdense) on T1 weighted MRI?
Fat
Protein
Melanin
Contrast
What appears bright (AKA hyperdense) on T2 weighted MRI?
Fluid
What appears dark (AKA hypodense) on CT?
Oedema
CSF
Chronic blood
What appears dark (AKA hypodense) on T1 weighted MRI?
Fluid
What appears dark (AKA hypodense) on T2 weighted MRI?
Fat
In what type of scan is bone very white?
CT scan.
Which regions of the brain does the anterior cerebral artery supply?
- Medial and upper frontal lobe
- Superior parietal lobe
Which regions of the brain does the middle cerebral artery supply?
- Most of lateral surface (except upper parietal and frontal lobes, and inferior temporal)
- Broca’s area
- Wernicke’s area
Where is Broca’s area located?
Lateral inferior frontal lobe.
Where is Wernicke’s area located?
Lateral temporal lobe.
Which regions of the brain does the posterior cerebral artery supply?
- Inferior/medial temporal lobe
- Occipital lobe (midbrain & thalamus)
What is TACI?
Total Anterior Circulation Infarct.
-cerebral infarction that affects anterior circulation affecting one side of the brain
» motor and sensory defects, dysphasia, etc.
What is PACI?
Partial Anterior Circulation Infarct.
-cerebral infarction that affects part of anterior circulation affecting one side of the brain
» partial motor and sensory defects, dysphasia, etc
What is POCI?
POsterior Circulation Infarct.
-cerebral infarction that affects posterior circulation affecting one side of the brain
» nerve palsy, bilateral motor and sensory defects, cerebellar dysfunction
What is a lacunar stroke (LACI)?
Stroke due to occlusion of one of the penetrating arteries to the brain’s deep structures.
What are the CT findings for a right-sided infarct? (2)
- Loss of grey-white differentiation
- Oedema on right
How will patients with right-sided infarct due to the middle cerebral artery present?
- Expressive aphasia
- Contralateral weakness
How does acute infarct appear on a CT?
Hyperdense / bright.
How does subacute infarct appear on a CT?
Isodense / grey.
How does chronic infarct appear on a CT?
Hypodense / dark.
What type of scan should be used for imaging the posterior fossa?
MRI.
What are the anatomical components of the basal ganglia? (3)
- Corpus striatum (caudate & lentiform nuclei)
- Substantia nigra
- Subthalmic nucleus
What is a subarachnoid haemorrhage?
Bleeding into the subarachnoid space.
-spontaneous / due to head injury
What type of vessel is involved in a subarachnoid haemorrhage?
Circle of Willis artery.
What is the distinctive symptom for a subarachnoid haemorrhage?
‘Thunderclap’ headache.
-nausea, photophobia, double vision
What is a subdural haemorrhage?
Bleeding between dura mater and arachnoid mater.
What type of vessel often causes a subdural haemorrhage?
Tearing in a small bridging vein.
e.g. due to head injury
What is an extradural haemorrhage?
Bleeding between dura mater and the skull.
What is a common cause of an extradural haemorrhage?
Trauma/skull fracture»_space; torn meningeal artery (normally middle).
What are the characteristics of an extradural haemorrhage scan?
Large lentiform bleed.
-lens shaped
How is an extradural haemorrhage treated?
Burr hole»_space; reduce ICP.
-medical emergency
What is a contre-coup injury?
Impact to head»_space; injury on opposite side of brain.
What vessel is responsible for a right occipital infarct?
Posterior cerebral artery.
Why might a patient with a right occipital infarct present with a left homonymous hemianopia?
Brain contains visual pathways to opposite side.
-damage»_space; opposite visual field loss
What are the distinguishing features of a haemorrhagic stroke? (3)
- Bright blood
- Mass effect
- Blood vessel in brain burst
What are the distinguishing features of an ischaemic stroke? (4)
- Bright thrombus in vessel (blocks blood flow)
- Loss of grey/white differentiation
- Oedema (dark/hypodense)
- Mass effect
What causes a haemorrhagic stroke?
Aneurysm burst or weakened vessel (leak) in the brain.
What causes an ischaemic stroke?
Blood clot blocks the flow of blood and oxygen to the brain.
-e.g. due to atherosclerosis
What is the most common type of stroke?
Ischaemic stroke.
