Neuroradiology Flashcards

1
Q

What are the common indications to perform a CT?

A
  • Stroke
  • Head trauma
  • Headache
  • Cancer
  • Post-surgical (hydrocephalus, haemorrhage)
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2
Q

When may you not perform a CT scan?

A
  • Minor head trauma exclusion criteria

- Seizure

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3
Q

When would a CT not be carried out for a head trauma?

A
  • GCS 15
  • No suspected open or depressed skull fracture
  • No hemotympanum
  • No ‘panda’ eyes
  • No CSF leakage from ears or nose
  • No post -traumatic seizure
  • No focal neurological deficit
  • <2 episodes of vomiting
  • No amnesia
  • Age<65 years
  • No coagulopathy
  • Not struck by a motor vehicle,
  • Not ejected from a motor vehicle
  • Fall<1m
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4
Q

What are the indications for an MRI scan?

A
  • Epilepsy
  • Demyelination
  • Paediatric neurology
  • Headache
  • Spine degeneration
  • Cancer
  • Stroke
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5
Q

What are the contraindications to MRI scan?

A
  • Implanted electronis such as pacemakers and cochlear implants
  • Movable metallic implants such as aneurysm clips, heart valves or intrabdominal clips
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6
Q

What is angiography used in the diagnosis and treatment of?

A
  • Aneurysm
  • Arteriovenous malformations
  • Carotidocavernous fistula
  • Unstoppable epitaxis
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7
Q

Perfusion

A

The volume of blood passing through a defined volume of tissue per unit time

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8
Q

What techniques can be used for perfusion?

A

CT or MRI

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9
Q

What is the units of perfusion?

A

ml blood/100g tissue/ min

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10
Q

Give examples of disorders of abnormal perfusion.

A
  • Stroke decreases perfusion

- Tumour with increased perfusion suggest angiogenesis and a more aggressive tumour

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11
Q

What is PET used to do?

A

Map out glucose usage

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12
Q

When can increased metabolism be seen?

A
  • Tumour
  • Inflammation
  • Infection
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13
Q

When is PET useful?

A

Useful after brain tumour resection for differentiating granulation tissue (low energy use) from leftover tumour (high energy use)

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14
Q

What are the clues to recognising plain film radiographs?

A
  • Multiple superimposed bones
  • Soft tissue is grey
  • Air is black
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15
Q

What are the clues to recognising CTs?

A
  • White circle of skull
  • Black CSF in sulci and ventricles. Air is black
  • Grey brain with subtle grey-white difference
  • Image quality: reconstructed by back projection from rotating fan beam of X-rays. Beam hardening from radio dense objects
  • Metal produces white starburst artefacts
  • Slightly grainy
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16
Q

What are the clues to recognising MRIs?

A
  • White CSF is the best clue, but only true for T2-weighted MRI
  • Same anatomy with different sequences often shown
  • Better grey-white matter differentiation than CT
  • The skull is a thin black circle, immediately surrounded by a white circle of subcutaneous fat
  • Image quality: reconstructed from Fourier transforms of radio signals
  • Has a JPEG like quality, usually not grainy
17
Q

What are the clues to recognising PETs?

A
  • Images often have bright and varied colour

- The image is fuzzy

18
Q

What are the clues to recognising US?

A
  • Wedge-shaped image with the edges of the image diverging away from top to bottom
  • Often has a curve at the top matching the ultrasound probe (exception: flat probes)
  • Noisy image
  • Objects which block the ultrasound beam (air, bone, stones) casts shadows cast downwards
19
Q

What are the advantages of plain radiographs?

A
  • Almost universal availability
  • Fast
  • Sequential images in subtraction angiography
20
Q

What are the disadvantages of plain radiographs?

A

Lacks soft tissue detail

21
Q

What are the advantages of ultrasound?

A
  • No radiation
  • Less expensive
  • Can be performed in the neonatal unit
  • Movement tolerant
22
Q

What are the disadvantages of ultrasound?

A
  • Requires a wide enough open fontanelle (up to about 1 year)
  • Image quality and interpretation based on operator skill
23
Q

What are the advantages of CT?

A
  • Rapid
  • Metal and pacemaker tolerance
  • Good for demonstrating acute haemorrhage
24
Q

What are the disadvantaged of CT?

A
  • Radiation 2mSv

- More expensive cumbersome equipment

25
Q

What are the advantages of radionuclide imaging?

A

Physiological information

  • Glucose metabolism
  • Perfusion
  • Dopamine reuptake receptors
26
Q

What are the disadvantages of radionuclide imaging?

A
  • Unclear anatomical information
  • Medium cost of equipment
  • Radiotracers can be very expensive
27
Q

What are the advantages of MRI

A
  • No radiation
  • Soft tissue differentiation
  • Physiological information
    • Blood flow
    • Diffusion restriction
    • Metabolite concentrations
28
Q

What are the disadvantages of MRI?

A
  • Poor tolerance of metalwork
  • Magnetic sensitive electronics may fail or are contraindicated (Pacemakers, Cochlear implants absolutely)contraindicated
  • Least movement tolerance
  • Slow, must limit sequences
  • Most expensive equipment
  • Danger of metallic objects becoming projectiles
29
Q

What are the relative contraindications for MRI?

A
  • Claustrophobia
  • Pregnancy
  • Tattoos