Neuroradiology Flashcards

1
Q

What are common indications for head CT scan?

A
  • Head trauma
    • NICE guidelines
  • Acute stroke
    • NICE guidelines
  • Headache
    • SIGN guidelines, red flags for suspected tumour or subarachnoid haemorrhage
  • Cancer
    • Looking for metastatic brain tumours in patients with symptoms
  • Post-surgical
    • Hydrocephalus, haemorrhage
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2
Q

What are contraindications for head CT scan?

A

For head trauma follow NICE and SIGN guidelines:

  • Such as GCS score of 15, no suspected open or depressed skull fracture, no CSF leakage from ears or nose, no post-traumatic seizure etc

NICE guidelines for seizure usually suggest MRI:

  • Primary idiopathic generalised epilepsy
    • No imaging
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3
Q

What are indications to perform MRI scan?

A
  • Neurologists
    • Demyelination
      • Such as to help diagnose MS
    • Epilepsy
      • NICE and SIGN guidelines (and if surgery is contemplated)
    • Paediatric neurology
      • Disorders of development, head circumference, congenital malformation
    • Headache
      • Benign intracranial hypertension
  • Surgeons
    • Spine
      • Intervertebral disc degeneration causing neural compression
    • Cancer
      • Clarifying the number, location and aggressiveness of brain tumours
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4
Q

What are contraindications to performing MRI scan?

A

Implanted electronics (check with manufacturer):

  • Cardiac pacemakers, implantable defibrillators, cochlear implants
  • Relative contraindication for programmable shunts, insulin pumps

Moveable metallic implants (check make and model):

  • Aneurysm clips, heart valves, recent intra-abdominal clips

Relative contraindications:

  • Claustrophobia, pregnancy, tattoos
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5
Q

When is angiography used in neurology?

A

Large vascular (arterial and venous) abnormalities

Diagnosis and treatment of:

  • Aneurysm
  • Arteriovenous malformation
  • Carotidocavernous fistula
  • Unstoppable epistaxis
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6
Q

What is perfusion?

A

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

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7
Q

What are the units of perfusion?

A

Units are ml blood, 100g tissue or per minute

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8
Q

Is perfusion measured using CT or MRI?

A

Either, you get CT perfusion or MRI perfusion

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9
Q

What are some disorders of abnormal perfusion?

A
  • Stroke
    • Decreased perfusion
  • Tumour
    • Increased perfusion indicates angiogenesis and a more aggressive tumour
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10
Q

Is the perfusion in a stroke increased or decreased?

A

Decreased

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11
Q

Is the perfusion in a tumour increased or decreased?

A

Increased perfusion (indicates angiogenesis and a more aggressive tumour)

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12
Q

What are PET scans used for?

A

Usually used to map out glucose usage

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13
Q

Increased metabolism of glucose is seen in what?

A
  • Tumour
  • Inflammation
  • Infection
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14
Q

Why are PET scans useful after brain tumour resection?

A

Differentiating granulation tissue (low energy use) from leftover tumour (high energy use)

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15
Q

What are clues for identifying that an image is a plain radiograph?

A
  • Multiple superimposed bones, bones are white
  • Immediately recognisable body parts
  • Soft tissue is grey
  • Air is black
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16
Q

What colour is air in a x-ray?

17
Q

What colour is soft tissue in a x-ray?

18
Q

What are clues for indentifying an image is a CT scan?

A
  • White circle of skull
  • Black CSF in sulci and ventricles, air is black
  • Grey brain with subtle grey white matter difference
  • Image quality
    • Reconstructed by back projection from a rotating fan beam of x-rays
    • Beam hardening from radiodense objects
      • Metal produces white starbust artefacts
    • Slightly grainy
19
Q

What colour is the skull in a CT scan?

20
Q

What colour is CSF in a CT scan?

21
Q

What colour is air in a CT scan?

22
Q

What colour is the brain in a CT scan?

A

Grey with subtle grey white matter differences

23
Q

What are clues an image is a MRI scan?

A
  • White CSF is the best clue (but only true for T2 weighted MRI)
    • Same anatomy with different sequencing often shown
  • Better grey-white matter differentiation than CT
  • Image quality
    • Reconstructed from Fourier transforms of radio signals
    • Has a JPEG like quality, usually not grainy
24
Q

What colour is CSF in a MRI scan?

25
What are clues an image is a radionuclide radiology/nuclear medicine/PET image?
* Images often have bright and varied colours * The image is fuzzy
26
What are clues an image is an ultrasound?
* 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 is flat probes) * Very noisy image (like an old un-tuned TV) * Objects which block the ultrasound beam (air, bone, stones) cast shadows downwards
27
What are some examples of important neurological emergencies?
* Trauma * Acute stroke * Cauda equine compression * Subarachnoid haemorrhage
28
What is helpful when discussing neuroradiology referrals?
* For stroke * Know about carotid arteries, cardiovascular risk and atrial fibrillation as well as functionally important areas of the brain * Be able to differentiate upper motor neuron from lower motor neurone * For cauda equine syndrome or intervertebral disk herniations you should be able to link reflexes and dermatomes to approximate spinal levels and be able to number vertebrae
29
What are advantages and disadvantages of US?
* Advantages * No radiation * Less expensive equipment * Can be performed in the neonatal unit * Movement tolerant * Disadvantages * Requires a wide enough fontanelle (ie about up to 1 year of age) * Image quality and interpretation based on operator skill
30
What are advantages and disadvantages of plain radiographs?
* Advantages * Almost universally available * Fast * Sequential images in subtraction angiography * Disadvantages * Lacks soft tissue detail
31
What are advantages and disadvantages of CT?
* Advantages * Rapid * Metal and pacemaker tolerance * Good for demonstrating acute haemorrhage * Disadvantages * Radiation 2mSv * More expensive cumbersome equipment
32
What are advantages and disadvantages of radionuclide radiology?
* Advantages * Physiological information * Glucose metabolism * Perfusion * Dopamine reuptake receptors * Disadvantages * Unclear anatomical information * Medium cost of equipment * Radiotracers can be expensive
33
What are advantages and disadvantages of MRI?
* Advantages * No radiation * Soft tissue differentiation * Physiological information * Blood flow * Diffusion restriction * Metabolite concentrations * Disadvantages * Poor tolerance of metalwork * Magnetic sensitive electronics may fail ore are contraindicated * Pacemakers * Cochlear implants absolutely contraindicated * Least movement tolerance * Slow, must limit sequence * Most expensive equipment Danger of metallic objects becoming projectiles