Neuroradiology Flashcards

1
Q

list indications to perfomr a 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 Flexible, common-sense, happy to discuss

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2
Q

what are the reasons not to perform a CT scan?

A

Minor head trauma exclusion criteria: NICE and SIGN guidelines

– primary idiopathic generalised epilepsy – no imaging – complete recovery after a first seizure is not epilepsy

Seizure: NICE guidelines (pg 16), usually choose MRI
I suggest that the detail in guidelines are not fair game for exams and that guidelines may change by the time you qualify
– Do be aware that guidelines exist for these conditions

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3
Q

list indications to perform MRI

A

Neurologists

Epilepsy: NICE and SIGN guidelines (and if surgery is contemplated)

Demyelination: for example, to help diagnose multiple sclerosis

Paediatric neurology: disorders of development, head circumference, congenital malformations

Headache: benign intracranial hypertension

Surgeons

Cancer: clarifying the number, location and aggressiveness of brain tumours

Spine: Intervertebral disc degeneration causing neural compression

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4
Q

contraindications to perform an 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

uses of angiography

A

Large vascular (arterial and venous) abnormalities Diagnosis and treatment

  1. Aneurysm
  2. Arteriovenous malformation
  3. Carotidocavernous fistula 4. Unstoppable epistaxis
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6
Q

what are the uses of CT perfusion?

A

Stroke – decreased perfusion

Tumour – increased perfusion indicates angiogenesis and a more aggressive tumour

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7
Q

what are the uses of PET scan?

A

PET is usually used to map out glucose usage Increased metabolism is seen in
Tumour
Inflammation
Infection

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

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8
Q

characteristics of a plain radiograph?

A
Plain radiographs
• • • •
Multiple superimposed bones, bones are white 
Immediately recognisable body parts
Soft tissue is grey
Air is black
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9
Q

characteristics of 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

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10
Q

characteristics of MRI?

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 Image quality:
– reconstructed from Fourier transforms of radio signals
– has a JPEG-like quality, usually not grainy

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11
Q

characteristics of an ultrasound?

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)
Very noisy image (like an old un-tuned TV)
Objects which block the ultrasound beam (air, bone, stones) cast shadows cast downwards

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12
Q

advantages of US

A
No radiation
• Less expensive equipment
• Can be performed in the
neonatal unit
• Movement tolerant
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13
Q

disadvantages of US

A

Requires a wide enough open fontanelle i.e. up to about 1 year of age
• Image quality and interpretation based on operator skillRequiresawide enoughopenfontanelle i.e. up to about 1 year of age
• Image quality and interpretation based on operator skill

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14
Q

advantages of plain radiograph

A

Almost universal availability
• Fast
• Sequentialimagesin
subtraction angiography

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15
Q

disadvantages of plain radiographs

A

lacks soft tissue detail

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16
Q

advantages of CT

A
Rapid
• Metal and pacemaker
tolerance
• Good for demonstrating
acute haemorrhage
17
Q

disadvantages of CT

A

Radiation 2mSv •
More expensive
cumbersome equipment

18
Q

advantages of radionuclide radiology

A

Physiological information:
• Glucose metabolism
• Perfusion
• Dopamine reuptake receptors

19
Q

disadvantages to radionuclide radiology

A

Unclear anatomical information
• Mediumcostofequipment • Radiotracerscanbe
expensive

20
Q

advantages to MRI

A
No radiation
• Soft tissue differentiation 
• Physiologicalinformation:
• blood flow
• diffusion restriction
• metabolite concentrations
21
Q

disadvantages to MRI

A

Poor tolerance of metal work • Magnetic sensitive
electronics may fail or are contraindicated
• Pacemakers!
• Cochlear implants absolutely contraindicated
• Leastmovementtolerance • Slow,mustlimitsequences • Mostexpensiveequipment • Dangerofmetallicobjects
becoming projectiles