Session 12- imaging Flashcards Preview

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Flashcards in Session 12- imaging Deck (18):

When do we use radiographs?

  • If there is trauma
  • Can look at mandible, facial bones etc. 
  • If there is an abnormality it is a sign that further imaging is needed 


What is the normla projection of a head x ray?

PA (same as for chest X-ray)


Why are lead aprons used during radiographs?

To protect damage to other organs e.g. thyroid, lens and gonads 


What is US good for looking at?


Soft tissues e.g. lymph, thyroid 


What are avantages and disadvantages of CT?

  • Advantages 
    • Quick
    • Gives lots of information, on soft tissue and bone
    • Gives 3D image, cross-sectional views of anatomy and allws bone, soft tissue and brain to be viewed in detail 
    • Can see vessels etc. and fat, muscles, pharynx , larynx ... ltos of things 
  • Disadvantages
    • Uses lots of radiation, must justify use (as involves many x-ray images taken from multiple angles) 


when should you not do an MRI?

  • If patient has pacemaker, cochlear implants or if there are radio-opaque foreign bodies seen


In a blow out fracture what sinus is fluid likely to collect in, or contents of the orbit likely to herniate into?

The maxillary sinus 


What is MRI good at looking at?

Soft tissue e.g. muscles, not so god for bone 


N.B. takes a lot longer than CT 



If someone has renal impairment what shouldn't be used?

 Contrast (it can cause a reaction in some patients)


Which types of USS is used to assess flow?

Doppler (gives a coloured image) 


What does fluid appear like on a T1 compared to a T2 MRI scan?

  • T1- fluid is dark 
  • T20- fluid is white 


How does fluid appear on USS?



If there is fluid seen on MRI infront of the vertebral column, what is it likely to be?

Pre-vertebral abscess


When can a CT airway assessment be used?

Gives a good image of the airways, can be used in patients with big goitres before surgery so anaethetist can see if there is any airway compromise 


In clinical practice what is the most used imaging method?Why?

  • X-ray
    • It is cheap, readily available, relatively low radiation compared to CT
    • BUT doesn't show soft tissue, head and neck often requires CT 

- can check for abnormality by looking for any breaks in the continuity of borders etc. 



MRI provides cross sectional, 3D images like CT. What is the difference?

  • Uses magnetic fields and radio-waves rathr than ionising radiation
  • Soft tissue detail seen e.g. muscle is much better than with CT 
  • BUT MRI is more expensive than CT and imaging process takes much longer (up to 30 mins)