CSIM 1.72: Introduction to Imaging Modalities Ultrasound and MRI

Question 1

Black on an ultrasound image means what?

Answer 1

That sound waves are passing through (liquid), white means sound is being reflected (solid)

Question 2

White on MRI means what?

Answer 2

White - high proton content
• Bone is white
• Dense CT is dark grey
• Fluid is black

Question 3

What are the strengths and weaknesses of MRI imaging?

Answer 3

Strengths
• No radiation
• Good soft tissue detail/contrast
• 3D

Weaknesses
• Magnetic objects cant enter
• Slow and have to stay still
• Lots of artefacts

Question 4

What are the strengths and weaknesses of ultrasound imaging?

Answer 4

Strengths
  •  Completely safe
  •  Portable
  •  Cheap 
  •  Good for locating source of pain or masses acutely

Weaknesses
  •  Cannot pass gas
  •  Cannot pass bone
  •  Does not pass through fat very well
  •  ^^ all due to impedance differences