Ultrasound

Question 1

What is seen as black on a USS? What is the medical term?

Answer 1

Anechoic- absorb all waves

Blood vessels

Question 2

What is seen as white on a USS? What is the medical term?

Answer 2

Hyperechoic-reflect all waves

Needle

Question 3

What is seen as grey/honeycomb on a USS?

Answer 3

Absorb some but not all waves

Nerves

Question 4

What is acoustic shadowing?

Answer 4

Artefact caused when highly reflective structures stop waves passing through them
E.g a stone- nothing will be seen behind it

Question 5

What is acoustic enhancement?

Answer 5

Artefact caused when less dense/anechoic structures passed through so lighter image is seen behind the shape
E.g a blood vessel- everything behind it will be lighter as more waves are absorbed by the vessel

Question 6

What is high & low frequency used for?

Answer 6

High: Superficial, better imaging
Low: Deeper structures, not as good imaging

Question 7

What does gain determine?

Answer 7

Inc or dec the amount of return to the probe (makes image lighter or darker)

Question 8

What is doppler effect?

Answer 8

Red= Frequency increases, impulse heading towards the probe
Blue= Frequency decreases, impulse heading away from the probe
Can only tell you if there is blood flow not if the vessel is a vein or an artery

Question 9

What is a FAST scan?

Answer 9

Focussed assessment w/sonography for trauma

Question 10

What areas does a FAST scan assess?

Answer 10

Fluid in cavities:
RUQ
LUQ
Suprapubic
Epigastric

Question 11

How would you set up the USS machine for cannulation?

Answer 11

Frequency: High
Depth: Low
Gain: Optimal gain