Ultrasound Tutorial Flashcards
What is ultrasound imaging?
Imaging modality using high frequency sound waves that can be used to image structures
How are US waves generated?
Electric field applied to piezoelectric crystal in the transducer causes its vibration
What happens when a sound wave encounters a change in tissue type/density?
Some waves are transmitted and others are reflected = reflected waves are used to generate an image
How is depth calculated?
Using the time it takes for US waves to return
What are the features of higher frequency US waves?
Have shorter wavelength so produce better image resolution
Have less depth penetration so can only be used to examine relatively superficial structures
What is the Doppler effect?
Frequency of transmitted sound is altered as it is reflected from moving object = can be used to examine flow
What should be between the skin and the probe using US?
Acoustic coupling gel must be between skin and probe
How can you tell direction of flow when using a colour Doppler?
Blue = flow is moving away from you Red = flow moving towards you
How can you optimise the image on a US?
Pressure = minimise distortion Align = move across skin surface and follow structures Rotate = twist to get true short axis view Tilt = rock to obtain best view possible
How does bone appear on US?
Hyperechoic periosteum with acoustic shadow below
How do vessels appear on US?
Artery = anechoic, pulsatile, usually round Vein = Anechoic, non-pulsatile, compressible
How do nerves appear on US?
Circular or oval
Hyperechoic outline and speckled interior
More proximal nerves have predominantly hyperechoic interior
How do tendons appear on US?
Similar to nerves = blend into muscle proximally and become more prominent distally
How does muscle appear on US?
Hypoechoic mass = may have visible striae or hyperechoic fascia
What is acoustic shadowing?
Dark shadow appears behind an acoustically opaque structure is in line of US
