Terms Flashcards
(20 cards)
What is attenuation?
The loss and absorption of ultrasound energy through a medium
What is absorption?
Ultrasound energy converted to heat energy in tissue
What is refraction?
Two adjacent tissues have slightly different impedance values (resistance)
What is reflection?
When two adjacent tissues have significantly different impedance values
How many Hz is considered ultrasonic?
For than 20 000Hz
What is Hyperechoic?
Large amount of unattenuated sound waves reflected back
Define hypoechoic
Small amount/highly attenuated sound waves reflected back
What is anechoic
No sound waves reflected back
What is echo brightness
The amount of sound waves reflected back to the transducer in relation to the amount of attenuation in the tissue
Examples of hyperechoic tissue
Bones
Stones
Connective tissue
Fatty tissue
Examples of hypoechoic structures
Tumors
Abscess
Lymph nodes
Examples of anechoic structures
Large vessels
Free fluid
Bladder
What is reverberation?
When an ultrasound bean encounters two strong parallel reflectors
What is an A-line?
Result from sound reflecting between two parallel closely apposed reflective surfaces
What are B-lines?
A thin vertical echo genie line of reverberation that passes from the point of origin to the deepest part of the ultrasound image.
What is a comet tail?
A short path reverberation artefact that weakens with each reverberation
What is acoustic shadowing?
Where ultrasound waves are highly attenuated behind a reflective surface
What is acoustic enhancement?
When tissue appears brighter behind fluid filled structures due to lesser degree of attenuation
What is edge shadowing?
Ultrasound at the edge of a structure reflected away
What is a ring-down artefact?
B-line artefacts in parts other than the lungs
