US physics, terminology, and Knobology Flashcards
US disadvantages
operator dependent
poor image quality with fat/or air
wavelength relation to frequency
inverse
shorter wavelength
do not penetrate deeply into tissue
but possess high resolution
longer wavelength
penetrate deeply into tissue
but posses low resolution
linear probe is good for
vascular
superficial scanning
sector or phased array probe is good for
cardiac
high frame rate with low freq
curvilinear probe is good for
abdominal
lowest freq with large field of view
purpose of the FAST scan
detect free intraperitoneal fluid, pericadial fluid, pleural fluid, hemothorax and pneumo thorax in trauma pts
morrison’s pouch
right flank between kidney/liver
in FAST look for fluid
anechoic
complete absence of returning sound waves
looks black
characteristic of fluid
hypoechoic
structures that have very few echoes and appear darker than surrounding tissue
hyperechoic
echogenic structures appear brighter than the surrounding tissue
acoustic shadowing
occurs when the sound waves encounter a highly reflective surface
structures deep appear hypoechoic or anechoic
gallstones are a good example
posterior acoustic enhancement
common artifact
occurs deep to an anechoic structure
due to an increase in echogenecity posterior to an anechoic structure because the sound waves lose little energy traveling through a fluid filled structure
bladder is a good example…. area behind the structure will look very bright
Edge artifact
sound is refracted (bent) by a structure in parallel with the US beam and does not return to the probe
generally seen when an imaging fluid-filled structure like the gallbladder or vessels in transverse imaging
