TERM 1
Acoustic Impedance
DEFINITION 1
Relationship between density or stiffness of tissue and the
velocity of sound within the tissue. Differences in acoustic
impedance of adjacent tissues determine the intensity of
reflected sound.
TERM 2
Acoustic shadow
DEFINITION 2
Ultrasound artifact. Echo-free zone created distal to the
imaged organ when sound waves hit a highly reflective tissue
that prevents sound from being transmitted to greater
depths.
TERM 3
Anechoic
DEFINITION 3
No echoes are detected, and the area is black. Typically
associated with fluid-filled structures such as the urinary
bladder.
TERM 4
Attenuation
DEFINITION 4
Reduced intensity of radiation caused by absorption or
scattering, or both, during passage through tissue. Sound is
also attenuated as it passes through tissue and the intensity
is reduced.
TERM 5
B-Mode (Brightness-mode) Ultrasonography
DEFINITION 5
Intensity of returning echoes is expressed as brightness in
the display.
