Table 1.

Essential Ultrasound Terms (Glossary of Terms | American Association of Neuromuscular & Electrodiagnostic Medicine, Jacobson, 2017).

Acoustic impedance	The change in particle velocity in response to a change in pressure (determined by the tissue’s density and the velocity at which sound travels through that tissue).
Anisotropy	The directionally dependent property of a tissue that results in an ultrasound appearance that readily changes depending on the angle of the transducer.
Doppler	A tool to measure flow, with the color red signifying flow towards the transducer and blue indicating flow away from the transducer.
Echogenicity	The ability of a tissue to reflect, rather than absorb, an echo and create brightness in an image. A hyperechoic tissue returns more signal and is therefore bright. A hypoechoic tissue absorbs the signal more than it reflects, resulting in a dark image.
Focal zones	The portion of the image where the ultrasound beam is narrow, creating a hyperechoic appearance relative to the remainder of the image. Its location can be adjusted for image optimization, like the focus on a camera lens.
Gain	The degree of amplification for sound waves returning to the transducer.
Piezoelectric effect	A property of the transducer crystal, that allows electrical signal to be converted into ultrasonic energy that is sent into the tissue. The reflected ultrasonic energy is then converted back into an electrical signal as it returns to the transducer.
Power	The rate of sound energy transferred from the transducer to the tissue.
Transducer/Probe	The extension of the ultrasound that makes contact with the patient. It contains a crystal array that is used both to send and receive ultrasound signals.