Recommended Ultrasound Terminology
U
ultrafast Doppler
A technique that employs plane wave compounding with multiple transmissions per direction and high speed data collection to achieve imaging of flow about an order of magnitude faster than ordinary Doppler flow. Another advantage of this method is that the Doppler spectrum can be displayed at any point in the image.
Related term: ultrafast ultrasound techniques
ultrafast ultrasound technique
A method that uses massive parallel receive beamforming and plane wave imaging techniques to achieve an ultra-high imaging frame rate (e.g., up to 20,000 Hz).
ultraharmonic
An oscillation at a frequency that is an odd integer multiple (greater than 1) of half the fundamental frequency of the oscillation (3/2f0, 5/2f0...).
ultraharmonic imaging
An imaging technique used to enhance the contrast between echoes from ultrasound contrast agents and tissue echoes. It employs pulse sequences in which excitations of microbubbles produce ultraharmonic echoes which can be differentiated from echoes arising from tissue.
See ultraharmonic.
ultrasonic
Pertaining to sound at frequencies higher than that which can be detected by the human ear. Usually refers to sound with a frequency greater than 20 kHz.
ultrasonic pulse
A short burst of ultrasound that is transmitted into the body by a pulse-echo ultrasound instrument.
ultrasonic scan line separation
For automatic scanning systems, the distance or angle between the points of intersection of two specified consecutive ultrasonic scan lines of the same type with a specified plane. The unit is meter (m).
ultrasonic shadow
See acoustic shadow (see Figure 16).
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ultrasonic tissue characterization
Usage of pulse-echo or through-transmission ultrasound data to detect, extract, and display quantitative information about tissue function, structure, and pathology.
ultrasonic transducer
A device that converts ultrasonic energy into an electrical signal and vice versa.
Related term: transducer
ultrasonic transducer element group
A group of elements of an ultrasonic transducer that are excited together to produce a single acoustic pulse.
ultrasonogram
See sonogram.
ultrasonography
See sonography.
ultrasound
Acoustic oscillation whose frequency is above the high-frequency limit of audible sound (about 20 kHz).
ultrasound computed tomography (UCT)
Tomography utilizes ultrasound, usually with ultrasound apertures of a few elements sited opposite each other in a transmit receive mode situated on a horizontal ring. The ring can be moved vertically to obtain a three dimensional image, or a two dimensional array on a semi-spherical surface can be used. Different parameters other than magnitude can be visualized such as absorption and the speed of sound.
Related term: tomography
ultrasound dosimetry
The measurement of the quantity of ultrasound energy that is absorbed when a subject is exposed to an ultrasound beam. The unit is joule (J).
Related term: Compare with ultrasound exposimetry
ultrasound exposimetry
The measurement of the quantity of ultrasound to which a subject is exposed.
Related term: Compare with ultrasound dosimetry
ultrasound instrument console
Electronic unit to which the transducer assembly is attached.
ultrasound localization microscopy (ULM)
A technique that enhances the resolution of conventional ultrasound imaging beyond the diffraction limit by localizing and tracking individual microbubbles in the bloodstream.
Related term: functional ultrasound localization microscopy (fULM), super-resolution ultrasound imaging
ultrasound research system
An ultrasound system intended for research and technical development purposes, which can be programmed by the user to achieve new functions.
ultrasound therapy
See therapeutic ultrasound.
ultrasound-induced bioeffect
A change in the structure or function of a biological structure resulting from exposure to ultrasound.
ultrasound-mediated drug delivery
An ultrasound technique that enhances the delivery of drugs into the target tissue. Often, this technique relies on the interaction of ultrasound energy with systemically circulating microbubble contrast media to reversibly disrupt nearby cell and neovascular membranes and enable uptake of the therapeutic agent.
ultrasound-stimulated gene delivery
An ultrasound technique that enhances the delivery of gene therapy vectors into the target. Often, this technique relies on the interaction of ultrasound energy with a systemically circulating microbubble contrast medium to reversibly disrupt nearby cell and neovascular membranes and enable uptake of the genetic material.
unbiased estimator
An estimator for which its expected value equals the true mean value.
uncoupled mode
A normal mode oscillating independently of other modes.
undamped natural frequency
Frequency of free oscillation resulting from only elastic and inertial forces of the system.
Related term: resonance frequency
unenhanced sonography
Sonography in which a contrast agent is not used.
unidirectional hydrophone
Directional hydrophone the response of which has a prominent maximum for one direction of the sound wave.
uniform insonation method
An ultrasonic method used in the estimation of volume flow in which Doppler signals are acquired equally from an entire cross section of the vessel being interrogated.
unipolar pulse or waveform
A waveform that has either positive or negative excursions from the baseline but not both. A unipolar waveform can be produced by rectification of radio frequency signals.
user interface
The part of an ultrasound system by which the user can configure the system to work in a desired mode of operation. The user interface also provides the means of transferring information into and out of the system, as well as controlling and displaying parameters of an ultrasound imaging system.
