Ultraharmonic is an oscillation at a frequency that is a rational multiple of that of its fundamental sinusoidal oscillation, for example 1.5 or 2.5 times the fundamental frequency. Ultraharmonic imaging is a method to eliminate tissue artifacts and therefore increase contrast to tissue ratio.
Also called Superharmonic Imaging.

See also Power Modulation.

Ultrasonography is another term[aka: sonography] used to describe the practice of using ultrasound technology for diagnostic imaging. It is synonymous with sonography and signifies the process of capturing ultrasound images, regardless of the body part or condition being examined. Ultrasonography is widely utilized in various medical imaging specialties, including obstetrics and gynecology, cardiology, radiology, urology, and many others. It has proven to be particularly valuable in obstetric imaging, allowing healthcare providers to monitor the growth and development of a fetus during pregnancy.
Ultrasonography uses the reflections of high-frequency sound waves to construct an image of a body organ. These ultrasonic waves are generated by a quartz crystal and are reflected at the interface between different tissues. The transmission and reflection of these high-frequency waves are displayed with different types of ultrasound modes.
See also sonogram, sonography, ultrasound imaging.

(US) Ultrasound is very high frequency sound above about 20,000 Hertz. Any frequency above the capabilities of the human ear is referred to as ultrasound.
Diagnostic ultrasound imaging uses much higher frequencies, in the order of megahertz. The frequencies present in usual sonograms can be anywhere between 2 and 13 MHz. The sound beam produce a single focused arc-shaped sound wave from the sum of all the individual pulses emitted by the transducer.

See also Medical Imaging.

The traveling ultrasonic wave causes a low-level ultrasound radiation force when this energy is absorbed in tissues (absorbed dose). This force produces a pressure in the direction of the beam and away from the transducer. It should not be confused with the oscillatory pressure of the ultrasound wave itself. The pressure that results and the pressure gradient across the beam are very low, even for intensities at the higher end of the range of diagnostic ultrasound. Mechanical effects like radiation forces lead to stress at tissue interfaces. The effect of the force is manifest in volumes of fluid where streaming can occur with motion within the fluid. The fluid velocities which result are low and are unlikely to cause damage.
The effects of ultrasound radiation force (also called Bjerknes Forces) were first reported in 1906 by C. A. and V. F. K. Bjerknes, when they observed the attraction and repulsion of air bubbles in a sound field.
While incompressible objects do experience radiation forces, compressible objects driven at their resonant frequency experience far larger forces and can be observably displaced by low-amplitude ultrasound waves. A microbubble driven near its resonance frequency experiences a large net radiation force in the direction of ultrasound wave propagation. Ultrasound pulses of many cycles can deflect resonant microbubbles over distances on the order of millimeters.
In addition to primary radiation force, which acts in the direction of acoustic wave propagation, a secondary radiation force for which each individual bubble is a source and receptor causes the microspheres to attract or repel each other. The result of this secondary force is that a much larger concentration of microbubbles collects along a vessel wall than might otherwise occur.

See also Acoustically Active Lipospheres.

From GE Healthcare.;
'GE is defining a new age of ultrasound. We call it Volume Ultrasound. GE's Voluson 730 Expert is a powerful system that enables real-time techniques for acquiring, navigating and analyzing volumetric images so that you can make clinical decisions with unprecedented confidence.'