Echogenicity is the ability of a medium to create an echo, for example to return a signal when tissue is in the path of the sound beam. The ultrasound echogenicity is dependent on characteristics of tissues or contrast agents and is measured by calculating the backscattering and transmission coefficients as a function of frequency.
The fundamental parameters that determine echogenicity are density and compressibility. Blood is two to three orders of magnitude less echogenic than tissue due to the relatively small impedance differences between red blood cells and plasma. The tissue echogenicity can be increased by ultrasound contrast agents. Encapsulated microbubbles are highly echogenic due to differences in their compressibility and density, compared to tissue or plasma.
Microbubbles are 10,000 times more compressible than red blood cells. The compressibility of air is 7.65 x 10−6 m2/N, in comparison with 4.5 x 10-11 m2/N for water (on the same order of magnitude as tissue and plasma). This impedance mismatch results in a very high echogenicity. An echo from an individual contrast agent can be detected by a clinical ultrasound system sensitive to a volume on the order of 0.004 pl.

See also Isoechogenic, Retrolenticular Afterglow, and Sonographic Features.

From GE Healthcare;;
Optison is the first 'second generation USCA' marketed in the US.
Ultrasound contrast agents used during an ultrasound imaging procedure, enable more accurate diagnosis of the patient's heart condition. The application of Optison allows to image the endocardial borders of the heart, to see cardiac wall motion abnormalities and to guide the selection and monitoring of treatment.
Optison represents a class of microbubbles with a shell formed by sonicating a solution of capsules filled with a perfluoropropane gas. The high molecular weight slows microbubble dissolution and prolongs the enhancement for several minutes. The human albumin-stabilized cavitation bubbles have a surface tension of 0.9 N/m and a surface dilatational viscosity 0.08 msP.

'August 06, 2001 Molecular Biosystems Inc., a subsidiary of Alliance Pharmaceutical Corp, announced the amendment of the Optison Product Rights Agreement (OPRA) dated May 9, 2000 with Mallinckrodt Inc, a unit of Tyco Healthcare. Optison, an intravenous ultrasound contrast agent, was developed by MBI and is being marketed by Mallinckrodt in the U.S. and Europe. Under the amended agreement, MBI will receive an immediate cash payment plus additional unspecified royalties for a two-year period. The amendment of OPRA coincides with an announcement by Nycomed Amersham Imaging that Nycomed and Mallinckrodt will terminate their joint commercialization and development agreement for ultrasound contrast agents, including Optison, effective Dec. 31, 2001. Effective Jan. 1, 2002, all selling and marketing activities will be resumed solely by Nycomed Amersham.'

Ultrasound is the ideal tool to examine children of all ages. It is fast, painless, uses no ionizing radiation, and does not require a baby to remain still for long periods. Real-time modes show movement of internal tissues and organs. Advanced ultrasound imaging techniques such as color Doppler, 4D ultrasound, harmonic imaging, and higher resolution, as well as the application of ultrasound contrast agents broaden the potential of ultrasound.
Pediatric [paediatric, Brit.] ultrasound can be used in all body regions and reduce the number of more invasive or radiating examinations that often additionally need sedation or intravenous iodinated contrast agents.

See also Fetal Ultrasound, Reflux Sonography, Ultrasound Safety, Abdominal Ultrasound and Pregnancy Ultrasound.

SONUS Pharmaceuticals, Inc., is engaged in the research and development of ultrasound contrast agents (USCA) and drug delivery systems for use in the diagnosis and treatment of heart disease, cancer and other conditions.
Sonus Pharmaceuticals and OncoGenex Technologies Inc., a privately held biopharmaceutical development company, announced 2008 the signing of a definitive agreement to merge the two companies. The combined company will operate as OncoGenex Pharmaceuticals, Inc.

Ultrasound Contrast Agents:

The third generation ultrasound contrast agents (UCA/USCA) are more echogenic and stable, and are able to enhance the echogenicity of parenchyma on B-mode images. These microbubbles may thus show perfusion, even in such a difficult region as the myocardium.

See also History of Ultrasound Contrast Agents.