Echogenic is a tissue that structures are capable of producing echoes when they are in the path of a sound beam.

See also Echogenicity, and Isoechogenic.

EchoGen® is a fluorocarbon-based (dodecafluoropentane) third generation USCA. EchoGen® consists of microbubbles stabilized with surfactants in a phase shift colloid emulsion (perflenapent). EchoGen® requires no preparation, reconstitution, or refrigeration.
Perflenapent emulsion would represent a significant advance in contrast echocardiography caused by effective and long lasting opacification of the left ventricle and enhanced endocardial border delineation.
The persistence of the contrast effect permits interrogation in multiple echocardiographic views, as well as the visualization and localization of myocardial perfusion deficits at rest by producing a negative contrast effect.
October 12, 2000
Sonus Pharmaceuticals, Inc. announced a strategic decision to refocus the Company on the development of its drug delivery and blood substitute products. At the same time, Sonus has withdrawn the NDA (New Drug Application) and discontinued clinical activity for its ultrasound contrast product, EchoGen®.
August 06, 2001
Sonus Pharmaceuticals, Inc. announced that it has entered into an agreement to sell its ultrasound contrast assets for $6.5 million to Amersham plc. As part of the agreement, Sonus has also assigned to Nycomed its interest in the ultrasound contrast patent license agreement entered into with Chugai Pharmaceutical Co. Ltd. and Molecular Biosystems Inc in January 2001.

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.

The term isoechogenic or isoechoic is used if different tissues have the same echogenicity and are not separate depictable.

Solid regions have internal ultrasound echoes and are classified as echo poor, hypoechoic or hypoechogenic if there are few internal echoes. Hypoechoic structures appear dark in ultrasound imaging, more homogeneous structures are darker than heterogeneous.
Soft atherosclerotic plaque, liver adenoma or FNH appear with a nodular hypoechogenicity. As metastases close the blood vessels they infiltrate, tumor tissues become hypoechogenic after injection of contrast agent. Muscle appears relatively hypoechoic to tendon fibers, also articular hyaline cartilage appears hypoechoic.