Contrast microbubbles can be destroyed by intense ultrasound and the scattered signal level can increase abruptly for a short time during microbubble destruction, resulting in an acoustical flash (sudden increase in echogenicity).
Intermittent imaging with high acoustic output utilizes the properties of contrast microbubbles to improve blood-to-tissue image contrast by imaging intermittently at very low frame rates.
The frame rate is usually reduced to about one frame per second, or it is synchronized with cardiac cycles so that enough contrast microbubbles can flow into the imaging site where most microbubbles have been destroyed by the previous acoustic pulse. Because bubbles are destroyed by ultrasound, controlling the delay time between frames produces images whose contrast emphasizes regions with rapid blood flow rate or regions with high or low blood volume.

Phospholipids are a major component of all biological membranes. When placed in water, phospholipids form a bilayer, where the hydrophobic tails line up against each other. This forms a membrane with hydrophilic heads on both sides. This membrane is partially permeable and very flexible.
Phospholipid containing microbubbles are in use as diagnostic ultrasound contrast agents. Phospholipids can be targeted to atheroma and other pathologic components to enhance atherosclerosis imaging. The majority of these echogenic liposomes range in diameter from 0.25 to 5.0 μm.

From Sonus Pharmaceuticals
QW7437 (SonoGen) is a perfluorocarbon-based ultrasound contrast agent under development. This anionically charge-stabilized emulsion, similar to EchoGen, has been designed for echocardiographic examinations with greater safety and efficacy.

Retrolenticular afterglow could occur through diffraction and refraction on interfaces. A circular object may act as a lens to the ultrasound beam, showing an artifact region of increased echogenicity.

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: