Myomap is an investigational ultrasound contrast agent for assessment of myocardial perfusion and has been tested in animals to determine infarct volumes in cases of coronary artery occlusion. The deposit microbubbles of Myomap consist of air filled human serum albumin microcapsule with a thick and rigid shell.

Non-linear imaging is used to detect primary non-linear components of the received echo. Non-linear methods like harmonic imaging and pulse inversion imaging are designed to detect ultrasound contrast agents.

See also Contrast Pulse Sequencing, and Power Modulation.

Perfluorochemicals are used as microbubble filling gases because of their low solubility in blood and high vapor pressure. Various types of perfluorochemical gases like perfluorocarbon, perfluorobutane, perfluoropropane, and perfluorohexane are used to substitute the air in microbubbles to improve the stability and plasma longevity of the agents. Perfluorocarbons are liquids at room temperature but gas at body temperature. The large molecules of perfluorocarbons have slow diffusion and solubility which increase the enhancement time of the ultrasound contrast agent as compared to air.

See also Filling Gas, and PESDA.

The persistence of microbubbles is depended of the shell stability and the density of the gas.
This is defined by the equation:
(R x d)/(DIFS x const_sat)
where R is the bubble radius, d the gas density, DIFS the gas diffusivity and const_sat the saturation constant.
Microbubbles are stabilized with thin coatings of substances such as palmitic acid or by encapsulation in microspheres made with albumin, lipids, or polymers. Low-solubility low-diffusibility gases dramatically improve the persistence. Most recently developed ultrasound contrast agents combine these two approaches to prolong contrast enhancement.
Persistence is also a type of temporal smoothing used in both gray scale and color Doppler imaging. Successive frames are averaged as they are displayed to reduce the variations in the image between frames, hence lowering the temporal resolution of the image.

Different stages of testing drugs in humans for example ultrasound contrast agents, from first application in humans through limited and broad clinical tests, to postmarketing studies. Preclinical trials are the testing in animals.

See also Drug Development and Approval Process USA, Food and Drug Administration, and European Medicines Agency.