Characteristics of SonoVue™

The advances made by ultrasonography in the last decade, in parallel with the development of ultrasound contrast agents, have opened a wide range of potential breakthroughs in the field of ultrasound imaging. SonoVue™ is a new echocontrast agent made of microbubbles stabilized by phospholipids and containing sulphur hexafluoride (SF6), an innocuous gas. The suspension of the microbubbles is stable over the time following reconstitution. The bubble concentration of SonoVue™ is between 100 and 500 million per ml. The mean bubble diameter is 2.5 μm and more than 90% of the bubbles are smaller than 8 μm. Following intravenous injection, the bubble suspension is submitted to pressure increases. SF 6 , a high molecular weight gas with low solubility in water, was selected since laboratory tests showed that it confers to the bubbles a good resistance to pressure changes as those that occur in the left ventricle, in the pulmonary capillaries, or in the coronary circulation. The high bubble concentration, combined with a favorable size distribution profile, provides SonoVue™ with a strong echogenicity. SonoVue™ shows a peak in the backscatter coefficient at about 3 MHz. With regard to the gas contained in the bubbles, its pharmacokinetics have been assessed during a study in human volunteers. Following intravenous administration of 0.3 ml/kg of SonoVue™ (i.e., approximately ten times the imaging dose), the blood level curve showed a distribution half‐life of about 1 minute and an elimination half‐life of about 6 minutes. More than 80% of the administered gas is exhaled via the lungs after 11 minutes. Extensive studies in animals and humans have confirmed the outstanding safety profile of this second generation contrast agent and its capability in providing a clinically useful ultrasound signal enhancement for the evaluation of cardiac function and extracardiac vessel abnormalities. Thanks to the long persistence of SF 6 microbubbles, SonoVue™ is also potentially useful in the assessment of myocardial perfusion, as well as microcirculatory disorders.