Contrast Agents used in Ultrasound

Ultrasound contrast agents are gas-filled micro-bubbles which are injected into the blood stream. Micro-bubbles will give increased backscatter signal due to the large acoustic impedance mismatch between the gas-filled bubble and surrounding tissue

Micro-bubble suspension is injected intravenously into the systemic circulation in a small bolus. The micro-bubbles will remain in the systemic circulation for a certain period of time. Ultrasound waves are directed on the area of interest and when the micro-bubbles in the blood flow pass the imaging window they give rise to increased signal. Also, these CM allows detection of blood flow where it would otherwise not be seen.