Author(s): Olivia Rufai, Margarita Nesbitt, Dr Dean Huang

Hospital: King's College Hospital

Reference: RAD Magazine, 47, 553, 11-12

Excerpt: 

Contrast-enhanced ultrasound (CEUS) has been utilised for a variety of applications, with published guidelines for its appropriate use. Several advantages of CEUS compared with other contrast-enhanced imaging techniques have been shown, including the absence of nephrotoxicity and ionising radiation, real-time assessment of vascularity and excellent spatial resolution. Ultrasound contrast agents (UCA) consist of microbubbles of inert gas stabilised with a lipid, protein shell. The microbubbles are about the size of a red blood cell (1.5-2.5μm) but large enough to prevent their extravasation to the interstitium, thus they are truly intravascular. Contrast-specific software allows visualisation of UCA, taking advantage of the non-linear responses of the micro- bubbles such that contrast agent-only imaging is displayed with subtraction of the background linear tissue signal. Ultrasound contrast agents are safe, with an adverse event rate similar to MRI contrast agents but less than iodinated contrast agents. Non-anaphylactoid adverse events are mild and transient, resolving spontaneously. However, as with all contrast agents, appropriate resuscitation equipment and trained personnel should be readily available at the time of injection. The successful implementation of a CEUS evaluation requires an ultrasound scanner with CEUS imaging software, UCA, IV access and two sets of hands available for injection and performing the scan. Sonographers or nurses may be trained to obtain intravenous access and give UCA to perform CEUS following fulfilment of the training requirement of the individual institution.