Saccharide-Based Ultrasound Contrast Media: Basic Characteristics and Results of Clinical Trials

Signal intensity in the image is due to the acoustic backscatter behaviour of the body region under investigation (echogenicity); it also depends on the existence of acoustic inhomogeneities in the micrometer range. Echoenhancing agents must, therefore provide a sufficiently large and reproducible number of micrometer-sized acoustic scatterers in the body region of diagnostic interest. Following the pioneering work of Gramiak and Shah in 1968 [1], it was reported by Meltzer and coworkers in 1980 [2] that tiny gaseous bubbles (microbubbles), within specially prepared solutions, create the desired echo-enhancing effect in the blood after injection. All industrial developments known so far from publications are based on gaseous microbubbles [3, 4]. Because of their unique acoustic properties, gaseous bubbles therefore play a similar basic role as contrast agents in ultrasound as that played by iodine in X-ray diagnosis and by gadolinium in magnetic resonance imaging.