Contrast-enhanced ultrasonography (CEU) is the main strategy for improving US quality. One contrast agent that has been studied in the imaging of inflammation, but which has not yet been human-tested for improvement of US quality in inflammation due to IBD, is microbubbles (MB). MB contrast agents are FDA-approved, and are becoming a common clinical tool for the enhancement of US imaging of cardiovascular hemodynamics around the world. Unlike tissue signal, which is produced by US reflection, the strong signal generated by MB is produced by radial oscillation of the MB in the acoustic field. Current MB used for perfusion imaging have lipid or albumin shells and contain high-molecular weight gases (perfluorocarbons, sulfur hexafluoride), which contribute to their high intravascular stability by preventing outward diffusion of gas. MB are generally 2-4µm in size - smaller than average capillary dimension - and passes unimpeded through the microcirculation. They are also hemodynamically inert, and behave similar to red blood cells in vivo. In animal models the acoustic properties of activated Definity® (Perflutren Lipid Microsphere) injectable suspension, were established at or below a mechanical index of 0.7 (1.8 MHz frequency). In clinical trials, the majority of the patients were imaged at or below a mechanical index of .08.