Doppler sonography in the diagnosis of inflammatory bowel disease

Over the past few years, thanks to its ability to reveal neovascularization and inflammatory hyperemia, Doppler sonography has proved to be a valuable method for the assessment of disease activity in inflammatory bowel disease. Hypervascularization has been detected by Doppler imaging both in splanchnic vessels, in terms of flow volume and velocity, or resistance and pulsatility index on spectral analysis, and in small vessels of the affected bowel wall in terms of vessel density. In particular, power Doppler has been shown to be a highly sensitive method for evaluating the presence of flow in vessels that are poorly imaged by conventional color Doppler, and in detecting internal fistulas complicating Crohn's disease. Recently, the use of ultrasound contrast agents, such as Levovist, has been shown to improve the image quality of color Doppler by increasing the backscattered echoes from the desired regions, thus making it possible to better monitor the response to treatment and discriminate between active inflammatory and fibrotic bowel wall thickness in Crohn's disease. Additionally, Levovist-enhanced power Doppler sonography has proved to be highly sensitive and specific in the detection of inflammatory abdominal masses associated with Crohn's disease. In clinical practice, used in combination with second harmonic imaging and new generations of stable contrast agents, Doppler sonography appears to be a non-invasive and effective diagnostic tool in the diagnosis and follow-up of Crohn's disease and ulcerative colitis.