Intravenous Contrast-Enhanced Bowel Ultrasound

Abstract

In this chapter, we describe the role of ultrasound in case of gastrointestinal disorders. We try to illustrate the historical development and different types of contrast agents and their advantages, limitations, and applications with respect to bowel diseases. Brightness mode (B-Mode) represents an early diagnostic tool for almost all entities of intestinal disease and is able to investigate the localization of intestinal disease, length of the intestinal segments involved, loss of stratification, intestinal obstruction or stenoses, and mesenterial changes as well as associated. B-mode imaging is always a prerequisite for the useful application of Doppler and ultrasound contrast imaging techniques. Combining (Power) Doppler imaging and ultrasound contrast agents improves the visualization of smaller vessels and vessel continuity (i.e., length). Several studies were performed to detect bowel wall hyperemia in inflammatory bowel disease. Contrast harmonic imaging at a low mechanical index is technically feasible for the demonstration of increased intestinal perfusion in inflammatory bowel disease by using high frequency ultrasound transducers. Furthermore, contrast-enhanced power Doppler sonography may help to discriminate the origin of small bowel stenosis in Crohn`s disease. Different studies evaluated the vascularization of the thickened terminal ileum in Crohn`s disease patients using CEUS and compared the clinical activity measured by the Crohn`s disease activity index (CDAI) with the sonographic findings. Using certain perfusion parameters (peak value, time-to-peak, regional blood volume), studies could show differences between inflamed and normal bowel wall vascularity in terms of significant higher peak values and significant higher regional blood volume in the bowel wall of patients with an active episode of Crohn`s disease. Additionally, CEUS can be a useful technique to monitor the activity of Crohn`s disease, to increase the accuracy of color Doppler ultrasound in diagnosis, and followup of patients with Crohn`s disease and to assess disease activity. Fewer studies exist concerning ulcerative colitis, bowel ischemia, graft-versus-host-disease, and appendicitis.