Contrast Agent Application and Protocols

Abstract

Contrast enhanced MDCT is a powerful and continuously evolving technology for non-invasive imaging of the abdomen. As for contrast media application in general, there is a variety of patient-related and injection-related factors that can affect the magnitude and timing of intravenous contrast agent attenuation for abdominal CT scans. MDCT, with its dramatically shorter image acquisition times, permits images with a much better utilization of the peak contrast attenuation. High iodine flux rates—e.g. required by modern angiographic applications—can be achieved with newly developed high concentration iodine contrast agents. In contrast low concentration iodine agents need to be injected at very high flow rates resulting in high volumes administered to meet these requirements. Sporadic failure, though, is unpreventable at the current stage of development. This is due to the fact that the patient’s cardiac output is not known prior to scan initiation in most cases. Contrast media administration is an integral part of the ongoing evolution of MDCT and needs to be continuously adopted and optimized to take full advantage of this technology. The purpose of this chapter is to give a basic understanding of physiologic and pharmacokinetic principles, as well as an understanding of the effects of injection parameters on vascular and parenchymal enhancement. This will enable the development of optimized contrast agent delivery protocols for current and future MDCT abdominal scans.