Many patient-related and injection-related factors can affect the magnitude and timing of intravenous contrast agent attenuation. MDCT, with its dramatically shorter image acquisition times, permits images with a much better utilization of the peak contrast attenuation. High iodine concentrations of contrast media and newer scanner generations are mutually conditional. The very high iodine flux rates required by cutting-edge angiographic applications can be met by low concentration iodine agents only at very high flow rates resulting in high volumes administered. Sporadic failure, though, is unpreventable at the current stage of development. This is simply due to the fact that the patient’s cardiac output is not known prior to scan initiation in most cases. MDCT is a powerful and continuously evolving technology for noninvasive imaging. CA administration is an integral part of this evolution and needs to be continuously adopted and optimized to take full advantage of this technology. A basic understanding of physiologic and pharmacokinetic principles, as well as an understanding of the effects of injection parameters on vascular and parenchymal enhancement, allows the development of optimized contrast agent delivery protocols for current and future MDCT. Scan timing will only then succeed to acquire images at peak enhancement in the tissue of interest.