Optimal vascular and parenchymal contrast enhancement: the current state of the art.

A fundamental understanding of early arterial and parenchymal contrast medium (CM) dynamics is the basis for the design of CT scanning and injection protocols for state-of-the-art cardiovascular and body CT applications. Although normal parenchymal enhancement is primarily controlled by the total iodine dose injected per body weight, arterial enhancement is controlled by the iodine flux, the injection duration, and cardiac output. The technical capabilities of modern CT equipment allow and require precise scan timing to synchronize data acquisition with the desired phase of vascular enhancement (for CTA) and parenchymal enhancement (for liver and pancreatic CT). Automated tube current modulation and weight-based injection protocols allow individual optimization of radiation exposure and reduce interindividual variability of CM enhancement.