Study of bolus geometry after intravenous contrast medium injection: dynamic and quantitative measurements (Chronogram) using an X-ray CT device.

An X-ray computed tomographic (CT) scanner was used to measure and image transmission profiles of a single 8 mm thick object slice digitally with a high temporal (up to 20 ms), spatial (1.1 mm), and density (0.5%) resolution. This special digital radiography imaging mode is called a Chronogram. It produces a time-history of measured attenuation values but not a normal anatomical image. After intravenous bolus injection of contrast medium, bolus shape as a function of time and bolus passage times can be imaged. Absolute iodine concentrations in blood vessels and soft tissue can be evaluated at any time in all body regions. The Chronogram has the potential to quantify physiological parameters such as enhancement, passage times, and relative blood flow through pairs of arteries or symmetrically arranged organs and to measure absolute iodine concentrations. As a disadvantage, patient motion can prevent quantitative evaluation. This drawback can, however, be turned into an advantage in that all kinds of motion can be measured, for example, movement and pulsation of the heart.