Correlation of computed tomography and nephrography in quantitative comparison of urographic contrast agents

The use of computed tomography (CT) to estimate the differences in radiographic contrast obtainable with different contrast agents is discussed. A CT scanner was calibrated to measure the in vivo iodine concentration, and phantom studies were performed to derive the relationship between iodine concentration and resultant radiographic contrast in the kidneys. The technique is illustrated by a quantitative comparison of the nephrographic phase in dogs with two urographic contrast agents, sodium iothalamate and sodium ioxaglate.