Noninvasive CT determination of arterial blood concentration of meglumine iothalamate.

A quantity that often must be determined in physiological imaging studies is the blood concentration of the tracer over time. This is usually performed by direct arterial or venous blood sampling. We studied the relationship between the concentration of meglumine iothalamate in arterial blood and values determined from voxels containing large blood vessels in a series of CT images at the same location over time. After correction for volume averaging based on a single venous blood sample, there was an excellent correlation between the two blood curves. Differences between the curves were shown to be inconsequential by a simulation of transcapillary transport determinations. We thus conclude that determination of plasma concentration from CT images is a reliable technique for CT transcapillary transport studies.