COMPUTATION OF THE INITIAL DISTRIBUTION OF A DRUG BY REPETITIVE CONVOLUTION WITH A CIRCULATORY TRANSPORT FUNCTION

Hereby we present a widely applicable computational method for the des cription of recirculation and distribution phenomena occuring immediat ely after intravenous injection of a substance. The intravascular conc entration-time course, r, is described as r = c(0) + gr, where the as terisk denotes the convolution operation, co is the concentration-time course during the first passage of the substance at an arterial measu ring site and g is the transport function of the body. if the body tra nsport function is known, then the arterial concentration-time course of a substance can be predicted for different amounts, injection times and elimination rates. The site of interest can be chosen arbitrarily , i.e. the concentration-time course in the arterial circulation suppl ying any organ can be described. This might be of special interest for the optimal design of intravenous injections of contrast media, where initial concentrations at the region of interest determine the succes s of the diagnostic procedure.