Figure 1:
Simple two-compartment tissue model describes kinetics of transport of albumin-(Gd-DTPA)30 from plasma space into interstitial water of tumor. KPS (in microliters per minute per cubic centimeter of tissue) is the endothelial transfer coefficient denoting the clearance of albumin-(Gd-DTPA)30 from plasma to interstitial water. The rate constant k (per minute), which denotes the fractional rate of reflux of albumin-(Gd-DTPA)30 from interstitial water back to plasma, was not resolvable in the time course of the experiment and was therefore set to zero. The box around the plasma compartment denotes a forcing function representing the monoexponetial disappearance of albumin-(Gd-DTPA)30 from the blood. The kinetics of both compartments taken together reflect the dynamic tissue response to albumin-(Gd-DTPA)30 after intravenous bolus administration.