Mathematical modeling of MC1RL-800 uptake in the body. A) Graphical representation of the multi-compartment model used in this study. The targeted probe injected into the blood stream diffuses to all tissues in the mouse (NS Tissue), preferentially accumulating in the positive tumor in a specific and non-specific manner (Tumor SB and Tumor NSB). Targeted probe also accumulates in the kidney in a specific and non-specific way (Kidney SB and Kidney NSB), and is filtered into the bladder. B) Multi-compartmental model simulations of the pharmacokinetic distribution of probe over time at a range of dosages. On the left, the ex vivo imaging data for an injection of 3 nmol/kg were used to determine the model parameters with the best fit, the simulation (lines) overlay the data (points). In the middle and right are simulations of lower 1 nmol/kg and higher (10 nmol/kg) injected doses, respectively.