A theoretical four-compartment model to evaluate separate kidney technetium-99m-MAG3 kinetics in humans

Pharmacokinetic modeling based on compartmentalization has provided a valuable tool to assess the clearance patterns of various glomerular and tubular agents. However, no models have been proposed thus far that combine vascular data and imaging data in order to gain a deeper knowledge on renal pathophysiology, and to obtain more diagnostic information of clinical relevance. To this aim, we propose a four-pool model for the evaluation of separate renal function.

In a group of ten normal volunteers and twenty patients with various renal diseases, we tested the four-pool model based on the identification of the two kidneys as two distinct pools. This approach made it possible to integrate the separate kidney contributions deriving from in vivo imaging data, and allows the researcher to quantitate many parameters specific to each kidney.

The parameters TERR, TERL, MRTR, MRTL, vR, vL, k3R-1, K3L-1 permit the normal from abnormal states of renal function to be differentiated, as well as monolateral from bilateral renal disease to be separated within the abnormal function group.

The proposed approach combines the advantages of plasma clearance methods with those derived by gamma-camera imaging, and makes it possible to quantitate the differential renal function. This feature may be clinically relevant in renal transplant donors, where full knowledge of renal pathophysiology could guide the procedure.