Quantitation of differential renal function with Tc-99m MDP

This study was designed to evaluate the usefulness of the bone tracer Tc-99m MDP for quantitative assessment of relative renal function as compared with renal imaging radiotracers used for that purpose. Differential renal function, i.e., the percent contribution each kidney makes to global renal function, was determined prospectively in 15 consecutive patients using Tc-99m MDP and a renal radionuclide tracer, either Tc-99m DTPA or Tc-99m GHA. Differential function was computed in all cases from the early (1-3 minutes) renal uptake of the tracers by region-of-interest analysis of the computer-acquired data. There was a high correlation between values of differential function obtained with Tc-99m MDP and those obtained with Tc-99m DTPA or Tc-99m GHA (r = 0.98, P less than 0.0001). Qualitative assessment of the images revealed equivalent scintigraphic patterns in all patients. It is concluded that the early characteristics of renal handling of Tc-MDP are sufficiently similar to those of Tc-DTPA and Tc-GHA so that accurate estimates of differential renal function are possible with this agent, and that Tc-MDP-determined renal differential most likely reflects differential glomerular filtration rate.