Noninvasive measurement of renal function with 99mTc-MAG3 gamma-camera renography based on the one-compartment model.

OBJECTIVE

The aim of this study was to develop a method for measuring renal function with 99mTc-MAG3 gamma-camera renography without blood or urine sampling and evaluate its feasibility.

PATIENTS, MATERIAL AND METHODS: Twelve patients with nephrological disorders underwent 99mTc-MAG3 renography and para-aminohippurate clearance measurement. Plasma clearance of 99mTc-MAG3 (ClMAG) was calculated through early renal uptake of 99mTc-MAG3 after appropriate correction of parameters (background, measured attenuation coefficient of 99mTc, and the actual depth of kidneys measured with computed tomography), and on one-compartment assumption of the kinetics of 99mTc-MAG3. We compared the resultant ClMAG with standard effective renal plasma flow (ERPF), using the para-aminohippurate clearance method and with simulated ClMAG derived from the two-compartment model.

RESULTS

ClMAG calculated by the one-compartment model (283+/-131 ml/min, mean +/- SD) correlated with ERPF (r = 0.94, p <0.001), and was similar to the simulated ClMAG estimated from the two-compartment model in all patients (283+/-139 ml/min).

CONCLUSION

This alternative method, which employs theoretical modeling of the pharmacokinetics of 99mTc-MAG3, may provide easy, noninvasive measurement of individual renal function without blood sampling or in vitro equipment. Further studies should be warranted.