Determination of the normal range of furosemide half-clearance times when using Tc-99m MAG3

In radionuclide diuresis renography, furosemide half-clearance times have been established using Tc-99m DTPA but have not been verified when Tc-99m MAG3 is used. One hundred and six consecutive diuretic renograms using Tc-99m MAG3 for the evaluation of unilateral renal abnormalities were assessed. The furosemide half-clearance times of the normal kidneys were all less than 9.8 minutes, with a mean of 3.4 minutes. In 18 patients, the half-clearance times of the normal kidney were artificially prolonged because urine had drained before the administration of the diuretic. The normal furosemide half-clearance time values obtained using Tc-99m MAG3 were found to be similar to those established for Tc-99m DTPA. Prolonged half-clearance times of Tc-99m MAG3 must be confirmed by visual evidence of obstruction.