Gallbladder activity appearing 6 minutes after the intravenous injection of Tc99m MAG3 simulating a picture of obstructive uropathy of the right kidney.

Two cases of Tc-99m MAG3 renograms performed on the same day are presented. Both of them show considerable liver activity, which is a known drawback for MAG3 by distribution. In the first case, gallbladder activity appeared after 6 minutes, at the same time when tubular drainage and caliceal activity started to show in both kidneys. The gallbladder activity was superimposed over the upper calyces of the right kidney and simulated an obstructive pattern in the time-activity curves. This early gallbladder activity after intravenous injection of Tc-99m MAG3 has not been previously reported. The second case is presented for the purpose of confirming that nothing in the preparation of the kit contributed to this phenomenon.