Urinary excretion of 99mTc administered as microspheres.

99mTc-albumin microspheres were administered intravenously and urinary radioactivity was determined for various periods up to 25 hours. The average accumulated urinary level was 0.68% of the injected dose at 1 hour and 18.6% at 24 hours. The averaged bladder wall dose was 101.98 mrad (1,019.79 muGy) based on an administered dose of 3 mCi (111 MBq). While the chemical state of the excreted 99mTc was primarily free pertechnetate, some reduced 99mTc species were also excreted. The appearance of 99mTc in the kidneys within the first 15 minutes following injection should not be considered unusual, nor necessarily indicative of right-to-left shunting.