BIOKINETIC BEHAVIOR OF TECHNETIUM-99M-DMSA IN CHILDREN

After intravenous administration of Tc-99m-DMSA, biokinetic data were collected from studies on 24 children aged from 5 wk to 14.8 yr (15 no rmal and 9 with renal pathology). Methods: Patients were imaged with a gamma camera up to 30 hr postinjection and the absolute activities in the kidneys, liver, spleen, bladder, knees and whole body were estima ted using an attenuation-corrected conjugate counting technique, Renal uptake and elimination rates and urinary excretion of radioactivity w ere also measured. Results: In children with normal renal function, ma ximal kidney uptake was 42.4% +/- 5.4% and was taken up with a half-ti me of 1.0 +/- 0.2 hr. Renal excretion amounted to 18.0% +/- 4.4% at 24 hr and was lowest in children aged less than 1 yr. In children with a bnormal renal function, apart from the expected reduction in renal upt ake there was evidence of wider variations in uptake rate and increase d urinary excretion. Mean uptakes in liver and spleen were approximate ly 5% and 2%, respectively, in all patients and uptake in knees, assum ed to reside in the metaphyseal growth complexes, was 1.4%. Conclusion : In children with normal renal function, there was little evidence of age-dependent biokinetic factors other than reduced urinary excretion and lower uptake in knees in children aged less than 1 yr. The result s therefore suggest that a single biokinetic model may suffice for rad iation dosimetry purposes in normal children irrespective of age.