Dose reduction in pediatric MAG-3 renal scans

Objectives To determine the minimal administered dose required to perform diagnostically acceptable MAG-3 renal scans in children.

Methods Thirty-six consecutive MAG-3 renal scans performed at the Children’s Hospital Boston from July to August 2008 were evaluated. Each patient received 200 μCi/kg (minimum 1mCi; maximum 10mCi) of 99mTc MAG-3 by intravenous injection. Original studies were binomially subsampled to simulate scans with lower administered doses (50%, 30%, 20% and 10% of the original). All studies were analyzed in random order by each of the 4 nuclear medicine physicians blinded to the level of subsampling. Evaluations included split renal function, cortical transit time and overall diagnostic confidence.

Results The percentage of studies deemed clinically acceptable in each category is summarized below with no significant differences found between 50% dose and 100% dose.

Conclusions Based on subjective visual assessment, the administered dose of MAG-3 scan can be lowered to 50% of the current dose scheme or approximately100 μCi/kg. We plan to examine whether lower administered MAG-3 doses can provide diagnostically acceptable studies with noise reduction image processing.