Quantitative SPECT uptake of ^99mTc-dimercaptosuccinic acid by the kidneys in children

The normal range of values for quantitative SPECT of ^99mTc- dimercaptosuccinic acid (DMSA) uptake by the kidneys in children was studied. Methods: Renal functioning volume, percentage of injected dose per cubic centimeter of renal tissue (%ID/cm³) and individual kidney uptake of 270 kidneys performed on 135 children, aged 2 wk-15 y, provided the basic data for this study. The accrual was part of the work-up of children with urinary tract infection where no structural or functional abnormalities of the renal tract could be established. Children were grouped according to age intervals, and a distribution chart was obtained with 2 SD above and below the mean of the values obtained for volume (%ID/cm³) and kidney uptake in each age group. Results: A significant correlation was found between age and functional volume (r = 0.90; 95% confidence interval [CI], 0.88-0.92; P = 0.000), and a significant inverse correlation was found between age and %ID/cm³ (r = -0.86; 95% CI, -0.88 to -0.82; P = 0.000). No statistically significant correlation was found between age and kidney uptake (r = -0.20; 95% CI, -0.32 to -0.09; P = 0.001). Conclusion: It seems that the normal maturational changes in renal function observed in infants and newborns do not affect the kidney uptake of ^99mTc-DMSA. Thus, quantitation of ^99mTc-DMSA uptake by the kidneys can be used to assess changes in the individual renal function over time in this age group.