Estimate Split Renal Function Using ^99mTc-DMSA SPECT/CT in Infants with Antenatally Detected Hydronephrosis

Purpose: Split renal function (SRF) can be estimated using diuretic 99mTc-DTPA renography. However, tracer pooling in the dilated pelvis or calyces may result in an overestimation of the SRF in the affected kidney, especially when planar imaging is used. The aim of the present study is to evaluate the use of 99mTc-DMSA, a cortical binding agent, in the estimation of SRFs in infants with antenatally detected hydronephrosis. We included only infants with high-grade hydronephrosis (Society of Fetal Urology grade III-IV) as the effect of tracer pooling in the dilated calyces and pelvis will be more significant. A comparison between SRFs calculated by planar imaging and 3D SPECT/CT method will be made.

Methods: During January 2008 to December 2018, a total of 22 infants (16 boys and 6 girls, median age: 6.0 months) with antenatally detected high-grade hydronephrosis received 99mTc-DMSA SPECT/CT. An auto-segmentation with SPECT/CT was processed using PMOD software to estimate individualized SRFs (3D method). Wilcoxon signed-rank test was used to compare the SRFs calculated by planar imaging and 3D methods. Correlation analysis was done by Pearson correlation coefficient.

Results: The mean SRFs from planar imaging and 3D method were 52.6%±4.4% and 54.7%±4.9% for the left kidney, and 47.4%±4.4% and 45.3%±4.9% for the right kidney. The Wilcoxon signed-rank test showed no significant differences in SRFs estimated using planar imaging or 3D method. Pearson correlation analysis showed high correlation between the two methods in calculating SRFs (r=0.0904, P<0.001).

Conclusions: This preliminary analysis showed that for estimating SRFs in infants with high grade antenatally detected hydronephrosis, planar 99mTc-DMSA scintigraphy performs as well as the 3D SPECT/CT method.