Comparison of Tc-99m DMSA Renal Planar Scan and SPECT for Detection of Cortical Defects in Infants with Suspected Acute Pyelonephritis

Objective To compare the detection rate of Tc-99m dimercaptosuccinic acid (DMSA) renal single photon emission computerized tomography (SPECT) with that of planar scan for renal cortical defects in infants under one year of age with suspected acute pyelonephritis. Methods Sixty infants under one year of age who exhibited fever and pyuria were prospectively included in this study. All infants underwent concurrent Tc-99m DMSA renal planar scan and SPECT. Detection rates for cortical defects and the numbers of cortical defects in both kidneys were compared between Tc-99m DMSA planar scan and SPECT. The cortical defects were classified as large and small; the rate of discordant results was compared between subgroups. Results Negative findings by planar scan in 11 infants (11.3%) were modified to positive findings by SPECT. The detection rate of SPECT was significantly higher than that of planar scan (53.3% vs. 35.0%, p < 0.001). The numbers of cortical defects on SPECT were significantly higher than those on planar scan (0.85 +/- 0.97 vs. 0.53 +/- 0.83, p < 0.001). A significantly higher rate of discordant results between the planar scan and SPECT was observed for the small cortical defects compared to the large cortical defects (48.6% vs. 14.3%, p = 0.029). Conclusions Tc-99m DMSA renal SPECT showed a higher detection rate, compared with planar scan, for renal cortical defects in infants with suspected acute pyelonephritis. The study results suggest that, compared with planar scan, Tc-99m DMSA SPECT can detect small cortical defects with greater sensitivity.