Doppler ultrasonography as a predictive tool for permanent kidney damage following acute pyelonephritis: comparison with dimercaptosuccinic acid scintigraphy.

INTRODUCTION: The aim of this study was to investigate power Doppler ultrasonography for diagnosis and prediction of scarring compared with technetium Tc 99m dimercaptosuccinic acid scintigraphy in acute pyelonephritis.

MATERIALS AND METHODS: Sixty-six children, aged 2 months to 6 years old, admitted with clinical and biological signs of their first febrile urinary tract infection were studied. All of the children underwent PDU and technetium Tc 99m dimercaptosuccinic acid scintigraphy within 7 days after diagnosis and repeat scintigraphy at least 6 months later, if results of the first study were abnormal. Scintigraphic and Doppler studies were interpreted and compared.

RESULTS: Dimercaptosuccinic acid scintigraphy demonstrated scar in 7.6% of renal units, 3.1% of patients without reflux and 66.7% of those with high-grade reflux. Kidneys with permanent kidney damage had a mean resistive index (RI) of 0.71 ± 0.06, while the RI value for nonscarred kidneys was 0.66 ± 0.06 (P = .02). The best cutoff point of RI value was 0.715, with a sensitivity of 70%, a specificity of 87.7%, and positive and negative predictive values of 32% and 97%, respectively. These values significantly increased when grey-scale ultrasonography findings were brought into account. Reflux was observed in 19.7% of renal units, which were associated with significantly higher RI values (P = .05).

CONCLUSIONS: Power Doppler ultrasonography with a cutoff value of 0.715 has a reasonable sensitivity and specificity for prediction of renal scarring in young children with febrile urinary tract infection.