Power Doppler sonography versus Tc-99m DMSA scintigraphy for diagnosing acute pyelonephritis in children: are these two methods comparable?

PURPOSE This study assessed the role of renal power Doppler ultrasonography (PDU) to identify acute pyelonephritis (APN) and to determine whether PDU can replace Tc-99m DMSA renal scintigraphy in the diagnosis of APN in children. METHODS A prospective study was conducted in 40 infants and young children (78 kidneys were evaluated) with a mean age of 25.9 months (range, 1 to 68 months) who were hospitalized with a first episode of high fever and bacteruria, possibly APN. All children were examined by PDU and Tc-99m DMSA within the first 3 days after admission. Patients with congenital abnormalities, hydronephrosis, and urinary reflux were excluded. RESULTS Twenty-seven of the 78 kidneys appeared abnormal on Tc-99m DMSA, and 20 of them were abnormal on PDU. Fifty-one of 78 kidneys were normal on Tc-99m DMSA, and 3 of 51 appeared diseased on PDU. The accuracy of PDU was 87%, sensitivity was 74%, and specificity was 94%. The positive predictive and negative predictive values were both 87%. When considering the numbers of lesions in 27 kidneys with positive Tc-99m DMSA studies (38 lesions), PDU did not disclose 16 lesions (false-negative results). Thus, the sensitivity of PDU for diagnosing lesions of APN decreased to 58%. CONCLUSIONS A positive PDU finding should obviate the use of Tc-99m DMSA in patients thought to have possible APN. However, because of a large number of false-negative results (26%) and underestimation of the number of pyelonephritic lesions (low sensitivity of 58%), PDU cannot replace Tc-99m DMSA in the diagnosis of APN in children.