Correlation of renal ultrasonographic findings with inflammatory volume from dimercaptosuccinic acid renal scans in children with acute pyelonephritis

Purpose: We correlated abnormal findings on renal ultrasonography (US) and inflammatory volume (Volume) on (99m)technetium dimercaptosuccinic acid renal single photon emission computerized tomography (DMSA) in children with acute pyelonephritis (APN) with renal scars. Materials and Methods: A total of 31 males and 14 females (9 days to 9.8 years old) who fulfilled diagnostic criteria for APN and who underwent initial DMSA between January 1995 and July 2002 and followup DMSA at least 6 months later were enrolled in the study. APN was diagnosed by initial DMSA, and placement in the scar or scar-free group was determined by followup DMSA. Photopenic areas on initial DMSA were calculated as Volume, and were compared to US findings. Results: Ultrasound demonstrated 35 abnormal kidneys (38.9%) among these children with APN. Significant differences in age, Volume (11.19 +/- 2.52 ml vs 3.02 +/- 0.75 ml, p <0.005), C-reactive protein (CRP) and photopenic lesion on initial DMSA were found between children with abnormal and normal US. Of 65 children with initial APN foci 33 (50.8%) recovered, and the others had development of scars. The sensitivity of US for detecting APN (identified by DMSA scan) was 49.2%, and the specificity was 88% (OR 7.1, 95% Cl 2.18 to 24.41). The sensitivity of US for predicting renal scarring was 59.4%, and the specificity was 60.6% (OR 2.3, 95% Cl 0.82 to 7.65). Patients with abnormal US findings and high serum CRP (greater than 70 mg/l) had a large Volume (10.96 +/- 3.05 ml) and a 76.2% chance of being in the scar group. Conclusions: US findings are significantly correlated to Volume in APN. Along with a high level of CRP, US is helpful in predicting development of renal scarring.