IMAGING OF PYELONEPHRITIS

Objective. Accurate diagnosis of pyelonephritis using clinical and lab oratory parameters is often difficult, especially in children. The mai n aims of this prospective study were to compare the value of differen t imaging techniques [renal sonography, cortical scintigraphy with tec hnetium-99m dimercaptosuccinic acid (Tc-99m DMSA) and computed tomogra phy (CT)] in detecting renal involvement in acute urinary tract infect ions and to determine the sensitivity of DMSA scans for permanent rena l scars 6 months later. Materials and methods. Between February 1992 a nd January 1993, 55 children admitted to our pediatric unit with febri le symptomatic urinary tract infections were eligible for analysis. Ul trasonography (US), DMSA scanning and micturating cystourethrography w ere performed in every case. Only 18 children underwent CT. A second D MSA scan was performed in 48 children a mean of 7.5 months after the f irst. Results. US abnormalities were found in 25 children (45 %). The first DMSA scan showed a parenchymal aspect suggestive of pyelonephrit is in 51 patients (93 %). Among the 18 patients studied by CT, 14 had abnormalities. Normal US findings did not rule out renal parenchymal i nvolvement. Scintigraphy appeared to be more sensitive than CT for ren al involvement. The frequency and degree of initial renal parenchymal damage seemed to correlate with vesicoureteral reflux, but the most se vere initial parenchymal defects were not associated with marked clini cal or laboratory manifestations. Repeat DMSA scans, performed on 45 k idneys with abnormalities at the first examination, showed resolution in 19, improvement in 16, persistence in 8 and deterioration in 2. The prevalence of vesicoureteral reflux was not higher in patients with r enal scarring on the second DMSA scan than in patients whose scans sho wed an improvement. Conclusion. DMSA scans should be considered as a r eference in the detection and follow-up of renal scarring associated w ith acute urinary tract infection as this technique is more sensitive than US and CT, the latter being unsuitable because it entails radiati on exposure and sedation of patients.