Results of a five-year study of 99mTc DMSA renal scintigraphy in children and adolescents following acute pyelonephritis.

BACKGROUND Renal scintigraphy, generally using 99mTc-DMSA, is the accepted reference standard for detection of renal cortical changes. The timing of the test, i.e., whether an acute 99mTc-DMSA scan, a follow-up only or both scans should be performed, however, remains open to discussion. In our study, a six-month follow- up DMSA scan was performed in all the children diagnosed with a first attack of acute pyelonephritis (APN) in two large paediatric clinics of Charles University's 3rd School of Medicine in Prague during a five-year period. All diagnoses were confirmed by a paediatric nephrologist. MATERIAL AND METHODS 382 children (267 girls, 115 boys) aged between 7 months and 19 years were included in the study. For analytical purposes, the patients were divided into 4 age groups: I--less than 1 year of age, II--1-5 years, III--5-10 years, and IV--10-19 years. In all children younger than five years, a micturition cystourethrogram (MCUG) for detection of vesicoureteric reflux (VUR) was performed between one and three months after the APN episode. Static renal scintigraphy, using an HR collimator with parallel holes was performed using a planar Gamma camera MB 9200 (Gamma Budapest) in all children six months after APN, with a complement of pinhole images, SPECT or PSPECT of the kidneys. RESULTS 1. In group I, all four children with positive VUR on MCUG had a pathological DMSA scan, while only two of the 32 patients with negative VUR had a pathological DMSA. 2. In group II, 17 children had VUR on MCUG, six of them with a pathological and 11 with a normal DMSA scan. Most of the 221 children without VUR had a normal DMSA scintigraphy; pathological findings were present in 17 children only. 3. In group III, all children with VUR, but only 5 out of 53 without VUR, had a pathological DMSA scan. 4. Five out of 50 children in group IV had a pathological DMSA. CONCLUSIONS APN occurred most frequently in group II (62.3%, or 238 children) and ranged between 10-15% in the remaining groups. APN was found very frequently in boys less than one year old and showed a marked decrease with increasing age. Among girls, however, APN incidence was observed to increase with age. Pathological renal changes were present in children with, as well as without, VUR. The incidence of pathological DMSA findings six months after APN was relatively low (44/382 patients, or 11.5%). Regular monitoring of these children is very important for detection of renal scarring.