Which are Risk Factors developing Renal Cortical Defects on 99 mTc - DMSA Scintigraphy in Children with Acute Urinary Tract Infections?

ABSTRACT

PURPOSE: To determine (1) the relationship between the cortical defects seen on 99 mTc-DMSA renal scans and age, and (2) the presence and degree of vesicoureteral reflux, and then to depict the risk factors for cortical defects in children with acute urinary tract infection (UTI). Furthermore, to assess the diagnostic value of VCUG in predicting a defect on 99 mTc-DMSA renal scans. MATERIALS AND METHODS: We studied 134 kidneys in 67 children aged 15 days-10 years (M:F=39:28) in whom symptomatic UTI was present. In all these children, both DMSA renal scans and voiding cystourethrography (VCUG) were performed. Scanning took place within 7 days of diagnosis and VCUG was performed after one month of diagnosis. Scintigraphic findings were graded according to the extent and number of cortical defects. We evaluated the relationships between the cortical defects seen on DMSA scans and age, and the grade of vesicoureteral reflux. The diagnostic value of VCUG in predicting cortical defects was analysed. Results: The prevalence of cortical defects was greater in patients older than two years (38/54, 70%) than in those aged less than two (38/80, 48%). The frequency of cortical defects was related to vesicoureteral reflux (p or =2yrs) at the time of acute UTI, and high grade of vesicoureteral reflux. The specificity of VCUG in predicting cortical defects is relatively high but the sensitivitiy is low, and a significant proportion of cortical defects therefore occurred in the absence of vesicoureteral reflux.