Comparison between photofluorography and standard fluoroscopic voiding cystourethrography in evaluating vesicoureteral reflux in children with urinary tract infection.

BACKGROUND: Imaging of the urinary system is considered to be responsible for significant radiation in children.

OBJECTIVES: This study was conducted to measure and compare the radiation dose in spot films with photofluorography voiding cystourethrography (VCUG) in children.

PATIENTS AND METHODS: 111 [222 Kidney Urinary Unit (KUU)] pediatric patients, aged 1 month to 5 years, with symptomatic urinary tract infection were enrolled in the study. Peak tube voltage (kVp), exposure setting (mAs), focus film distance (FFD), film size and DAP (after the exam) were recorded for all patients. To evaluate the validity of the photographs, we calculated sensitivity, specificity, predictive values and agreement between the two methods using the kappa statistic. If the kappa was greater than 0.75, between 0.4-0.75 or less than 0.4, then the agreement was excellent, good or poor, respectively. P values less than 0.05 were statistically significant.

RESULTS: Vesicoureteral reflux (VUR) was detected in 74 KUU (33.3%) in standard films and in 71 (32%) in photographic images. The photographs had no false positives and 3 false negatives. Therefore, the new method had a sensitivity of 96%, a specificity of 100%, a negative predictive value of 98% and a positive predictive value of 100%. The two-method agreement in the VUR diagnosis for grades 1, 4, 5 and the overall grading were excellent (kappa > 0.83); however, for grades 2 and 3, agreement was 80%, which was good (kappa = 0.64).

CONCLUSIONS: Our study suggests that the high validity and excellent agreement of the photofluorography method in the diagnosis and grading of VUR, which is comparable to spot films and represents a 50%-90% reduction in radiation, makes it the preferred method.