New Quantitative Parameters for Evaluating Radionuclide Cystography and Their Value in Understanding the Physiology of Reflux

Abstract

In this descriptive study of radionuclide cystography, timeactivity curves were generated from renal pelves with reflux and evaluated to reveal the physiology of the reflux. The generated new parameters were also evaluated for any correlation with the frequency of urinary tract infections and renal scarring. Methods: Thirty-two children with reflux to the renal pelvis (36 refluxing units) were included. Regions of interest were drawn on the pelves and bladder, and time-activity curves were generated. The first reflux phase, the bladder volume at first reflux, and the bladder volume at maximal reflux were defined, and reflux percentages were calculated. Dimercaptosuccinic acid (DMSA) scintigraphy findings and urinary tract infections were used for correlation. Results: New curves from the renal pelvis during bladder filling and bladder emptying were generated and their patterns classified. Episodic reflux to the pelvis was observed on time-activity curves, which demonstrated 4 different emptying patterns during voiding. These patterns were described in detail. Visually, residual activity was present in the renal pelves in 58.8% of patients. The mean number of urinary tract infections per year was 1.07 (range, 0-4; SD, 0.88). The DMSA findings were normal in 57.1% of the patients. Conclusion: We obtained and categorized some new time-activity curve patterns from renal pelves with reflux on radionuclide cystography. Discussing these patterns may help physicians understand the physiology of the reflux and the relationship between infections and reflux. Vesi coureteral reflux (VUR) is a predisposing factor for urinary tract infection (1), and up to 20%240% of patients with urinary tract infection have been shown to have reflux (2-4). The causes of renal scarring are multifactorial, and VUR has been declared to be one of the main risk factors (5). Early diagnosis of VUR and urinary tract infection is necessary to decrease renal scarring (3). VUR may result in hypertension and end-stage renal disease (3,6,7). The correlation between renal scarring and VUR has been shown to vary between 23% and 75% and is higher in patients with a high grade of VUR (8-11). The prevalence of renal damage is higher in patients with severe reflux (7,12,13). Therefore, children with high grades of VUR must be carefully managed, treated, and followed up to achieve a better outcome in adulthood (3).Radionuclide cystography, the preferred procedure for the follow-up of patients with VUR, allows continuous acquisitions and exposes patients to less radiation than does voiding cystourethrography (14).Some information that can be obtained from radionuclide cystography has been shown to correlate with prognosis. In one study, urinary bladder volume and pressure at reflux were prognostic for the resolution of reflux (13); in another, reflux at low bladder volumes was associated with increased renal scarring (7). The ability to predict the prognosis for a particular patient at the time of diagnosis may lead to better treatment decisions and follow-up...