Comparison of direct radionuclide cystography and voiding direct cystography in the detection of vesicoureteral reflux

Evidence-based clinical practice guideline for management of urinary tract infection and primary vesicoureteric reflux

We present updated, evidence-based clinical practice guidelines from the Indian Society of Pediatric Nephrology (ISPN) for the management of urinary tract infection (UTI) and primary vesicoureteric reflux (VUR) in children. These guidelines conform to international standards; Institute of Medicine and AGREE checklists were used to ensure transparency, rigor, and thoroughness in the guideline development. In view of the robust methodology, these guidelines are applicable globally for the management of UTI and VUR. Seventeen recommendations and 18 clinical practice points have been formulated. Some of the key recommendations and practice points are as follows. Urine culture with > 104 colony forming units/mL is considered significant for the diagnosis of UTI in an infant if the clinical suspicion is strong. Urine leukocyte esterase and nitrite can be used as an alternative screening test to urine microscopy in a child with suspected UTI. Acute pyelonephritis can be treated with oral antibiotics in a non-toxic infant for 7-10 days. An acute-phase DMSA scan is not recommended in the evaluation of UTI. Micturating cystourethrography (MCU) is indicated in children with recurrent UTI, abnormal kidney ultrasound, and in patients below 2 years of age with non-E. coli UTI. Dimercaptosuccinic acid scan (DMSA scan) is indicated only in children with recurrent UTI and high-grade (3-5) VUR. Antibiotic prophylaxis is not indicated in children with a normal urinary tract after UTI. Prophylaxis is recommended to prevent UTI in children with bladder bowel dysfunction (BBD) and those with high-grade VUR. In children with VUR, prophylaxis should be stopped if the child is toilet trained, free of BBD, and has not had a UTI in the last 1 year. Surgical intervention in high-grade VUR can be considered for parental preference over antibiotic prophylaxis or in children developing recurrent breakthrough febrile UTIs on antibiotic prophylaxis.

Clinical implications of primary "occult" vesicoureteral reflux in male children

OBJECTIVES

To compare characteristics and outcomes of vesicoureteral reflux (VUR) detected solely on isotopic cystography (IC) ("occult" VUR) with voiding cystourethrography (VCUG)-detected VUR.

MATERIALS AND METHODS

Between 2015 and 2020, we retrospectively enrolled all male children first undergoing VCUG and, if negative, IC in the same session. Kidney injury (KI) was defined by abnormal estimated glomerular filtration rate and/or blood pressure and/or proteinuria.

RESULTS

We enrolled 421 males with a median age of 3 months and a follow-up of 5.3 years. None exhibited KI initially, but 10% of those with VUR developed KI during follow-up. Two hundred and twenty-two patients (52.7%) did not show VUR, 152 (36.1%) had VCUG-diagnosed VUR, and 47 (11.2%) had occult VUR. Therefore, 47/199 patients (23.6%) with VUR had occult VUR. Among these, 34/47 (72.3%) had dilated VUR, and 22/47 (46.8%) exhibited split renal function < 45% and/or scar (scintigraphic damage). Compared to patients with occult VUR, those with VCUG-diagnosed VUR showed a similar prevalence of febrile urinary tract infection (fUTI) before and after VUR diagnostics and KI at the last follow-up but a higher prevalence of dilated VUR, of scintigraphic damage, and underwent surgery more frequently. At multiple logistic regression analysis, patients with VCUG-diagnosed VUR presented an increased risk of fUTI either before or after VUR diagnosis and of KI, while patients with occult VUR presented an increased risk of fUTI before (and among patients with dilated VUR also after) VUR diagnosis and of KI.

CONCLUSION

Occult VUR affects 23.6% of male children with VUR with a non-negligible risk of VUR-associated KI and fUTI. IC could select, among males with recurrent fUTIs and negative VCUG, those requiring surgery for a possible dilated occult VUR.

CLINICAL RELEVANCE STATEMENT

Vesicoureteral reflux may be overlooked in 25% of boys during VCUG, yet they are at risk of fUTIs and KI. In case of recurrent infections post-negative cystourethrography, IC could detect occult reflux, guiding surgical intervention.

[Sensitivity of voiding urosonography as a function of the number of the cyclic bladder fillings]

BACKGROUND

Vesicoureteral reflux (VUR) can occur intermittently. Cyclic testing of VUR (observation of multiple phases of filling and micturition) increases the detection rate of VUR, as has been shown in studies which have generally used a two-cycle test period.

OBJECTIVES

How large is the dependence of the sensitivity in voiding urosonography (VUS) on the number of observed cycles when more than two cycles are observed in a larger number of patients? How many cycles should be observed in order to achieve sufficient sensitivity?

PATIENTS AND METHODS

The study population consisted of 302 patients (225 female, average age 2.5 years [range 1 month-17 years]; 77 male, average age 6 months [range 1 month-2.5 years]) with 607 kidney-ureter units (KUU), examined in a pediatrican practice from 05 January 2016 to 31 December 2019. The examinations were performed by contrast-enhanced color Doppler voiding urosonography using the ultrasound contrast agent SonoVue® (Bracco Imaging, Milan, Italy) for an average of 3.14 cycles and, in the case of undetectable VUR, for an average of 3.5 cycles (range 1-6 cycles).

RESULTS

In all, 118 of 302 patients were found to have VUR. In terms of KUU, 163 of 607 KUU exhibited reflux. VUR occurred intermittently in 32.5% of KUU. Depending on the number of cycles observed, there was a significant increase in sensitivity of the VUS. Using the observation of five cycles as a reference for the sensitivity, the following values are obtained: 1 cycle = 82.2%, 2 cycles = 87.7%, 3 cycles = 96.3%, 4 cycles = 98.8%, 5 cycles = 100%.

CONCLUSIONS

To achieve a sensitivity of 96% in detecting VUR, three cycles must be observed. If less than three cycles are observed, the sensitivity shows a marked decrease.

Lower radiation burden in state of the art fluoroscopic cystography compared to direct isotope cystography in children

INTRODUCTION

Both, fluoroscopic voiding cystourethrography (fVCUG) and direct isotope cystography (DIC) are diagnostic tools commonly used in pediatric urology. Both methods can detect vesicoureteral reflux (VUR) with a high sensitivity. Whilst the possibility to depict anatomical details and important structures as for instance the urethra in boys or the detailed calyceal anatomy are advantages of fVCUG, a lower radiation burden is thought to be the main advantage of DIC. In the last decade, however, a rapid technical evolution has occurred in fluoroscopy by implementing digital grid-controlled, variable rate, pulsed acquisition technique. As documented in literature this led to a substantial decrease in radiation burden conferred during fVCUGs.

OBJECTIVE

To question the common belief that direct isotope cystography confers less radiation burden compared to state of the art fluoroscopic voiding cystography.

STUDY DESIGN

Radiation burden of direct isotope cystography in 92 children and in additional 7 children after an adaption of protocol was compared to radiation burden of fluoroscopic voiding cystourethrography in 51. The examinations were performed according to institutional protocols. For calculation of mean effective radiation dose [mSv] for either method published physical models correcting for age and sex were used. For DIC the model published by Stabin et al., 1998 was applied, for fVCUG two different physical models were used (Schultz et al., 1999, Lee et al., 2009).

RESULTS

The radiation burden conferred by direct isotope cystography was significantly higher as for fluoroscopic voiding cystourethrography. The mean effective radiation dose for direct isotope cystography accounted to 0.23 mSv (± 0.34 m, median 0.085 mSv) compared to 0.015 mSv (± 0.013, median 0.008 mSv, model by Schultz et al.) - 0.024 mSv (± 0.018, median 0.018 mSv, model by Lee et al.) for fluoroscopic voiding cystourethrography. After a protocol adaption to correct for a longer examination time in DIC that was caused by filling until calculated bladder capacity, mean radiation burden accounted to .07 mSv (median 0.07 mSv) and the values were less scattered.

DISCUSSION

As it had to be expected from literature, radiation dose from fVCUG, if modern image acquisition techniques are used, is even less than from DIC. In our protocol, according to nuclear medicine standards, bladders were filled until calculated capacity. This resulted in a longer examination time for the patients with a higher functional capacity, resulting in relatively higher radiation burden. However, also if the protocol is changed or only the patients with relatively fast bladder emptying are considered, radiation burden conferred by DIC is higher (at least × 2.9, comparing the "worst" case for fVCUG with the "best" case for DIC). Absolute radiation burden conferred by either exam is extremely low compared to other medical radiation exposures as well as to environmental radiation. Consequently it is most probably not relevant for the individual childs future risk for cancer or other radiation damage. However, because of repeated investigations with correspondingly higher radiation burden in this patient group the ALARA (as low as reasonably achievable) principle should lead to a optimized use of fVCUG rather than an uncritical use of DIC, given that modern acquisition standards are available and radiation measurement is performed. Also, fVCUG provides more information concerning anatomical details compared to DIC.

CONCLUSION

Contrary to common beliefs, effective radiation dose conferred during fluoroscopic voiding cystourethrography is significantly lower than during direct isotope cystography. The prerequisite for our findings, however, is the use of modern image acquisition tools and an optimized protocol. Both exams confer low radiation doses probably only relevant to children undergoing repeated radiation exposure. Nevertheless, this findings should be considered in indication for either exam in order to reduce the radiation burden to a minimum whilst optimizing the information yield.

The value of direct radionuclide cystography in the detection of vesicoureteral reflux in children with normal voiding cystourethrography

BACKGROUND

Vesicoureteral reflux (VUR) is one of the most important risk factors for urinary tract infection (UTI). Diagnosis and treatment of VUR is important to prevent irreversible complications, such as renal scarring and chronic renal failure. This study was conducted to assess the value of direct radionuclide cystography (DRNC) in the detection of VUR in children with UTI and a normal voiding cystourethrography (VCUG).

METHODS

DRNC was performed in 35 children with a normal VCUG after an episode of febrile UTI who had hydronephrosis or hydroureter, abnormal acute dimercaptosuccinic acid (DMSA) scan results and/or febrile UTI recurrence. This study was conducted in the nephrology department of Mofid Children's Hospital, Tehran (Iran).

RESULTS

The results were statistically analyzed. Among the 70 ureters studied, 33 (49.1 %) were observed to have VUR. Of these, 17 (51.5 %) had mild, 14 (42.4 %) moderate, and 2 (6.1 %) severe reflux. A significant relationship was observed between DRNC results and DMSA renal scan findings (P < 0.05).

CONCLUSIONS

Based on our results, we suggest that DRNC may reveal VUR despite a normal VCUG in children with hydronephrosis, abnormal acute DMSA, and/or recurrent febrile UTI.

Predict the spontaneous resolution of vesicoureteral reflux by direct radionuclide cystography

OBJECTIVES

To evaluate the prognostic value of initial direct radionuclide cystography (DRC) for spontaneous resolution of vesicoureteral reflux (VUR).

METHODS

Fifty-one children with initial diagnosis and 1-6 years' follow-up of VUR by DRC were enrolled in this study. VUR was graded according to the anatomic grading as (1) mild reflux corresponding to tracer just in ureter, (2) moderate reflux with accumulation of activity in a non-dilated collecting system and ureter, and (3) severe reflux equated with a dilated ureter and collecting system. The severity of VUR was also expressed according to the functional classification as (1) transient reflux, which occurred at filling or voiding phase only and (2) persistent reflux, present in both filling and voiding phases.

RESULTS

Twenty-nine of the 51 children had unilateral VUR, and the other 22 had bilateral VUR. In the total of 73 refluxing ureters, there were 12 mild, 49 moderate and 12 severe VUR according to anatomic grading, and 30 transient and 43 persistent VUR according to the functional grading. After follow-up, resolution of VUR was found in 92% (11/12) of mild, 59% (29/49) of moderate and 25% (3/12) of severe VUR (P=.04, mild vs. moderate; P=.003, mild vs. severe). Eighty percent (24/30) of transient and 44% (19/43) of persistent reflux showed spontaneous resolution (P=.003).

CONCLUSIONS

DRC allows anatomic and functional classification of VUR. It is an ideal method for the diagnosis, staging and follow-up of VUR, and provides valuable information to predict the patient's outcome.

Interactive magnetic resonance voiding cystourethrography (iMRVC) for vesicoureteric reflux (VUR) in unsedated infants: a feasibility study

OBJECTIVES

The current reference standard for diagnosing vesicoureteric reflux is the X-ray-based Micturating CystoUrethroGram (MCUG). The aim of this study was to evaluate the feasibility of performing interactive Magnetic Resonance voiding cysto-urethrography (iMRVC) in un-sedated infants.

METHODS

Twelve infants underwent conventional single-cycle MCUG followed by iMRVC. In iMRVC, patients were examined using an in-house developed fluoroscopic pulse sequence, which allows on-the-fly control of image contrast and geometry. A single acquisition was performed during bladder filling, during and after micturition, with interactive control over imaging parameters. Images were assessed for diagnostic quality and presence of VUR.

RESULTS

Every case of reflux identified with MCUG was identified on iMRVC (100% sensitivity). Over 24 renal units, there was 88% concordance (21/24) according to the presence of reflux between the two methods. There were three "false positives" detected by MRI, giving a specificity of 83.3%, PPV of 66.7% and NPV of 100%.

CONCLUSION

iMRVC is a feasible method for evaluating the renal tract in infants without the need for radiation or sedation. A formal evaluation is required to establish its diagnostic potential.

Vesicoureteric reflux: Evaluation by bladder volume graded direct radionuclide cystogram

Aim:

Evaluation of vesicoureteric reflux (VUR) in children by bladder volume graded direct radionuclide cystogram (BVG DRC). This technique allows detection of VUR at different bladder volume grades.

Materials and Methods:

In this prospective study, 33 patients (66 renal units) with suspected vesicoureteric reflux were subjected to a voiding cystourethrogram (VCUG) and BVG DRC. The patients were assessed further with radioisotope renal scans for renal cortical scars.

Results:

Twenty-two patients and 36 renal units were found to have VUR in either of the reflux studies. A VCUG was able to detect 20 units (55.50%) and a BVG DRC was able to detect 35 units (97.2%). A VCUG had a test accuracy of 77.8% and a BVG DRC had a test accuracy of 98.6%. There was a positive correlation between bladder volume grades and scarring on a DMSA scan.

Conclusions:

Like a conventional DRC, BVG DRC is a sensitive and an accurate test. It gives additional information on the reflux phenomenon with respect to bladder filling. The bladder volume graded technique is better than conventional DRC for grading of VUR.

Improvement in vesicoureteral reflux grade on serial imaging predicts resolution

PURPOSE

When children are initially diagnosed with vesicoureteral reflux most undergo a period of antibiotic prophylaxis followed by serial imaging. Although improvement in reflux grade through time presumably predicts eventual resolution, the significance of changing grade through time is unknown. We examined whether improvement in reflux on serial imaging predicts resolution.

MATERIALS AND METHODS

We retrospectively reviewed 1,761 children diagnosed with vesicoureteral reflux, of whom 965 had a minimum of 2 years of followup. We examined initial reflux grade and grade on serial imaging up to 5 years after the original diagnosis. For each child it was determined whether reflux was resolved, eventually resolved or never resolved. Groups were further stratified by clinical characteristics.

RESULTS

Multivariate analysis revealed that male gender (HR 1.33, p = 0.05), age younger than 1 year at diagnosis (HR 1.35, p = 0.004), lower grade at presentation (grade I HR 2.2, grade II HR 1.96, grade III HR 1.33; p <0.001) and unilateral reflux (HR 1.39, p = 0.001) were all independent predictors of reflux resolution. Multivariate analysis also showed that reflux improvement on imaging 1 year after diagnosis (HR 3.14, p <0.0001) and improvement from the previous year at any point during followup (HR 1.8, p = 0.009) were independent predictors of reflux resolution.

CONCLUSIONS

Consistent with previous findings, male gender, lower reflux grade at presentation, age less than 1 year at presentation and unilateral reflux were all predictive of reflux resolution. Our analysis also demonstrated that improvement in reflux grade on imaging study 1 year after diagnosis was predictive of resolution, and that reflux improvement from the previous year at any point during followup was an independent predictor of resolution. This information will prove valuable in clinical counseling and therapeutic decision making.

Vesicoureteral reflux and urinary tract infection: evolving practices and current controversies in pediatric imaging

OBJECTIVE

Pediatric patients with urinary tract infection (UTI) undergo imaging tests to detect vesicoureteral reflux (VUR) in the belief that VUR correlates to risk of renal scarring. This article describes recent evolution and controversies in the management of UTI and VUR.

CONCLUSION

Multitechnique imaging of UTI and VUR is complex and controversial. Evolution in practice patterns is motivated by the desire to rationally minimize unnecessary interventions and radiation exposure. Ongoing evidence-based research is needed to further improve practice guidelines.

Diagnostic approach to reflux in 2007

There is ongoing controversy regarding the association between vesicoureteric reflux (VUR), recurrent urinary tract infections (UTI), and renal damage. Despite this, routine work up for VUR is still recommended after febrile UTI in most children. The present article reviews the indications and imaging modalities available for VUR diagnosis. Alternative newer techniques like MR cystography and voiding urosonography are discussed. The increasing evidence of the role of DMSA scans in managing children with VUR is highlighted.

Comparison of direct radionuclide cystography and voiding cystourethrography in detecting vesicoureteral reflux

BACKGROUND

Fluoroscopic voiding cystourethrography (VCUG) is a widely used imaging test for the diagnosis of vesicoureteral reflux (VUR). However, high gonadal radiation and intermittent imaging are the main disadvantages of VCUG. Direct radionuclide cystography (DRC) has been advocated for the detection of VUR with increased sensitivity and low radiation doses, however, having the disadvantage of providing less anatomical details for urethral evaluation. In this study, DRC has been compared with standard fluoroscopic VCUG for detection of VUR.

METHODS

A total of 41 children (82 kidney ureter units, KUU) aged 1 month-126 months (median, 15 months) were studied sequentially using DRC and VCUG. The indications of VUR studied were urinary tract infection in 29 children, VUR follow up in eight children and antenatal dilatation history in four children.

RESULTS

A total of 18 refluxing ureters were detected by DRC, 22 refluxing ureters by VCUG and 14 refluxing ureters by both methods. The two methods were concordant for the detection and exclusion of VUR in 85% of KUU. VUR was missed by VCUG in four KUU (three severe, one mild) whereas VUR was missed by DRC in eight KUU (four grade I, four grade III).

CONCLUSIONS

There was a good correlation between DRC and VCUG in the evaluation of VUR. DRC provides continuous monitoring and low gonadal radiation exposure. DRC can be used in the diagnosis of VUR as an alternative to VCUG in selected cases.

Correction of vesicoureteral reflux: where do we stand?

PURPOSE OF REVIEW

Newer techniques of molecular biology allow us to gain a better understanding of the molecular mechanism of primary urinary reflux. In recent years, diagnostic tools and treatment options for vesicoureteric reflux have dramatically changed. In this review, we want to focus on genetics, molecular biology, histology, clinical findings, diagnostic tools and newer surgical techniques for the treatment of vesicoureteric reflux published between 2003 and March 2004.

RECENT FINDINGS

Recent findings have demonstrated that the renin-angiotensin-aldosterone system does not seem to be responsible for the development of primary vesicoureteric reflux. Echo-enhanced ultrasound with contrast medium in the bladder, performed by an experienced investigator, could replace the voiding cystourethrogram in follow-up studies of patients treated conservatively for vesicoureteric reflux. The sensitivity and specificity of ultrasound is in the range of 70-100% in some studies compared with the standard voiding cystourethrogram. Endoscopic treatment of vesicoureteric reflux using Defux or Macroplastique has gained more and more popularity, with success rates ranging between 60 and 86%. The surgery is performed on an outpatient basis with minimal morbidity. Long-term results after open operative techniques have demonstrated cure of reflux in over 95% of cases.

SUMMARY

In the coming years, echo-enhanced ultrasound may replace the standard voiding cystourethrogram during follow-up and it may be used as an initial test in females with normal voiding patterns. Endoscopic reflux correction must be judged on the re-treatment rates and long-term success.