Cyclic cystography: diagnostic yield in selected pediatric populations

Association between the imaging characteristics of renal abscess and vesicoureteral reflux

INTRODUCTION

Renal abscesses are rare in pediatric populations. We aimed to highlight the differences in the computed tomography (CT) imaging characteristics of renal abscesses in patients with and without vesicoureteral reflux (VUR).

MATERIALS AND METHODS

Thirteen children with renal abscesses were included and categorized into those with and without VUR. Blood and urine culture results were recorded as positive or negative. Imaging characteristics were recorded: with/without subcapsular fluid collection, with/without upper/lower pole involvement, and with single/multiple lesions in kidneys. Fisher's exact test was used for intergroup comparisons of the rate of positive pathogens and imaging characteristics.

RESULTS

Nine patients had VUR (45.9%). Blood and urine culture were positive in two (15.4%) and seven cases (53.8%), respectively. There was no significant difference in the rate of pathogen-positive blood and urine cultures (blood culture positive/negative status with VUR vs. that without VUR = 2/7 vs. 0/4, p > 0.999, urine culture positive/negative status with VUR vs. that without VUR = 4/5 vs. 3/1, p = 0.559). The two groups differed significantly regarding subcapsular fluid collection presence (with/without subcapsular fluid collection with VUR vs. that without VUR = 9/0 vs 1/3, p = 0.014). There was no significant difference in upper/lower pole involvement (with/without involving upper/lower pole with VUR vs. that without VUR = 8/1 vs 2/2, p = 0.203). Patients with VUR were non-significantly more likely to have multiple lesions compared to those without VUR.

CONCLUSIONS

VUR was associated with subcapsular fluid collection and possibly with multiple lesions, indicating the need for prompt detection of and specific treatment for VUR in cases with these findings.

Voiding cystourethrogram: Who gets a cyclic study and does it matter?

BACKGROUND

Voiding cystourethrogram (VCUG) images the urethra and bladder during both bladder filling and emptying, as well as the ureters and kidneys when vesicoureteral reflux (VUR) is present. Given the variation in VCUG technique and reporting, the American Academy of Pediatrics Sections on Urology and Radiology published a joint standardized VCUG protocol in 2016, which included the recommendation of at least 2 voiding cycles to identify intermittent VUR and/or ureteral ectopia.

STUDY DESIGN

VCUG were assessed for adherence to performance of cyclic study. Children who underwent cyclic evaluation were compared to those who underwent a single cycle VCUG. Radiation dosage was also analyzed. Studies performed on patients >18 years of age and those obtained as part of a trauma evaluation were excluded from study.

RESULTS

Two hundred and eighty-four VCUGs were analyzed, 97 (34.2%) were positive for VUR on the initial cycle. Of the remaining 187 studies, 116 (62%) had multiple filling-voiding cycles while in 71 (38%) only a single cycle was performed. One hundred and sixty-one (86.1%) were negative for vesicoureteral reflux. Twenty-six (13.9%) children were diagnosed with VUR after the initial filling-voiding cycle: 6 were diagnosed with grade I, 2 grade II, 11 grade III, 2 grade IV and 5 grade V. Of the 123 total children found to have VUR, 26 (21.2%) were diagnosed after an initial negative cycle. Younger children were significantly more likely to have a cyclic study performed; mean age of patients undergoing a cyclic study was 1.09 ± 2.16 years versus 3.86 ± 4.5 years (p ≤ 0.0001). Categorically, 74.1% of children less than 1 year of age underwent a cyclic study compared to 6.9% of children older than 5 years of age (p ≤ 0.0001). There was no difference based on sex with 49.1% of males and 50.9% of females (p = 0.667) undergoing cyclic evaluation. Children undergoing a cyclic study had lower median radiation dose 2.15 microGy m2 (range 0.09-111) compared to 4.41 (range 1.3-104) [p = 0.01].

DISCUSSION

Vesicoureteral reflux may occur intermittently and cyclic VCUG is thought to enhance the ability to detect reflux. In our cohort, 26 children (9.2%) were only diagnosed after an additional cycle - ie 21.1% of reflux would have been missed had a cyclic study not been performed. The majority of these patients (69.2%, 18 of 26) were found to have dilating, and thus perhaps more clinically significant, reflux. Our study highlights the importance of obtaining as much information as possible and adhering to the standardized VCUG protocol.

CONCLUSION

Younger children are more likely to undergo cyclic VCUG. While most reflux is detected with the initial filling-voiding cycle, 26 (21.2%) patients were diagnosed after an initial negative cycle with the majority being dilating VUR.

Evaluating the accuracy of simplified VCUG in comparison with traditional VCUG for diagnosis of urinary-reflux in children: Radiation dose reduction

INTRODUCTION

Voiding cystourethrogram (VCUG) is an imaging technique for diagnosing urinary-reflux. VCUG requires X-ray exposure, increasing the risk of malignancies induced by ionizing radiation, especially in children. Considering the importance of early diagnosis of urinary-reflux using VCUG to prevent kidney complications and the significance of reducing the radiation dose during this imaging, this study intends to reduce the imaging views of VCUG and evaluate the urinary-reflux, using a reduced number of images.

MATERIAL AND METHODS

Children referred to a University hospital who underwent VCUG participated in this study. The routine VCUG procedure contained five images. Two images of full-bladder and post-void of each patient were considered a simplified procedure and were evaluated by two radiologists to determine reflux and its grade. The sensitivity and specificity of simplified VCUG were determined.

RESULTS

182 patients with a mean age of 5.36±4.95 years old participated in this study. There were 90% and 82% agreement between routine and simplified VCUG results in the left and right kidneys. The simplified VCUG had 87.2% and 100% sensitivity and specificity in detecting the left-side reflux, 83 .9% and 100%, to detect the right-side reflux.

CONCLUSION

The results showed that using two images instead of five can effectively diagnose and grade urinary-reflux. The simplified VCUG had a relatively good and acceptable agreement in comparison to the routine cystourethrogram. It can effectively reduce the patient's radiation dose, especially in patients who need to perform serial bladder imaging for follow-up after operation.

Evaluation of cyclic direct radionuclide cystography findings with DMSA scintigraphy results in children with a prior diagnosis of vesicoureteral reflux

OBJECTIVES

Direct radionuclide cystography (DRC) with cyclic imaging is a sensitive method used for the detection of vesicoureteral reflux (VUR). Radionuclide cystography is generally recommended for follow-up evaluation of VUR. The aim of this study was to evaluate cyclic DRC with DMSA scan results during the follow-up period in children with a prior diagnosis of VUR.

PATIENTS AND METHODS

DRC findings of 85 children with VUR were evaluated together with DMSA findings during follow-up. VUR grade was classified anatomically as grades I, II, and III reflux. Reflux grades of II and III were regarded as high-grade reflux. Reflux was also graded functionally as transient and continuous on the basis of the presence of reflux on either filling or voiding phases (transient) or both phases (continuous) of at least one cycle.

RESULTS

Among 85 children, 32 (38%) exhibited reflux. In five patients, reflux was observed on both sides, and a total of 37 refluxing units (RUs) were evaluated. According to the highest grade attained in either cycle, 31 (84%) units had grade II, five had grade I and one had grade III reflux. Reflux was continuous in 23 (62%) and transient in 14 (38%) RUs. The incidence of an abnormal scan result was higher in continuous reflux group (78%) than in high-grade anatomic reflux group (59%). The addition of a second cycle resulted in the diagnosis of continuous reflux in six (26%) more RUs. DMSA scan findings correlated significantly with functional reflux classification (P<0.05), but not with anatomic reflux classification (P>0.05).

CONCLUSION

Functional classification of VUR into continuous and transient reflux resulted in higher correlation with DMSA scan findings compared with anatomic reflux grading in follow-up patients with VUR. Cyclic imaging contributed to continuous reflux diagnosis. The significance of functional information obtained from cyclic DRC in initial diagnostic workup, management, and follow-up of children with urinary tract infection needs to be determined with further studies.

Effective endoscopic diagnosis and treatment of pediatric occult vesicoureteral reflux with intermediate to long-term follow-up

PURPOSE

Recurrent febrile urinary tract infections (fUTIs) in children with non-diagnostic voiding cystourethrogram (VCUG) are challenging, as misdiagnosis can lead to renal damage and increased morbidity. We compared fUTI rates before and after endoscopic treatment of patients with suspected occult VUR.

METHODS

Between January 2009 and December 2012, children with history of fUTI and non-diagnostic VCUG(s) underwent endoscopic ureteral hydrodistention (HD) and injection of dextranomer hyaluronic acid co-polymer (Dx/HA). fUTI rates before and after intervention were evaluated. Demographics, imaging and endoscopic findings were assessed.

RESULTS

Thirty-four children (mean age 5.4±2.8 years) underwent bilateral Dx/HA injection for occult VUR. Average follow-up was 28.8 months. Seventeen children had renal scarring. Mean ureteral HD grade was 2.2/3. HD grade for ureters associated with renal scarring was significantly (p<0.05) higher (2.6/3) than those without scarring (2.0/3). Mean injected volume was 1.2 mL. Ureters associated with renal scarring (n=21) required significantly (p<0.05) higher volumes (1.4 mL) than those without scarring (n=47; 1.1 mL). Prior to intervention, the fUTI rate was 0.15/patient/month compared to just 0.02 after treatment (p<0.0001).

CONCLUSIONS

Incidence of fUTIs significantly decreased following treatment, supporting the use of Dx/HA injection in carefully selected children when the suspicion for occult VUR is high.

Imaging chronic renal disease and renal transplant in children

At Great Ormond Street Hospital we have the highest number of paediatric renal transplant patients in Europe, taking cases from across the United Kingdom and abroad. Our caseload includes many children with rare complicating medical problems and chronic renal failure related morbidity. This review aims to provide an overview of our experience of imaging children with chronic renal failure and transplants.

Voiding urosonography with ultrasound contrast agents for the diagnosis of vesicoureteric reflux in children. I. Procedure

Voiding urosonography (VUS) encompasses examination of the urinary tract with intravesical administration of US contrast agent (UCA) for diagnosis of vesicoureteric reflux (VUR). The real breakthrough for US examination of VUR came with the availability of stabilized UCAs in the mid-1990s. This article presents a comprehensive review of various procedural aspects of VUS. Different US modalities are available for detecting the echogenic microbubbles: fundamental mode, colour Doppler US, harmonic imaging and dedicated contrast imaging with multiple display options. The reflux is graded (1 to 5) in a similar manner to the system used in voiding cystourethrography (VCUG). The most commonly used UCA for VUS, Levovist, is galactose-based and contains air-filled microbubbles. The recommended concentration is 300 mg/ml at a dose of 5-10%, or less than 5%, of the bladder filling volume when using fundamental or harmonic imaging modes, respectively. There are preliminary reports of VUS using a second-generation UCA, SonoVue. Here the UCA volume is less than 1% of the bladder filling volume. There is no specific contraindication to intravesical administration of UCA. The safety profile of intravesical Levovist is very high with no reports of side effects over a decade of use in VUS.

Voiding urosonography with US contrast agents for the diagnosis of vesicoureteric reflux in children. II. Comparison with radiological examinations

Studies comparing voiding urosonography (VUS) with voiding cystourethrography (VCUG) and direct radionuclide cystography (DRNC) were analyzed and detailed tables demonstrating the diagnostic values and grading of vesicoureteric reflux (VUR) are presented. Comparative studies of DRNC were too few and did not allow definite conclusions. Using VCUG as the reference, the results of VUS were as follows: sensitivity 57-100%, specificity 85-100%, positive/negative predictive values 58-100%/87-100%, respectively, and diagnostic accuracy 78-96%. With the exception of two studies the diagnostic accuracy reported was 90% and above. In 19% of pelviureteric units (PUUs) the diagnosis was made only by VUS and in 10% only by VCUG. Thus in 9% of PUUs more refluxes were detected using VUS. In 73.6% the reflux grades were concordant in VUS and VCUG. Reflux grade was found to be higher with VUS than with VCUG in 19.6% of PUUs. In 71.2% of PUUs with grade I reflux on VCUG, the reflux was found to be grade II and higher on VUS. The common selection criteria for VUS as the primary examination for VUR currently include (a) follow-up studies, (b) first examination for VUR in girls, and (c) screening high-risk patients.

Recent advances in pediatric uroradiology

Pediatric Urology is a surgical subspecialty that is very dependent upon radiographic imaging as the majority of the genitourinary (GU) tract is internally located. Technological advances in various imaging modalities (e.g. ultrasonography, nuclear medicine, CT and MRI) have aided in our ability to visualize and evaluate the functionality of the GU tract, enabling the diagnosis of various disease processes that affect the genitourinary system. Collectively the advances in uro-radiology have improved our understanding of the natural history of many conditions that involve the GU tract. As a result of these newer imaging modalities, some of the more traditional techniques have assumed a limited role in the diagnostic evaluation of the pediatric GU patient (e.g. intravenous urography).The purpose of this article is to review the advances in radiographic imaging, in particular the cross-sectional imaging modalities and discuss their utility (appropriate indications and application) in Pediatric Urology, so that the reader can maximize the diagnostic yield of these studies. For a thorough review of any of the imaging modalities discussed in this article and their utility in the practice of pediatric urology, I would direct the readers to articles in the radiological literature that are specific to that technology. Besides the obvious technological advances in imaging modalities, this review also discusses the attention to radiation safety for the pediatric patient that every physician who orders a diagnostic imaging study in a child should be aware of.

Voiding urosonography as first step in the diagnosis of vesicoureteral reflux in children: a clinical experience

BACKGROUND

Contrast-enhanced voiding urosonography (VUS) is becoming more widely used for the diagnosis of vesicoureteric reflux (VUR), but until now its use has only been accepted for first diagnosis in females and in the follow-up of children, including boys, who have already undergone voiding cystourethrography (VCUG).

OBJECTIVE

To describe our 6-year experience with VUS used as a first step in the diagnosis of VUR.

MATERIALS AND METHODS

A total of 610 children (334 boys, 276 girls; mean age 22 months), underwent VUS as the first step in the diagnosis of VUR. In selected children, VCUG was also performed.

RESULTS

VUR was detected in 199 of 610 VUS examinations, and 265 refluxing kidney-ureter units were found. Children with VUR underwent antibiotic prophylaxis or surgery. Children without VUR underwent clinical follow-up. Just 60 children underwent VCUG. The criteria for VCUG were: high-grade VUR after consultation with a urologist, onset of urinary tract infection while receiving prophylaxis, nondiagnostic VUS, and other malformations with or without clinical signs.

CONCLUSION

Our experience suggests that we can use VUS as the first step in the diagnosis of VUR in children, boys and girls, with a significant reduction in radiation exposure.

Patient dose reduction during voiding cystourethrography

Voiding cystourethrography (VCUG) is a commonly performed examination in a pediatric uroradiology practice. This article contains suggestions on how the radiation dose to a child from VCUG can be made "as low as reasonably achievable" (ALARA). The pediatric radiologist should consider the appropriateness of the clinical indication before performing VCUG and utilize radiation exposure techniques and parameters during VCUG to reduce radiation exposure to a child. The medical physicist and fluoroscope manufacturer can also work together to optimize a pulsed-fluoroscopy unit and further reduce the radiation exposure. Laboratory and clinical research is necessary to investigate methods that reduce radiation exposures during VCUG, and current research is presented here.

Positron emission tomography: clinical applications in oncology. Part 2

This review continues from a previous review on this topic, which was published in the December issue. In that review, the role of positron emission tomography in lung cancer, lymphoma, breast cancer, head and neck cancer, gastroesophageal cancer, colorectal cancer, malignant melanoma, bone tumors and ovarian cancer was discussed. In this review, the role of positron emission tomography in other malignancies, such as gynecological malignancies other than ovary, pancreatic cancer, hepatocellular cancer, gastrointestinal tumors, urological malignancies, neuroendocrine tumors, adrenocortical tumors, soft-tissue sarcomas, pituitary and brain tumors, is discussed.

Conventional imaging in paediatric uroradiology

OBJECTIVE

To briefly describe basic conventional imaging in paediatric uroradiology.

METHOD

The state of the art performance of standard imaging techniques (intravenous urography (IVU), voiding cystourethrography (VCU), and ultrasound (US)) is described, with emphasis on technical aspects, indications, and patient preparation such as adequate hydration. Only basic applications as used in routine clinical work are included.

RESULT AND CONCLUSION

Conventional imaging methods are irreplaceable. They cover the majority of daily clinical routine queries, with consecutive indication of more sophisticated modalities in those patients who need additional imaging for establishing the final diagnosis or outlining therapeutic options.

Vesicoureteral reflux grading in contrast-enhanced voiding urosonography

INTRODUCTION AND OBJECTIVE

The sonographic diagnosis of vesicoureteral reflux (VUR) with contrast-enhanced voiding urosonography (VUS) is gradually increasing. With the introduction of VUS as part of the routine diagnostic imaging modalities for reflux significant reduction in the number of voiding cystourethrographies (VCUG) was possible. Like in VCUG grading of reflux in VUS is becoming more and more relevant. The aim of this study was to find out if there are any sonomorphologic and sonomorphometric parameters that would correlate with reflux grading in VCUG. Furthermore, a reflux grading system for VUS is proposed and the correlation of this grading system tested with the one of VCUG.

PATIENTS AND METHODS

In one examination session a total of 186 children underwent both VUS and VCUG of whom 89 had VUR in at least one and the same kidney-ureter-unit (KUU) in both diagnostic imagings. The VUS was conducted with intravesical administration of ultrasound (US) contrast medium (Levovist). Ureteral and pelvicalyceal dilatations before administration of US contrast medium and during reflux were documented. Renal pelvic diameter was measured. The density of microbubbles in the renal pelves was scored on a scale of 1-3 (low to high). A grading system for reflux in VUS was set up similar to the international reflux grading system for VCUG with the addition of one more differentiation parameter, namely whether the reflux was primarily in a dilated or non-dilated urinary tract. Reflux grades in VUS were compared with those in VCUG.

RESULTS

None of the sonomorphologic and sonomorphometric parameters demonstrated any clear cut finding that would simplify reflux grading in VUS. In 59/95 (62%) KUUs the reflux grades were the same in both examinations. In 10/95 (11%) and 26/95 (27%) KUUs, the reflux was graded lower or higher, respectively, in VUS than in VCUG. Fifty-seven percent were in a primarily dilated system and the remaining 43% in a non-dilated one. Seventy percent of KUUs diagnosed as having grade I reflux in VCUG, showed as grade 2 on VUS.

CONCLUSIONS

A reflux grading system similar to the one used in VCUG can be applied in VUS. Adding the parameter reflux into a primarily dilated or non-dilated ureter and/or pelvicalyceal system may bring in a further dimension to the reflux grading in VUS. Most of the refluxes labelled as grade I in VCUG are actually grade II or higher.

Cyclic voiding urosonography for detecting vesicoureteric reflux in renal transplant recipients

BACKGROUND

The clinical significance of vesicoureteric reflux (VUR) in renal transplant recipients remains controversial. Voiding urosonography (VUS), a new modality for detecting VUR, can be used in these patients. The sensitivity of X-ray and radionuclide cystography for detecting VUR may be improved with cyclic procedures. The aim of our study was to evaluate whether cyclic VUS is superior to the single-cycle procedure.

METHODS

Cyclic VUS was performed in 27 renal transplant recipients. Eight were children or adolescents and the remaining 19 recipients were adults. VUS was performed according to accepted guidelines. After the first micturition, the catheter was left in place and the entire procedure was repeated under the same conditions.

RESULTS

Both initial cycle and cyclic VUS detected 17 out of 27 (63%) VURs in the same patients. The sensitivity was not improved by cyclic VUS. However, there were differences between the initial cycle and cyclic VUS (P=0.028) when comparing the number of negative results and the grades of VURs detected. This difference was even more pronounced when analysing only positive results. In the initial cycle, five out of 17 (29%) VURs were grade III, compared with 10 out of 17 (59%) grade III VURs in the same patients using the cyclic procedure (P=0.008).

CONCLUSIONS

Cyclic VUS did not improve the detection sensitivity for VUR in our study. However, given that VUR grade may be important for the management of renal transplant recipients, the use of cyclic VUS may provide a useful diagnostic tool for these patients.

Contrast-enhanced gray-scale and color Doppler voiding urosonography versus voiding cystourethrography in the diagnosis and grading of vesicoureteral reflux

PURPOSE

The purpose of this study was to compare contrast-enhanced gray-scale voiding urosonography (CE-VUS) and contrast-enhanced color Doppler voiding urosonography (CE-CDVUS) with voiding cystourethrography (VCUG) to verify whether the use of color Doppler imaging improves the diagnosis and grading of vesicoureteral reflux (VUR).

METHODS

In 74 patients, CE-VUS and CE-CDVUS were compared with VCUG, which was used as the gold standard. SHU 508 A (Levovist) was used as the echo-enhancing contrast agent. VUR was diagnosed if hyperechoic dots or color signals were visualized in the ureter on sonograms. VUR grading was based on morphologic and dynamic findings on CE-VUS and morphologic and color findings on CE-CDVUS. VCUG was performed conventionally, and grading by VCUG was in accordance with the international system of radiographic VUR grading. Patients who voided during 1 examination only (either CE-VUS and CE-CDVUS or VCUG) were excluded from the study. Agreement between the results of CE-VUS and VCUG and between those of CE-CDVUS and VCUG in diagnosing VUR was calculated by kappa statistics. CE-VUS and CE-CDVUS were compared for diagnostic accuracy by the McNemar test.

RESULTS

The agreement between CE-VUS and VCUG in predicting VUR was 90% (kappa score, 0.77; p < 0.001). The agreement between CE-CDVUS and VCUG was 96% (kappa score, 0.91; p < 0.001). CE-CDVUS showed a significantly higher diagnostic accuracy than did CE-VUS (96% versus 90% of cases correctly classified; McNemar chi2 = 4; p < 0.05). This was mainly related to the lower number of false-negative results for grade I and grade II VUR when CE-CDVUS was used.

CONCLUSIONS

The use of color Doppler imaging significantly improves the accuracy of contrast voiding urosonography in the detection and grading of VUR.

Vesicoureteral reflux and urinary tract infections

Urinary tract infection is a common problem in children. The combination of vesico-ureteric reflux (VUR) and urinary tract infection may predispose children to pyelonephritis and subsequent complications. This review outlines the modifications suggested in the recent literature in the protocol for investigations and diagnosing VUR. Recent interest has been expressed in studying certain molecular markers to measure non-invasively renal damage in children with VUR. Long term results of comparative trials between medical and surgical management have been published recently.