Prevalence of intrarenal reflux in pediatric patients on contrast-enhanced voiding urosonography

How I Do It: Contrast-enhanced US Applications in Children

Contrast-enhanced US (CEUS) allows a detailed assessment of the tissue microvasculature after intravenous injection of contrast material. The use of CEUS also allows opacification of nonvascular hollow organs and fluid compartments after intracavitary instillation of dilute contrast material. This capability is far beyond that of grayscale and Doppler US techniques. The advantages of CEUS include its ease of use, high safety profile, and absence of ionizing radiation, making it an ideal tool for pediatric imaging. In 2016, the U.S. Food and Drug Administration approved CEUS for use in children for characterization of focal liver lesions and diagnosis of vesicoureteral reflux. Because the US contrast agent is distributed throughout the vascular pool, additional off-label imaging studies have focused on a variety of anatomic structures. This review of pediatric CEUS discusses the safety and technical aspects of CEUS, provides practical information on how to perform intravascular and intracavitary examinations, addresses the most common clinical applications of this method, and offers advice regarding the integration of CEUS into pediatric daily clinical practice.

Reduced kidney size and renal function of high-grade vesicoureteral reflux and intrarenal reflux in contrast-enhanced voiding urosonography

BACKGROUND

Vesicoureteral reflux (VUR) is a common pediatric urological condition associated with renal scarring, hypertension, and chronic kidney disease. Contrast-enhanced voiding urosonography (ceVUS) has emerged as a promising technique for diagnosing and evaluating VUR, with intrarenal reflux (IRR) often detected using this method. This study aimed to explore the relationship between different VUR grades and IRR on ceVUS, and assess the impact of VUR and IRR on kidney size and function.

METHODS

We reviewed all ceVUS studies from January 2019 to December 2023 conducted at West China Hospital, Sichuan University. Both video clips and digital images of the ceVUS examinations were recorded. A total of 220 uretero-renal units (URUs) of 110 children (67 males and 43 females) were included in this study.

RESULTS

Among the 220 URUs assessed, 134 were diagnosed with VUR, and 25 exhibited IRR, with IRR exclusively observed in patients with grade II VUR or higher. Upon age and sex matching, the severity of IRR showed a significant positive correlation with high-grade VUR (P < 0.001). Notably, patients with high-grade VUR and IRR displayed reduced kidney size compared to those without VUR or IRR (P < 0.05). Furthermore, patients with high-grade VUR and IRR had reduced DMSA renal function (P = 0.015, P = 0.012, respectively), and patients with high-grade VUR had more DMSA scars (P = 0.027), compared with those without VUR or IRR.

CONCLUSION

Our study highlights that on ceVUS, the IRR degree was associated with the high-grade VUR, along with reductions in kidney size and renal function in patients with high-grade VUR and IRR.

Value of contrast-enhanced sonography in the diagnosis of vesicoureteral reflux

BACKGROUND

Contrast-enhanced ultrasound of the urinary tract and bladder (ceVUS) is an alternative examination method to micturition cysturethrography (MCU/VCUG) for suspected vesicoureteral reflux (VUR) that is increasing in practice. The purpose of this review is to present the current value of ceVUS in the diagnosis.

METHOD

A systematic literature search was performed using the keywords "vesicoureteral reflux", "ceVUS", "VCUG" of the databases MEDLINE and Cochrane Library as well as a review of current German, European, and American guidelines on this topic. In addition, recommendations for action in clinical practice were developed.

CONCLUSION

ceVUS is a quick-to-learn examination method that is equivalent to VCUG for the diagnosis of vesicoureteral reflux and should be used as the diagnostic method of first choice when available given the absence of radiation exposure.

KEY POINTS

· Like VCUG, ceVUS is the diagnostic method of first choice in suspected vesicoureteral reflux and should be used preferentially given the absence of radiation exposure.. · Especially in comparison to the alternative VCUG, ceVUS is a quick-to-learn examination method.. · ceVUS can also be used to diagnose other pathologies of the lower urinary tract..

CITATION FORMAT

· Conen P, Thiemann J, Stredele R et al. Value of contrast-enhanced sonography in the diagnosis of vesicoureteral reflux. Fortschr Röntgenstr 2024; 196: 1022 - 1028.

The Intrarenal Reflux Diagnosed by Contrast-Enhanced Voiding Urosonography (ceVUS): A Reason for the Reclassification of Vesicoureteral Reflux and New Therapeutic Approach?

Vesicoureteral reflux (VUR) is defined as the urine backflow from the urinary bladder to the pyelo-caliceal system. In contrast, intrarenal reflux (IRR) is the backflow of urine from the renal calyces into the tubulointerstitial space. VURs, particularly those associated with IRR can result in reflux nephropathy when accompanied by urinary tract infection (UTI). The prevalence of IRR in patients with diagnosed VUR is 1-11% when using voiding cystourethrography (VCUG), while 11.9-61% when applying the contrast-enhanced voiding urosonography (ceVUS). The presence of IRR diagnosed by VCUG often correlates with parenchymal scars, when diagnosed by a 99mTc dimercaptosuccinic acid scan (DMSA scan), mostly in kidneys with high-grade VURs, and when diagnosed by ceVUS, it correlates with the wide spectrum of parenchymal changes on DMSA scan. The study performed by both ceVUS and DMSA scans showed IRRs associated with non-dilated VURs in 21% of all detected VURs. A significant difference regarding the existence of parenchymal damage was disclosed between the IRR-associated and IRR-non-associated VURs. A higher portion of parenchymal changes existed in the IRR-associated VURs, regardless of the VUR grade. That means that kidneys with IRR-associated VURs represent the high-risk group of VURs, which must be considered in the future classification of VURs. When using ceVUS, 62% of places where IRR was found were still unaffected by parenchymal changes. That was the basis for our recommendation of preventive use of long-term antibiotic prophylaxis until the IRR disappearance, regardless of the VUR grade. We propose a new classification of VURs using the ceVUS method, in which each VUR grade is subdivided based on the presence of an IRR.

[Voiding cystourethrography : Indications, fluoroscopy technique and radiation protection]

BACKGROUND

Voiding cystourethrography continues to be the gold standard in the diagnostics of a wide range of diseases of the urinary tract in children.

MATERIAL AND METHODS

Indications, implementation of voiding cystourethrography in terms of preparation, materials used, dealing with the child and the parents as well as the standardized examination technique are presented. In particular, the technical aspects of fluoroscopy devices and criteria for good image quality are discussed. Case studies are used to illustrate the problems of frequent urological diseases.

DISCUSSION

The three standard examinations for the detection of vesicoureteral reflux (VUR), radionuclide cystography, contrast-enhanced voiding urosonography and voiding cystourethrography are compared. Their potential for detecting VUR and additional urological pathologies is discussed in detail. Furthermore, the optimized examination technique of voiding cystourethrography is presented. The applicability of the current dose reference values of the German Federal Office for Radiation Protection (BfS) in the daily routine is discussed and the feasibility of the dose reference values is explained.