Three-dimensional ultrasonography-based virtual cystoscopy of the pediatric urinary bladder: a preliminary report on feasibility and potential value

Vesicoureteral refux detection in children: a comparison of the midline-to-orifice distance measurement by ultrasound and voiding urosonography

BACKGROUND

Due to the questionable clinical role of vesicoureteral reflux (VUR) and the search for noninvasive, radiation-free procedures sufficiently reliable to detect VUR, we compared the correlation between the midline-to-orifice distance (MOD) measured by ultrasonography (US) and echo-enhanced voiding urosonography (VUS) for detecting VUR in children. The aim of the study was to determine whether measuring MOD by US could be a reliable predictor of VUR in children.

METHODS

A total of 116 children, aged 0.25-84 months, with 232 potentially refluxing units were investigated simultaneously by measuring the MOD and performing VUS. Indications for cystography were urinary tract infection and follow-up of a previously detected VUR. VUS was performed after the MOD measurement. The results were analyzed with VUS as the reference method.

RESULTS

The MOD was significantly larger in VUR grade III (10.7 mm; p = 0.003) and VUR grade II (9.9 mm; p = 0.001) refluxing units than in non-refluxing units (7.8 mm), even when controlling for the estimated volume/expected maximal capacity (Vest/Vmax) ratio. A MOD cutoff value of 7.4 mm was chosen as a predictor of either the presence or absence of VUR; the sensitivity and specificity of this cutoff measurement for VUR detection were found to be 89 and 24%, respectively.

CONCLUSIONS

Despite the statistically significant difference between the MOD of refluxing versus non-refluxing units identified in our study, the MOD measurement needs further evaluation to determine its potential value as a diagnostic tool for the detection of VUR.

A case-based approach to UTI imaging – making sense of the guidelines

Urinary tract infections (UTIs) are common amongst children and invariably result in imaging tests to look for correctable causes that may predispose the child to infection. The objective of imaging is to identify those children at risk of long-term renal damage. The ideal imaging algorithm is extensively debated in the literature owing to the lack of evidence-based data, evolving theories on the pathophysiology of UTI and vesicoureteric reflux (VUR). The present article provides a case-based approach to the imaging of UTIs and proposes guidelines relevant to the South African setting.

[Imaging in pediatric urology]

BACKGROUND

For many years, sonography and the intravenous pyelogram (IVP) were the most important examination methods for the evaluation of the urinary tract in children. Both methods have their pros and cons: sonography provides ideal visualization of normal kidneys and the evaluation of the pelvicalyceal system. For detection or exclusion of renal scarring, however, this method is not well suited. It provides no information regarding kidney function.

METHODS

With an IVP, it is possible to evaluate urinary excretion and, thus, indirectly assess kidney function. As this examination method involves radiation exposure and the necessity of a contrast agent, it should be avoided in the examination of children. The CT is an excellent examination method that can diagnose nearly all urological diseases in children or answer urological questions; however, a CT scan applies the highest radiation dose of all discussed methods. For this reason, examination via MRI is of increasing importance in uroradiology. Initially only the T2 sequences for the visualization of the urinary tract in children were applied.

CONCLUSION

The current technical developments as well as the use of the contrast agent gadolinium and the antidiuretic agent furosemide allow an all-in-one evaluation of the kidneys and urinary tract.

Editorial review: pediatric 3D ultrasound

Three-dimensional ultrasound is an established diagnostic imaging technique in many specialties. However, in neonates, infants and children three-dimensional ultrasound still is underutilized, partially due to time constraints for post-processing and restricted availability, of devices as well as dedicated pediatric transducers. Also reimbursement issues still need to be addressed. This editorial review presents more or less established pediatric three-dimensional ultrasound applications with proven diagnostic benefit as well as potential future applications of three-dimensional/four-dimensional ultrasound in infants and children, aiming at enhancing research and promoting practical use of three-dimensional ultrasound in relevant pediatric conditions. Particularly, applications in neonatal neurosonography, ultrasound of the urogenital tract as well as some other small part and miscellaneous queries are highlighted. Additional other potential and future indications are discussed briefly, also mentioning restrictions and potential future developments. In summary, three-dimensional ultrasound holds some potential to widen sonographic diagnostic capabilities throughout childhood and hopefully will be increasingly investigated and introduced into clinical practice provided respective equipment and pediatric three-dimensional/four-dimensional ultrasound transducers become available.

Endoscopic treatment of vesicoureteral reflux using dextranomer/hyaluronic acid copolymer in children: results of postoperative follow-up with real-time 3D sonography

OBJECTIVES

We evaluated whether real-time 3D ultrasound (4D-US) together with clinical evaluation is an alternative to voiding cystourethrography (VCUG) after endoscopic treatment of vesicoureteral reflux (VUR) in children at postoperative follow-up.

MATERIAL AND METHODS

We reviewed 178 children who underwent endoscopic therapy with dextranomer/hyaluronic acid copolymer in grade II or III VUR between 2002 and 2005. 4D-US was performed in all patients 1 day and 3, 9 and 18 months after endoscopic therapy. Only children with postoperative urinary tract infections (UTIs) and/or nonorthotopic position of the bulking agent were referred for VCUG.

RESULTS

In 93% of the ureteral units, the depot could be detected in the orthotopic position after 3, 9 and 18 months. None of these children developed UTIs in the postoperative follow-up. Twelve children demonstrated a shifting of the depot, indicating a possible therapy failure. Eight of these 12 patients (66.7%) presented a positive VCUG, and 50% of them sustained UTIs.

CONCLUSIONS

4D-US seems to be a sufficient protocol in the follow-up of children after endoscopic treatment of low-grade VUR. VCUG should be performed in cases of a shifted position of the depot; invasive investigations are unnecessary in asymptomatic children with orthotopic bulk.

Volume US of the urinary tract in pediatric patients-a pilot study

Three-dimensional ultrasonography (3DUS) adds functionality to two-dimensional ultrasonography (2DUS) by allowing examiners to explore volume datasets using multiplanar or rendering methods already familiar to radiologists. In this pilot study, 30 patients referred for ultrasound examination of the urinary tract were examined by 3DUS. Three abnormalities initially not detected by 2DUS were seen: bilateral bladder diverticulae, urachal remnant and bilateral accessory renal arteries. Rendered images of the bladder trigone were feasible in the majority of patients. Potential applications of this technology in pediatric uroradiology and technical pitfalls are illustrated.

Potential role of 3DUS in infants and children

The objective of this review is to discuss basic technical aspects as well as potential pediatric applications of three-dimensional ultrasound (3DUS). Different 3DUS-techniques are already commercially available. Most commonly, a transducer-integrated motor drives a scan-head to acquire a volumetric dataset, which is then reconstructed and viewed using various post-processing techniques. It has been proved feasible to apply 3DUS with pediatric transducers in typical pediatric investigations. Based on our own experiences and on review of the literature, 3DUS can be successfully used in infants and children for brain, spine, cardiac, urinary tract (particularly assessment of hydronephrosis, and virtual cystoscopy), and female genital (e.g., for assessment of uterine malformations) US, and for various other applications, particularly in small parts. Power Doppler data can be integrated, allowing 3DUS-angiography. Thus, 3DUS promises to become a useful adjunct for imaging children, particularly as it enhances ultrasound by offering additional, previously inaccessible planes, rendering options and surface assessments. 3DUS should be increasingly exploited, thus hopefully helping reduce the need for more invasive or burdening (e.g., ionizing radiation) investigations in children.

Pediatric uroradiology: state of the art

Recent years have witnessed major strides in imaging modalities, including US and contrast-enhanced voiding urosonography, fluoroscopy, CT and MRI, and these have significantly impacted paediatric uroradiology. The trend is towards reduced or no radiation exposure and combined morphological and functional imaging. This review presents the currently available and recommended modalities in modern paediatric uroradiology practice.

Catheter-free methods for vesicoureteric reflux detection: our experience and a critical appraisal of existing data

In recent years, the exact role of vesicoureteric reflux (VUR) in general has become controversial, though in some groups of children the knowledge of the existence or non-existence of VUR is still a very important issue. The number of techniques available for the assessment of VUR is increasing, and a new classification taking into account their real characteristics (direct/indirect, catheter-using/catheter-free, radiation-giving/radiation-free) has been proposed. The purpose of the following review is to evaluate the currently available evidence supporting the use of various catheter-free methods for VUR detection. We believe that as the clinical role of VUR has been questioned, it is even more important for the method of its detection to be user-friendly as regards catheterisation, radiation and availability. There is still no evidence supporting the assertion that any of the catheter-free methods of VUR detection might be the optimal one for any child. However, there are some groups of children who would benefit from using them. New studies using new, catheter-free methods of VUR detection or a combination of two or more of the methods described may prove useful in improving sensitivity and providing additional data on this important issue.