Urography In Children Research Articles

Functional MR urography in children - update 2023.

Functional MR urography (fMRU) has developed into an innovative, radiation-free option for assessing parameters of kidney function in pediatric radiology. The importance of fMRU in comparison to the standardized established nuclear medicine procedure (99mTc-Mercapto-acetyltriglycerine, MAG3 scintigraphy) is shown using SWOT analysis. To assess the current state of research, a selective literature search was carried out in PubMed. Taking into account the current scientific status, the examination technique, preparation, and evaluation of fMRU are presented. As a result of the comparison with MAG3, fMRU is suitable for certain indications and represents an optimal combination of morphological and functional representation of the kidneys and urinary tract, especially in the case of surgical consequences. fMRU has been successfully established as a diagnostic method for assessing the morphology and function of the kidneys in competition with MAG3 scintigraphy. · Functional MRU allows reliable statements on the morphology and function of the kidneys and urinary tract.. · The results of the functional assessment of fMRU are comparable to the results of MAG3 scintigraphy.. · The complex implementation and demanding evaluation limits the spread of fMRU as a complete alternative to MAG3 scintigraphy. fMRU is reserved for special indications.. · Functional MRU has prevailed over MAG3 scintigraphy for complex renal and urinary tract anomalies (CAKUT) that require surgical correction. An example is the clarification of dribbling in girls, which is usually based on an ectopic opening of a ureter in a double system.. · Kirsch H, Krüger P, John-Kroegel U et al. Functional MR urography in children - update 2023. Fortschr Röntgenstr 2023; 195: 1097 - 1105.

Functional Magnetic Resonance Urography in Children-Tips and Pitfalls.

MR urography can be an alternative to other imaging methods of the urinary tract in children. However, this examination may present technical problems influencing further results. Special attention must be paid to the parameters of dynamic sequences to obtain valuable data for further functional analysis. The analysis of methodology for renal function assessment using 3T magnetic resonance in children. A retrospective analysis of MR urography studies was performed in a group of 91 patients. Particular attention was paid to the acquisition parameters of the 3D-Thrive dynamic with contrast medium administration as a basic urography sequence. The authors have evaluated images qualitatively and compared contrast-to-noise ratio (CNR), curves smoothness, and quality of baseline (evaluation signal noise ratio) in every dynamic in each patient in every protocol used in our institution. Quality analysis of the image (ICC = 0.877, p < 0.001) was improved so that we have a statistically significant difference in image quality between protocols (χ2(3) = 20.134, p < 0.001). The results obtained for SNR in the medulla and cortex show that there was a statistically significant difference in SNR in the cortex (χ2(3) = 9.060, p = 0.029). Therefore, the obtained results show that with the newer protocol, we obtain lower values of standard deviation for TTP in the aorta (in ChopfMRU: first protocol SD = 14.560 vs. fourth protocol SD = 5.599; in IntelliSpace Portal: first protocol SD = 15.241 vs. fourth protocol SD = 5.506). Magnetic resonance urography is a promising technique with a few challenges that arise and need to be overcome. New technical opportunities should be introduced for everyday practice to improve MRU results.

Quantitative renal magnetic resonance imaging: magnetic resonance urography.

The goal of functional renal imaging is to identify and quantitate irreversible renal damage and nephron loss, as well as potentially reversible hemodynamic changes. MR urography has evolved into a comprehensive evaluation of the urinary tract that combines anatomical imaging with functional evaluation in a single test without ionizing radiation. Quantitative functional MR imaging is based on dynamic contrast-enhanced MR acquisitions that provide progressive, visible enhancement of the renal parenchyma and urinary tract. The signal changes related to perfusion, concentration and excretion of the contrast agent can be evaluated using both quantitative and qualitative measures. Functional evaluation with MR has continued to improve as a result of significant technical advances allowing for faster image acquisition as well as the development of new tracer kinetic models of renal function. The most common indications for MR urography in children are the evaluation of congenital anomalies of the kidney and urinary tract including hydronephrosis and renal malformations, and the identification of ectopic ureters in children with incontinence. In this paper, we review the underlying acquisition schemes and techniques used to generate quantitative functional parameters including the differential renal function (DRF), asymmetry index, mean transit time (MTT), signal intensity versus time curves as well as the calculation of individual kidney glomerular filtration rate (GFR). Visual inspection and semi-quantitative assessment using the renal transit time (RTT) and calyceal transit times (CTT) are fundamental to accurate diagnosis and are used as a basis for the interpretation of the quantitative data. The importance of visual assessment of the images cannot be overstated when analyzing the quantitative measures of renal function.

MR urography in children and adolescents: techniques and clinical applications.

Renal and urinary tract imaging is commonly performed in the pediatric population, particularly in the setting of suspected or known congenital anomalies. In most cases, adequate anatomic assessment can be achieved using ultrasound and fluoroscopic techniques, and evaluation of differential renal function and urinary tract drainage can be accomplished with renal scintigraphy. However, in a subset of children, anatomic or functional questions may remain after this routine evaluation. In this setting, magnetic resonance imaging (MRI) tailored to evaluate the kidneys and urinary tract, known as MR urography (MRU), can be used to depict the kidneys, ureters, and urinary bladder in detail and to determine differential renal function and assess urinary tract drainage. The objectives of this review article are to (1) describe pediatric-specific MRI techniques for assessment of the kidneys and urinary tract and (2) present common clinical applications for pediatric MRU where imaging can "add value" in terms of diagnosis and patient management.

Utility of MR urography in children suspected of having ectopic ureter

Conventional imaging modalities are limited in the assessment of complex lower urinary tract anomalies including ectopic insertion of ureters. MR urography can be useful in these situations. To share our experience with MR urography in assessing lower urinary tract anomalies and to determine its accuracy in depicting ectopic ureters. We conducted a retrospective review of all MR urography examinations done between November 2007 and March 2013 to note the presence or absence of duplex kidneys and insertion of ureters. We reviewed patient charts, surgical findings and results of other investigations including cystoscopy with retrograde ureterogram in order to establish presence or absence of ectopic ureter. This served as a reference standard against which we compared MR urography results. Of 22 MR urography examinations (3 boys, 19 girls; age range 3-16 years, mean 9.2 years) performed during the study period, 19 were performed to rule out ectopic ureters, two to assess complex anatomy and one to rule out crossing vessel in ureteropelvic junction obstruction. MR urography showed ectopic ureter in 9/19 children; one proved to be a false-positive. MR urography correctly showed normal insertion in 7/19 children. In the remaining 3/19 children distal ureter could not be seen, hence insertion was indeterminate on MR urography. One of these children had an ectopic ureter on cystoscopy and surgery. Statistical analysis showed MR urography's sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) to be 88.8-100%, 70-90%, 75-88.8% and 90-100% for the detection of ectopic ureter. MR urography is highly accurate in the assessment of ectopic ureters. In incontinent girls, MR urography should be the method of choice for depicting or ruling out ectopic ureter.

Diagnostic value of combined static-excretory MR Urography in children with hydronephrosis

The aim of this study was to determine the feasibility, accuracy and diagnostic potential of combined static-excretory MR Urography in children with sonographically detected hydronephrosis. We prospectively evaluated 28 children (11 girls and 17 boys), mean age 8.3years (range 2months–16years). Static-excretory MR Urography was performed in all cases. The results of MR Urography were compared with the results of other imaging modalities, cystoscopy and surgery. In 28 children, 61 renal units were evaluated by MR Urography (the renal unit is the kidney and its draining ureter). The final diagnoses included: normal renal units (n=23); uretropelvic junction obstruction (n=14); megaureter (n=8); midureteric stricture (n=1), complicated duplicated systems (n=5), post ESWL non-obstructive dilation (n=2), extrarenal pelvis (n=4), dysplastic kidney (n=4). Complex pathology and more than one disease entity in were found in 7 children. The MRI diagnosis correlated with the final diagnosis in 57 units, with diagnostic accuracy 93.4%. In conclusions static and excretory MRU give both morphological and functional information in a single examination without exposure to ionizing radiation and iodinated contrast agent. It is a valuable imaging technique for children with upper urinary tract dilatation; especially in cases of complex congenital pathologies and severely hydronephrotic kidney.

Lower-dose CT urography (CTU) with iterative reconstruction technique in children - initial experience and examination protocol.

SummaryBackgroundConventional X-ray urography is one of the basic imaging techniques in urinary tract diseases in children. CT urography (CTU) employing standard Filtered Back Projection (FBP) reconstruction algorithms is connected with higher radiation dose. Advanced iterative reconstruction techniques enable lowering the radiation dose to the level comparable with conventional X-ray urography with better visualization of the urinary tract. Study protocol and indications for this modified technique should be discussed.Material/MethodsIntroduction of iterative image reconstruction techniques allowed to significantly reduce the radiation dose delivered during examinations performed at our Department, including CT examinations of urinary tract in children. During the last two years, CT urography replaced conventional X-ray urography and became the basic imaging technique in our Department. We discuss the study protocol regarding pediatric CTU examinations. The main goal is to receive an optimal image quality at reduced radiation dose.ResultsCTU examinations performed using the standard filtered back projection (FBP) reconstruction technique are associated with radiation doses about 1.5 times higher than those in conventional X-ray urography. Implementation of iterative reconstruction algorithms in advanced CT scanners allow to reduce the radiation dose to a level comparable or even lower than that in X-ray urography. In addition, urinary tract can be evaluated more precisely in multiplanar reformatted (MPR) and volume rendered (VR) images.Conclusions1. Advanced iterative reconstruction techniques allow to reduce radiation dose in CT examinations and to extend indications for CT urography in children. 2. Urinary tract can be evaluated more precisely in multiplanar reformatted and volume rendered images. 3. CTU may replace conventional X-ray urography in children.

Magnetic resonance urography in children - when and why?

BackgroundThe aim of the study was to determine the potential of magnetic resonance urography (MRU) in evaluation of paediatric urinary tract pathologies.Patients and methods.Twenty-one paediatric urological patients were evaluated with T1, T2 prior and after and 3D gradient echo sequences after the contrast administration. Results were compared with findings obtained with ultrasound which was performed to all of patients, intravenous urography performed to 14 patients with the diagnosis of hydronephrosis and voiding cystouretrography performed to 6 patients where hydronephrosis was suspected to be caused by vesicoureteral reflux (VUR).ResultsMRU not only established the cause of hydronephrosis in all 14 cases (5 ureteropelvic junction (UPJ) stenosis, 1 functional stenosis, 3 residual hydronephrosis, 1 combination of UPJ and vesico-ureteric junction (VUJ) stenosis with hydromegaureter, 2 fetal ureters and 3 insufficient broad ureteral orifices), but gave additional information about existing pathological conditions in all of patients compared to other previously performed examination (1 caliceal lithiasis, 4 UPJ stenosis, 1 VUJ stenosis, 1 neurogenic bladder, 1 hypotonic ureter, 1 urinary infection, 1 duplication of pelvis and ureter, 1 urinary retention and 1 fetal ureter). Other MRU findings were: 3 polycystic kidney disease, 1 caliceal cyst, 2 simple renal cysts, 1 long hypotonic twisted ureters and 1 hypertrophied column of Bertini.ConclusionsBecause of the ability to acquire high contrast and spatial resolution images of the whole urinary tract in any orthogonal plane, MRU enables a precise detection and differentiation of pathological urological conditions. We believe that in the future, because of its advantages, MRU will replace traditional methods in the evaluation of urinary tract pathologies.

The Holy Grail of anatomic and functional MR urography in children

These three recent technical innovation papers [1–3] will (must) contribute to the discussion around how to properly perform MR urography (MRU) in children. While the contribution of MRU to the anatomical evaluation of uropathies is well accepted, its contribution to functional evaluation remains controversial as there is no complete consensus on how to perform functional MRU, what sequences to use or what and when to inject. Both teams have done a great job trying to explain, standardize and promote their methods, with both approaches having pros and cons. MR urography is a great imaging method; it has many indications and large potential in children. Yet, any risk should be made as small as possible. Therefore, not all gadolinium chelates should be administered, especially in infants. Furthermore, the use of sedation should be restricted whenever possible and performed optimally; bladder catheterisation should only be applied selectively. The contribution of the authors will help progress towards the Holy Grail of the “all-in-one method”. And yet still we are not at the end of the road. All data have to be validated properly and we have to collaborate with isotope specialists in order to strengthen our findings. All pitfalls have to be understood, for example, the relationship between signal and function has to be more clearly evaluated. In conclusion, this series of articles is a good representation of where we currently stand and provides a “how we do it” approach. However, this is not the final word, but on the contrary a starting point for further discussion on how the paediatric radiology community could or should use MRU, i.e. which aspects from which approach can be adapted and should be recommended. All these factors need to be integrated and improved. Further research and development are needed before MRU can be routinely implemented as a standard technique that is easily performed, well standardised and comparable. Only then can it be promoted for general use. This should also influence companies to integrate quantification software in the post-processing programs of their various workstations and viewing programs.

MR urography in children. Part 2: how to use ImageJ MR urography processing software

MR urography (MRU) is an emerging technique particularly useful in paediatric uroradiology. The most common indication is the investigation of hydronephrosis. Combined static and dynamic contrast-enhanced MRU (DCE-MRU) provides both morphological and functional information in a single examination. However, specific post-processing must be performed and to our knowledge, dedicated software is not available in conventional workstations. Investigators involved in MRU classically use homemade software that is not freely accessible. For these reasons, we have developed a software program that is freely downloadable on the National Institute of Health (NIH) website. We report and describe in this study the features of this software program.

MR urography in children. Part 1: how we do the F0 technique

MR urography (MRU) has been widely accepted as a substitute to intravenous urography for investigating children with a dilated urinary tract after preliminary assessment by US and voiding cystourethrography. Hydronephrosis is by far the main indication for MRU because upper tract dilatation is a frequent condition in infants and children. Recent advances in technology have allowed MR to go beyond morphology and to assess renal function parameters such as split renal function and drainage. In this article we report our routine practice of the F0 MRU technique. The main advantages of our protocol are no requirement for general anaesthesia, no bladder catheterization, use of low-dose gadolinium-based contrast agent (0.05-0.1 mmol/kg) and total acquisition time of 30 min or less.

MR urography in children: how we do it

In this article we introduce the topic of MR urography in children, focusing on the details required to obtain consistently high-quality scans. Much of the information presented is based on our experience during the last 7 years. We have performed almost 1,000 MR urograms in children, and the technique has evolved considerably during this time. We have learned through trial and error and have improved our protocols to the point that our approach is now standardized and reliably generates high-quality studies. From this standardized protocol, further refinements in technique can be readily implemented. It is important to remember that this clinical application is in its infancy and will improve significantly with further technical development. This paper provides an overview of the practical issues associated with obtaining high-quality scans as well as an introduction into the interpretation of MR urograms.

Magnetic Resonance Urography for Evaluating Outcomes After Pediatric Pyeloplasty

We report the role of magnetic resonance urography in children with ureteropelvic junction obstruction. Differential renal function, the single kidney glomerular filtration rate index, renal transit time, renal length and renal pelvis anteroposterior diameter were compared before and after pyeloplasty. Magnetic resonance urography was performed before and after pyeloplasty in 24 patients with a mean age of 1.9 years (range 3 months to 10 years). Renal length, renal transit time and renal pelvis anteroposterior diameter were determined by the radiologist. The volume of functioning renal tissue and descending aorta were segmented and the ratio of the volumes of functioning kidney tissue was used to calculate differential renal function. Rutland-Patlak plots were used to calculate single kidney glomerular filtration rate index, that is the Patlak score. Mean renal pelvis renal pelvis anteroposterior diameter was 3.3 cm preoperatively and 2.5 cm postoperatively (p = 0.0003). There was no difference in average renal length (p = 0.22). Of the 24 cases 22 (92%) showed stable or improved differential renal function. Improvement in renal transit time was seen in 20 of 23 cases (87%). Of 15 patients with complete Patlak scores 14 (93%) showed postoperative improvement. Mean preoperative and postoperative differential renal function, renal transit time and Patlak score were 36% and 41% (p = 0.003), 16.2 and 8.6 minutes (p = 0.0005), and 6.6 and 11.9 ml per minute (p = 0.01), respectively. Magnetic resonance urography provides superior anatomical and unprecedented functional information to fully define the preoperatively and postoperative status of corrected ureteropelvic junction obstruction. Magnetic resonance urography has the potential to become the imaging study of choice for evaluating pediatric hydronephrosis and obstructive uropathy.

MR urography in children

MR urography represents the next step in the evolution of uroradiology in children by combining superb anatomic imaging with quantitative functional evaluation in a single examination that does not use ionizing radiation. MR imaging has inherently greater soft-tissue contrast than other imaging techniques. When used in conjunction with dynamic scanning after administration of a contrast agent, it provides non-invasive analysis of the perfusion, concentration and excretion of each kidney. The purpose of this review is to outline our experience with more than 500 MR urograms in children. We outline our technique in detail, showing how we calculate differential renal function and how we assess concentration and excretion in the different regions of the kidney. We show that the dynamic contrast-enhanced data can be processed to yield quantitative measures of individual kidney GFR. In the clinical section we show how MR urography adds unique aspects to the anatomic evaluation of the urinary tract, and by combining the anatomic information with functional information, how we assess hydronephrosis and obstructive uropathy, congenital malformations, pyelonephritis and renal scarring.

Renal Transit Time With MR Urography in Children

Renal Transit Time With MR Urography in Children

MR urography in children

Thanks to the development of rapid sequences with better resolution, applications of uro MR have rapidly increased in children. Difficulties that remain are related to the variable ages of the patients. It is therefore mandatory to standardize as much as possible the techniques that are used in order to obtain reproducible results. In this review, the examination protocols will be explained. In a second part the current applications in children will be illustrated and discussed, especially in comparison with the other imaging techniques.

MAGNETIC RESONANCE UROGRAPHY IN CHILDREN: EVALUATION OF SUSPECTED URETERAL ECTOPIA IN DUPLEX SYSTEMS

We evaluate the diagnostic accuracy of magnetic resonance urography in children with suspected ectopic ureters and ureteroceles in duplex systems. A total of 14 children 4 weeks to 8 years old with a total of 18 duplex systems underwent magnetic resonance urography using a 1.5 tesla scanner. After injection of low dose furosemide, half-Fourier rapid acquisition with relaxation enhancement images were obtained for T2-weighted static fluid magnetic resonance urography. Respiratory gated 3-dimensional gradient echo images were acquired for T1-weighted excretory magnetic resonance urography 5 to 30 minutes after intravenously administered gadolinium. All magnetic resonance examinations were successfully performed without sedation. The diagnostic accuracy of T1-weighted excretory magnetic resonance urography depended on the renal function. Twelve duplex systems with a normal excretory function, including 6 bifid ureters and 6 upper moieties with inferomedial ectopic ureters, were analyzed correctly with the exception of a 6 mm. ureterocele in 1 case. In 6 duplex systems with poor or nonfunctioning upper moieties ectopic ureters were only demonstrated on T2-weighted magnetic resonance urograms. Respiratory gated excretory and static fluid magnetic resonance urography complement each other in the evaluation of duplex systems in children and provide high accuracy in the evaluation of suspected ectopic ureters and ureteroceles.

Tips for the Radiologist: When and how to perform intravenous urography in children

No abstract available.

MR urography in children: current status and future development.

The normal anatomy and many pathologies of the pediatric genitourinary system can be assessed with different imaging modalities. Most of them are based on the use of ionizing radiation and/or invasive techniques. The contribution of magnetic resonance imaging in this regard has opened new ways of approaching pathological conditions in this patient group. The addition of the newly developed rapid techniques has enhanced the superiority of MRI, and both morphological and functional evaluation of the genitourinary system can be achieved. There are different factors on which rely the optimization and the efficiency of magnetic resonance urography (MRU). Of importance is adequate patient immobilization and the use of optimal imaging sequences. The rapid technical development, including the advent of the post-processing respiratory navigator, allows acquisition of high-quality images independent of the patient's respiratory rate. In the future, it is expected that MRU, due to its non-use of ionizing radiation, will become the most important tool in the diagnostic work-up of genitourinary pathologies in infants and small children.

Excretory urography in children.

Excretory urography in children.