High resolution MR for evaluation of lower urogenital tract malformations in infants and children: feasibility and preliminary experiences

Case series: Comparison of contrast-enhanced genitosonography (ceGS) to fluoroscopy and cone-beam computed tomography in patients with urogenital sinus and the cloacal malformation

In this case series, contrast enhanced genitosonography is compared to genitography performed using fluoroscopy and cone-beam computed tomography in patients with urogenital sinus and the cloacal malformation. The method of contrast enhanced genitosonography is described, including contrast preparation, contrast administration, ultrasound imaging approaches, as well as the benefits and potential pitfalls of this technique compared to fluoroscopy and computed tomography.

Use of MR Urography in Pediatric Patients

PURPOSE OF REVIEW

In this article, we describe the basics of how magnetic resonance urography (MRU) is performed in the pediatric population as well as the common indications and relative performance compared to standard imaging modalities.

RECENT FINDINGS

Although MRU is still largely performed in major academic or specialty imaging centers, more and more applications in the pediatric setting have been described in the literature. MRU is a comprehensive imaging modality for evaluating multiple pediatric urologic conditions combining excellent anatomic detail with functional information previously only available via renal scintigraphy. While generally still reserved for problem solving, MRU should be considered for some conditions as an early imaging technique.

European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology

At the occasion of the European Society of Paediatric Radiology (ESPR) annual meeting 2015 in Graz, Austria, the newly termed ESPR abdominal (gastrointestinal and genitourinary) imaging task force set out to complete the suggestions for paediatric urogenital imaging and procedural recommendations. Some of the last missing topics were addressed and proposals on imaging of children with anorectal and cloacal malformations and suspected ovarian torsion were issued after intense discussions and a consensus finding process that considered all evidence. Additionally, the terminology was adapted to fit new developments introducing the term pelvicalyceal dilatation/distension (PCD) instead of the sometimes misunderstood hydronephrosis. The present state of paediatric urogenital radiology was discussed in a dedicated minisymposium, including an attempt to adapt terminology to create a standardised glossary.

Magnetic resonance urography in the pediatric population: a clinical perspective

Diagnostic imaging in pediatric urology has traditionally relied upon multiple modalities based on availability, use of ionizing radiation, and invasiveness to evaluate urological anomalies. These modalities include ultrasonography, voiding cystourethrography, fluoroscopy and radionuclide scintigraphy. Magnetic resonance urography (MRU) has become increasingly useful in depicting more detailed abdominal and pelvic anatomy, specifically in duplex collecting systems, ectopic ureter, ureteropelvic junction (UPJ) obstruction, megaureter and congenital pelvic anomalies. Here we discuss the clinical role of MRU in the pediatric population and its future direction.

Optimizing functional MR urography: prime time for a 30-minutes-or-less fMRU

BACKGROUND

Current protocols for functional MR urography (fMRU) require long scan times, limiting its widespread use.

OBJECTIVE

Our goal was to use pre-defined criteria to reduce the number of sequences and thus the examination time without compromising the morphological and functional results.

MATERIALS AND METHODS

The standard fMRU protocol in our department consists of eight sequences, including a 17-min dynamic post-contrast scan. Ninety-nine children and young adults (43 male, 56 female, mean age 7 years) were evaluated with this protocol. Each sequence was retrospectively analyzed for its utility and factors that affect its duration.

RESULTS

Mean scan time to perform the eight sequences, without including the variable time between sequences, was 40.5 min. Five sequences were categorized as essential: (1) sagittal T2 for planning the oblique coronal plane, (2) axial T2 with fat saturation for the assessment of corticomedullary differentiation and parenchymal thickness, (3) coronal 3-D T2 with fat saturation for multiplanar and 3-D reconstructions, (4) pre-contrast coronal T1 with fat saturation to ensure an appropriate scan prior to injecting the contrast material and (5) the coronal post-contrast dynamic series. Functional information was obtained after 8 min of dynamic imaging in the majority of children. The coronal fat-saturated T2, coronal T1, and post-contrast sagittal fat-saturated T1 sequences did not provide additional information. Because of the effects of pelvicalyceal dilation and ureteropelvic angle on the renal transit time, prone position is recommended, at least in children with high-grade pelvicalyceal dilation.

CONCLUSION

Comprehensive fMRU requires approximately 19 min for sequence acquisition. Allowing for time between sequences and motion correction, the total study time can be reduced to about 30 min. Four pre-contrast sequences and a shortened post-contrast dynamic scan, optimally with the child in prone position, are sufficient.

Utility of MR urography in children suspected of having ectopic ureter

BACKGROUND

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.

OBJECTIVE

To share our experience with MR urography in assessing lower urinary tract anomalies and to determine its accuracy in depicting ectopic ureters.

MATERIALS AND METHODS

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.

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.

CONCLUSION

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.

ESPR uroradiology task force and ESUR Paediatric Work Group--Imaging recommendations in paediatric uroradiology, part VI: childhood renal biopsy and imaging of neonatal and infant genital tract. Minutes from the task force session at the annual ESPR Meeting 2012 in Athens on childhood renal biopsy and imaging neonatal genitalia

The European Society of Paediatric Radiology Uroradiology Task Force and the ESUR Paediatric Work Group jointly publish guidelines for paediatric urogenital imaging. Two yet unaddressed topics involving patient safety and imaging load are addressed in this paper: renal biopsy in childhood and imaging of the neonatal genital tract, particularly in girls. Based on our thorough review of literature and variable practice in multiple centers, procedural recommendations are proposed on how to perform renal biopsy in children and how to approach the genital tract in (female) neonates. These are statements by consensus due to lack of sufficient evidence-based data. The procedural recommendation on renal biopsy in childhood aims at improving patient safety and reducing the number of unsuccessful passes and/or biopsy-related complications. The recommendation for an imaging algorithm in the assessment of the neonatal genital tract focuses on the potential of ultrasonography to reduce the need for more invasive or radiating imaging, however, with additional fluoroscopy or MRI to be used in selected cases. Adherence to these recommendations will allow comparable data and evidence to be generated for future adaptation of imaging strategies in paediatric uroradiology.

Value of diagnosis imaging in the evaluation of the severity of histological lesions in duplex systems

OBJECTIVE

In order to determine the effectiveness of imagery in the assessment of the severity of histological lesions in duplex systems in children we compared histology results from heminephrectomies with diagnosis imaging findings [renal ultrasound (US), scintigraphy, unenhanced and contrast-enhanced magnetic resonance imagery (MRI)].

MATERIALS AND METHODS

Between 2007 and 2013, 34 children with duplex system underwent surgery. The results from US (n = 34), dimer captosuccinic acid scintigraphy (n = 23) and MRI (n = 16) were compared with histological data. Five histological lesions were found (chronic interstitial inflammation, interstitial fibrosis, tubular atrophy, glomerulosclerosis and dysplasia) and categorized as severe (>25%) or moderate (≤ 25%).

RESULTS

Severe histological lesions were found in 76.5% and moderate lesions in 23.5%. Radiological features were compared with histological results. In US, severe parenchymal thinning was associated with chronic interstitial inflammatory. The absence of parenchymal enhancement and/or severe cortical thinning in MR urography (MRU) was significantly associated with interstitial fibrosis. All poorly functioning poles were associated with severe histological lesions (p = 0.091), but not to a specific category of lesions.

CONCLUSIONS

MRI sensibility was excellent (90%) in the diagnosis of poorly functioning pole. Severe thinning on US and minimal pole function on MRU can be used to predict the severity of histological lesions.

Magnetic resonance urography and laparoscopy in paediatric urology: a case series

Paediatric urology often presents challenging scenarios. Magnetic resonance urography (MRU) and laparoscopy are increasingly used. We retrospectively studied children affected by a disease of the upper urinary tract who after MRU were elected for laparoscopic treatment. This pictorial essay draws on our experience; it illustrates some specific MRU findings and highlights the usefulness of MRU for the diagnosis of upper urinary tract pathology in children. It also offers some examples of the potential additional diagnostic information provided by laparoscopy as well as its therapeutic role.

[Urinary dribbling in girls: which investigations in 2012?]

Continuous urinary leakage, despite normal deliberate voiding, must suggest the diagnosis of ectopic ureter, more specifically in girls. Ectopic ureter is usually associated with duplex kidney and complete ureteral duplication. The strategy of investigations has changed over the past few years, due to MRI development in the analysis of urinary tract malformations. We report the case of a 4-year-old girl who presented with these symptoms and had a suspicion of left duplex kidney on the prenatal ultrasonography (US). Two US examinations during the first months of life were compatible with a left duplex kidney without any complication. Another US at the age of 4 years was reported as normal. We completed the investigation with MR urography, which revealed a left duplex kidney with a poorly functioning dysplastic upper pole, and the orifice of the ureter of this upper pole inserting in the vagina. The surgical treatment, realized by celioscopy, was partial nephrectomy of the upper pole, removing most of the ectopic ureter. US is the first exam to investigate urinary tract malformations. However, duplex kidney with small dysplastic pole and ectopic insertion of a nondilated ureter may be difficult to see, and a normal US should never end the investigations. Intravenous urography and renal scintigraphy used to be the reference complementary exams, but are now replaced by MR urography. Without using ionizing radiation, MR urography can visualize duplex kidney and ectopic ureteral insertion with high resolution, and evaluates renal function of each kidney and each pole. These morphological and functional data are essential to determine the surgical treatment.

MR imaging of the abdomen and pelvis in infants, children, and adolescents

Recent developments in magnetic resonance (MR) imaging have profoundly changed the investigation of abdominal and pelvic disease in pediatrics. Motion reduction techniques, such periodically rotated overlapping parallel lines with enhanced reconstruction, or PROPELLER, have resulted in reliable imaging with quiet breathing. Faster imaging sequences minimize artifact and allow for more efficient studies. Diffusion-weighted imaging has become increasingly important in the evaluation of neoplastic disease, depicting disease with increased cellularity and helping to differentiate benign from malignant masses. MR enterography helps visualize intra- and extraluminal bowel pathologic conditions. MR cholangiopancreatography can depict congenital and acquired causes of pancreatic and biliary abnormalities. MR urography is an effective technique for a one-stop-shop evaluation of structural urinary tract abnormality and renal function. Three-dimensional acquisitions allow volumetric display of structures from multiple angles. Specialized techniques allow quantification of iron and fat in the viscera in children with hemolytic anemia and obesity, respectively. This article covers current techniques and strategies to perform and optimize MR imaging of the abdomen and pelvis in infants, children, and adolescents and describes important practical applications.

Obstructive diseases of the urinary tract in children: lessons from the last 15 years

Imaging urinary tract obstruction is a common query in paediatric uroradiology. With the advent of a more conservative treatment approach, the task of imaging today is to distinguish as early as possible those kidneys that do not require surgery, from those that will deteriorate and lose function and/or growth potential and thus benefit from surgery. At present, in spite of significant advancements in imaging and the introduction of diuretic paediatric MR-urography, there is still no reliable a-priori pro-futuro assessment. Thus, repeated follow-up imaging is often necessary for monitoring. Imaging usually starts with US; the major additional complementary and more function-oriented tools are diuretic renal scintigraphy and MR-urography. The frequency and timing as well as the detailed protocol vary within institutions, partly because of differences in the criteria that are used for indicating surgery. Intra-venous urography (IVU) for obstruction has practically vanished apart from for a few exceptions, and the "Whitaker" test is today seldom performed, being reserved for complicated cases.