Hydronephrosis in pregnancy: simultaneous depiction of fetal and maternal hydronephrosis by magnetic resonance urography

Application of magnetic resonance urography in diagnosis of congenital urogenital anomalies in children

Magnetic resonance urography (MRU) has become a useful adjuvant in evaluating urogenital anomalies. In present study, we evaluated the ability of MRU in diagnosis of different congenital urogenital anomalies when the results of conventional imaging modalities were inconclusive. A total of 90 children were included in this series. The children were evaluated with T2-weighted and contrast-enhanced T1-weighted MRU sequences. The results were compared with findings obtained with ultrasonography, intravenous urography, renal nuclide scan, and voiding cystourethrography. MRU was requested in these children because conventional imaging modalities were equivocal or a co-existing urogenital anomaly was suspected. Only those cases that underwent surgery were included in this study and the surgical findings were set as the reference standard in statistical evaluation. The records of 61 boys with mean (range) age of 2.3 years (2 months-12 years) and 29 girls with mean (range) age of 3.3 years (3 months-12 years) were reviewed. The final diagnosis was ureteropelvic junction obstruction (n = 25), vesicoureteral junction obstruction (n = 16), ureterocele (n = 19), ectopic kidney (n = 11), posterior urethral valve (n = 17), and polycystic kidney (n = 2). The overall sensitivity of MRU, intravenous urography, renal nuclide scan, ultrasonography, and voiding cystourethrography in diagnosis of the aforementioned anomalies were 86, 63, 50, 44, and 41%, respectively. MRU was much more sensitive than other imaging modalities in diagnosis of end-ureteral dilation (100%) and ureterocele (89%). MRU provides a reliable noninvasive technique for imaging of the congenital anomalies in the urinary tract of children with T2-weighted MRU sequences providing unenhanced static-water images of the urinary tract as well as depicting adjacent soft-tissue lesions, and T1-weighted MRU technique imitating conventional intravenous urography. Both MRU sequences can be combined for a comprehensive examination of the urinary tract.

Magnetic resonance urography in pediatric urology

PURPOSE OF REVIEW

Magnetic resonance urography (MRU) has emerged as a powerful diagnostic tool in the evaluation of the pediatric genitourinary tract. The purpose of this review is to familiarize the reader with the basic techniques, strengths and limitations, as well as the current and potential future applications of MRU in pediatric urology.

RECENT FINDINGS

MRU can provide detailed anatomical information and assess renal function and drainage in a single study. MRU does not employ ionizing radiation and may be utilized in patients with iodine-based contrast allergy or impaired renal function. MRU has been most often applied to the evaluation of hydronephrosis and provides valuable insight into a wide range of obstructive uropathies. MRU was shown to be superior to renal scintigraphy for the diagnosis of pyelonephritis and renal scarring. The use of MRU for the assessment of urolithiasis and vesicoureteral reflux is limited and technical refinements are required. Potential future applications include fetal MRU, virtual endoscopy, and MRU-guided procedures. The development of new contrast agents and new image-processing software will further enhance the diagnostic potential of MRU in pediatric urology.

SUMMARY

MRU is currently thought of as a problem-solving tool to define anatomy and function when conventional methods fall short. This technique is likely to emerge as the imaging modality of choice for children with complex genitourinary pathology.

Comparison of magnetic resonance urography with ultrasound studies in detection of fetal urogenital anomalies

PURPOSE

Prenatal ultrasonography detects the vast majority of urogenital anomalies, but in some cases the diagnosis remains in doubt. We assessed the potential of magnetic resonance urography (MRU) in the evaluation of different urogenital anomalies in fetuses when ultrasound study was equivocal.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 46 fetuses in whom the presence of urogenital anomalies was suspected at ultrasound studies, but remained inconclusive. Fetal MRU was performed within the same week as ultrasound studies. All patients underwent MRU, comprising overview, fast, thick-slab, heavily T2-weighted sequences, followed by focused, high-resolution T2-weighted sequences obtained in sagittal, axial and coronal planes. T1-weighted sequences were obtained in selected cases for assessment of the gastrointestinal tract. All MRU results were compared with ultrasound findings. Sensitivity of each imaging modality was estimated based on definite diagnoses made after birth or abortion.

RESULTS

The mean (range) gestational age was 27 (18-36)weeks. The final diagnosis was ureteropelvic junction obstruction in 12, ureteral dilation (due to vesicoureteral junction obstruction) in five, ureterocele in five, posterior urethral valve in 16, multicystic dysplastic kidney in six, mesenteric cyst in one and abdominoscrotal hydrocele in one. Overall diagnostic sensitivity of fetal MRU was 96% compared to sonography with 58% sensitivity (p<0.05). Fetal MRU studies provided additional information to sonography in 17 (37%) cases, and were especially more sensitive in evaluation of ureteral anatomy.

CONCLUSIONS

Fetal MRU can accurately diagnose a wide variety of urinary tract disorders and must be regarded as a valuable complementary tool to ultrasound in the assessment of the urinary system, particularly in cases of inconclusive ultrasound findings. The present study had a selection bias, as only fetuses with possible anomalies proposed by sonography were referred for MRU; however, this is the population that probably benefits most from MRU studies.

Managing severe loin pain in pregnancy

OBJECTIVE

To investigate whether the intravenous urogram used in an appropriate setting is a valuable investigation for managing severe loin pain in pregnancy.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

POPULATION

Fifteen pregnant women referred with severe loin pain.

METHODS

A prospective study collecting data over a 24-month period was performed. Women with severe loin pain believed to be of renal origin that had failed to respond to conservative treatment were referred by their obstetricians. The intravenous urogram was performed that consisted of a two-film series (plain film and a 20-minute postmicturition film).

MAIN OUTCOME MEASURES

Management of severe loin pain in pregnancy based on the findings of the intravenous urogram.

RESULTS

Over the two-year period, 15 women had an intravenous urogram performed at a median gestation of 32 weeks (24-36 weeks). All women had undergone a prior urinary tract ultrasound examination within 24 hours of referral, which showed dilatation on the symptomatic side in 15/15 cases. The intravenous urogram confirmed dilatation on the ipsilateral side in 14/15 cases and revealed the level of dilatation in all of these cases. Delayed excretion of contrast was seen in all 14/15 cases. Three patients had obstructing ureteric calculi revealed by the intravenous urogram and one patient had a non-dilated and non-obstructed system.

CONCLUSIONS

An intravenous urogram is a safe investigation in the appropriate setting. It allows for an accurate diagnosis to be made and for appropriate treatment to be instigated with joint decisions from urologic, obstetric and radiologic teams. This multidisciplinary approach care can be specifically tailored to the individual patient, which we feel is safer for both mother and baby.

Magnetic resonance urography in patients with neurogenic bladder dysfunction and spinal dysraphism

OBJECTIVE

To investigate the reliability of magnetic resonance urography (MRU) using heavily T2-weighted very fast spin-echo sequences in imaging the upper urinary tract in patients with spinal dysraphism and neuropathic bladder dysfunction.

PATIENTS AND METHODS

Patients with neuropathic bladder dysfunction secondary to spinal dysraphism may have gross spinal deformity, which makes assessing the urinary tract extremely difficult by ultrasonography or intravenous urography. The study included 50 patients (median age 33 years, range 19-52) with a median (range) Cobb's angle of 60 (0-240) degrees. No contrast medium was given but all patients received 20 mg of intramuscular frusemide 20-30 min before MRU.

RESULTS

Thirty-five patients had previous ultrasonography, during which only 42 kidneys and no ureters were visible. Of the 94 renal tracts, MRU visualized all kidneys and 86 (89%) ureters. There was good agreement amongst observers on assessing the kidneys and pelvicalyceal systems (kappa > or = 0.61) but only moderate agreement on evaluating the ureters (kappa < or = 0.61). There was disagreement on normality vs renal parenchymal scarring in 14 (15%) kidneys, about no dilatation vs dilatation of the pelvicalyceal system in 14 (15%) systems and about no dilatation vs dilatation of the ureter in 20 (22%) ureters. The overall quality of the MRU images was rated highly, with a mean (range) score of 4.6 (3-5).

CONCLUSION

MRU provides a reliable noninvasive technique for imaging the upper tract in patients who were previously difficult to investigate.