MR Voiding Cystography for Evaluation of Vesicoureteral Reflux
Department of Radiology, Lucile Packard Children's Hospital and Stanford University, 725 Welch Road, Stanford, CA 94305-5654, USA.American Journal of Roentgenology (Impact Factor: 2.73). 06/2009; 192(5):W206-11. DOI: 10.2214/AJR.08.1251
OBJECTIVE: The purpose of our study is to present a real-time interactive continuous fluoroscopy MRI technique for vesicoureteral reflux (VUR) diagnosis. CONCLUSION: MR voiding cystography with a real-time interactive MR fluoroscopic technique on an open MRI magnet is feasible for the evaluation of VUR in children.
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- "Another important limitation of VCUG is radiation exposure. It is estimated that as much as 25% of the radiation with potential to produce genetic alterations received by the pediatric population, is related to imaging of the urinary system, especially with VCUG. "
ABSTRACT: The purpose of the present study is to determine the accuracy of magnetic resonance voiding cystourethrography (MRVCUG) for diagnosis of vesicoureteral reflux (VUR) in children and adolescents with recurrent urinary tract infection (UTI). During the cross-sectional study from May 2009 to June 2011, 30 patients' (60 kidney-ureter units) MRVCUG findings by 1.5 T magnetic resonance imaging (MRI) were compared with voiding cystourethrography (VCUG) findings in patients with urinary tract infection. The sensitivity, specificity, positive and negative predictive values for MRVCUG were calculated. The sensitivity, specificity, positive and negative predictive values and accuracy for MRVCUG for detecting VUR were respectively 92.68% (95% CI: 80.57-97.48%), 68.42% (95% CI: 46.01-84.64%), 86.36% (95% CI: 71.95-94.33%), 81.25% (95% CI: 53.69-95.02%), and 85% (95% CI: 80.40-89.60%. The level of agreement between MRVCUG and VCUG findings for diagnosis VUR was very good (P < 0.001, according to Cohen's kappa value = 0.638). Studying correlation of low grade VUR (grade I and II) and high grade VUR (grade III-V) showed a very good agreement between MRVCUG and VCUG findings (P < 0.001, Cohen's kappa value = 0.754). MRVCUG could accurately reveal the presence and severity of VUR, especially in cases with high-grade (grade III-V) VUR in both children and adolescents.
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- "Other imaging techniques have been evaluated for VUR in infants (radionuclide cystography and contrast-enhanced voiding urosonography (ce-VUS) methods), although none give simultaneous imaging of the entire urinary system from kidney to urethra. Magnetic resonance imaging (MRI) presents an non-ionising radiation based alternative, although early attempts to demonstrate VUR with conventional MRI sequences typically required intravenous (IV) or oral sedation , IV fluids, IV diuretics or gadolinium, and were complicated by delays in switching between imaging sequences and locations   . "
ABSTRACT: Objectives: The current gold standard for diagnosing vesicoureteric reflux in unsedated infants is the X-ray-based Micturating CystoUrethroGram (MCUG). The aim of this study was to assess the diagnostic performance of interactive MRI for voiding cysto-urethrography (iMRVC). Methods: 25 infants underwent conventional MCUG followed by iMRVC. In iMRVC, patients were examined using a real-time MR technique, which allows interactive control of image contrast and imaging plane location, before, during and after micturition. Images were assessed for presence and grade of VUR. Parental feedback on both procedures was evaluated. Results: iMRVC gave a sensitivity of 100%, specificity of 90.5% (95% CI: 81.6-99.4%), PPV of 66.7% and NPV of 100% in this population. There was 88% concordance (44/50 renal units) according to the presence of VUR between the two methods, with iMRVC up-grading VUR in 6 units (12%). There was very good agreement regarding VUR grade: Kappa=0.66±0.11 (95% CI 0.43-0.88). 60% of parents preferred the MRI, but did not score the two tests differently. Conclusion: Interactive MRI allows dynamic imaging of the whole urinary tract without ionising radiation exposure. iMRVC gives comparable results to the MCUG, and is acceptable to parents.
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ABSTRACT: To evaluate the efficiency of magnetic resonance urography (MRU) in pediatric urology. We report retrospectively on 12 children who underwent MRU between January 1999 and November 2001. MRU was performed to accurately evaluate the entire urinary tract because of megaureter, ectopic ureter, vesicoureteral reflux, Y-inverted duplication and hydronephrosis because of pyeloureteral stenosis. T1- and T2-weighted images were obtained in the coronal, sagittal and axial planes. The mean age of the children (8 females, 4 males) investigated was 36 months (range 2-140 months). An accurate anatomical picture of the entire urinary tract could be obtained in all children. The obstructive nature of megaureter could be differentiated. The distal orifice of ectopic ureter could be identified in the vagina. Vesicoureteral reflux into the blind-ending ureteral bud of a duplicated system was accurately identified. Hydronephrosis was demonstrated to be the result of pyeloureteral stenosis. The location of stenoses was easily identified in the sagittal and coronal planes. MRU is an excellent imaging modality for accurately depicting the urinary tract. MRU is superior to conventional intravenous urography because it does not use ionizing radiation, the gadolinium contrast medium used is not nephrotoxic and the imaging quality is excellent, reproducible and not interfered with by gas superposition. Considering the high costs and diagnostic benefit of MRU compared to intravenous urography, MRU should be performed in patients with impaired renal function, in those with an allergy to contrast medium and if anatomic relationships are not clear prior to reconstructive surgery.
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