Magnetic resonance voiding cystourethrography for vesicoureteral reflux

Abstract

Purpose:To assess the feasibility of magnetic resonance voiding cystourethrography (MRVCUG) using MR fluoroscopy for evaluation of vesicoureteral reflux (VUR), and its use as a noninvasive alternative to standard VCUG. Materials and Methods:A total of 22 MR studies of 16 patients (five months to 41 years old) with primary VUR diagnosed by standard VCUG were evaluated. Six patients underwent MR studies and standard VCUG pre-and postoperatively. MR fluoroscopy was executed with a non-enhanced heavily T2-weighted single-shot fast spin-echo (FSE) sequence. The MR findings were correlated with those obtained by the gold standard, standard VCUG. Results:Of the 44 kidney-ureter units, 20 were refluxing on MRVCUG and 21 were refluxing on standard VCUG. There were one false-positive and two false-negative units. MRVCUG was 90% sensitive with a specificity of 96% for detecting VURs that were calculated based on kidney-ureter units. Two false-negative units were found in mild cases (grade I and II). For the units of grade III, IV, and V (highgrade reflux), MRVCUG detected all of the refluxing renal collecting systems. PRIMARY VESICOURETERAL REFLUX (VUR) is present in 25% to 40% of children with repeat cases of urinary tract infection (UTI) (1) and may cause renal scarring, particularly in patients with the severe form (2). Renal insufficiency and arterial hypertension is associated with renal damage caused by VUR and UTI in children. It is important to detect VUR before the onset of infection to prevent such complications (3). Voiding cystourethrography (VCUG) is the standard method for diagnosing VUR (4). However, its disadvantages include radiation exposure to the gonads, and urethral catheterization, which induces fear, distress, and pain in the patients and their parents (5). Radionuclide cystography is another sensitive method for detecting VUR. It can be performed with less radiation; however, the spatial resolution is unsatisfactory (6). Contrast-enhanced voiding urosonography has been shown to have high diagnostic accuracy comparable to that of VCUG (7), but both of these techniques are invasive. A variety of noninvasive methods using ultrasonography have been introduced for the diagnosis of VUR; however, these procedures are still not accurate enough or are less objective compared to conventional VCUG (8,9). The purpose of this study was to evaluate the feasibility of magnetic resonance VCUG (MRVCUG) as a noninvasive and non-radiating alternative to standard VCUG for diagnosing and managing patients with VUR. Conclusion MATERIALS AND METHODS SubjectsFrom September 2003 to January 2005, a total of 22 MRVCUG studies were performed on 16 patients (11 males and five females, 5 months to 41 years old, mean age ϭ 10.3 years) before and/or after anti-reflux surgery. Eleven patients were younger than seven years old, and six of these were between 5 and 12 months of age. Six patients underwent MRVCUG both pre-and postoperatively. Informed consent was obtained for all cases, and approval for this study was granted by the in...

Interactive magnetic resonance voiding cystourethrography (iMRVC) for vesicoureteric reflux (VUR) in unsedated infants: a feasibility study

“…Our sample size of 12 patients is small, but adequate to demonstrate feasibility, and comparable to previous MRIbased studies of VUR (6 to 20 subjects [12][13][14][15]). Some previous MRVC studies only examined children with known VUR, from which no sensitivity data can be obtained, unlike our study [13].…”

“…For MR imaging, this group is likely to be the hardest group to image in terms of signal-to-noise ratio and identifying small moving structures, but may yield fewer motion artefacts when compared with slightly older children. No previous study using MR to identify VUR has concentrated solely on the neonatal population (average ages 3 -10 years; [11][12][13][14]). Our study avoided the use of sedation [13,14], and demonstrates feasibility on a conventional closed bore MR system [15].…”

“…No previous study using MR to identify VUR has concentrated solely on the neonatal population (average ages 3 -10 years; [11][12][13][14]). Our study avoided the use of sedation [13,14], and demonstrates feasibility on a conventional closed bore MR system [15]. Some of the earlier studies did not demonstrate VUR directly, using either ureteral dilatation with increasing bladder filling [14], or a retrograde increase in time-intensity anterograde contrast curves, as surrogate markers of reflux [13].…”

“…Magnetic resonance imaging presents an obvious alternative to the use of X-rays in small children, and early attempts to demonstrate VUR with conventional MRI have been described in adults [11] as well as children [12][13][14][15]. However, these were relatively invasive as they required intravenous (IV) or oral sedation, IV fluids, IV diuretics or gadolinium, and complicated by delays in switching between imaging sequences and locations.…”

Non-invasive vesicoureteral reflux imaging

“…Takazakura et al [41] confirmed the diagnostic accuracy of MRVCUG compared to traditional VCUG. They compared 44 renal units, all of which were imaged both with MRVCUG and VCUG within a period of less than 1 month.…”