Comparison of direct radionuclide cystography and voiding direct cystography in the detection of vesicoureteral reflux

PURPOSE: The aim of this study is to compare the results of direct radionuclide cystography (DRNC) and voiding cystourethrography (VCUG) in a group of children with a high suspicion of vesicoureteral reflux (VUR). METHODS: For this purpose, 25 children were studied with both VCUG and DRNC. Among 50 ureter units able to be compared 39 ureter units did not show any VUR on either study. Eleven ureter units (10 children) had VUR either on one study or on both (VCUG and DRNC). In the children who had VUR on either study, a dimercaptosuccinic acid scintigraphy (DMSA) was performed to determine their cortical function. RESULTS: We identified the following four patterns: 1) Five ureter units (five children) read positive on DRNC who were negative on VCUG and four of these children had positive findings on DMSA; 2) Four ureter units (four children) read positive on VCUG who were negative on DRNC, and two of them had positive findings on DMSA; 3) Two ureters (one child) read positive in both studies and also had abnormal DMSA findings; 4) Thirty-nine ureter units read as negative on both studies. CONCLUSION: Although the results of these two methods did not show a significant difference, DRNC offers a high sensitivity in the younger age group whereas VCUG seems to be more sensitive in the older age group. DRNC also offers continuous recording during the study, ease of assessment and lower radiation dose to the gonads, which makes it a preferable method for the initial diagnosis and follow-up of VUR.     

Magnetic resonance voiding cystography in the diagnosis of vesicoureteral reflux: comparative study with voiding cystourethrography

PURPOSE: To evaluate the feasibility of magnetic resonance voiding cystography (MRVC) compared with voiding cystourethrography (VCUG) for detecting and grading vesicoureteral reflux (VUR). MATERIALS AND METHODS: MRVC was performed upon 20 children referred for investigation of reflux. Either coronal T1-weighted spin-echo (SE) or gradient-echo (GE) (fast multiplanar spoiled gradient-echo (FMPSPGR) or turbo fast low-angle-shot (FLASH)) images were obtained before and after transurethral administration of gadolinium solution, and immediately after voiding. The findings of MRVC were compared with those of VCUG and technetium-99m ((99m)Tc) dimercaptosuccinic acid (DMSA) single-photon emission computed tomography (SPECT) performed within 6 months of MRVC. RESULTS: VUR was detected in 23 ureterorenal units (16 VURs by both methods, 5 VURs by VCUG, and 2 VURs by MRVC). With VCUG as the standard of reference, the sensitivity of MRVC was 76.2%; the specificity, 90.0%; the positive predictive value, 88.9%; and the negative predictive value, 78.3%. There was concordance between two methods regarding the grade of reflux in all 16 ureterorenal units with VUR detected by both methods. Of 40 kidneys, MRVC detected findings of renal damage or reflux nephropathy in 13 kidneys, and (99m)Tc DMSA renal SPECT detected findings of reflux nephropathy in 17 kidneys. CONCLUSION: Although MRVC is shown to have less sensitivity for VUR than VCUG, MRVC may represent a method of choice offering a safer nonradiation test that can additionally evaluate the kidneys for changes related to reflux nephropathy.     

Magnetic resonance voiding cystourethrography for vesicoureteral reflux

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 (high-grade reflux), MRVCUG detected all of the refluxing renal collecting systems. CONCLUSION: MRVCUG can demonstrate high-grade reflux without ionizing radiation or catheterization.     

核素直接法膀胱显像对膀胱输尿管返流的分级

为了使核素直接法膀胱显像（ＤＲＣ）用于膀胱输尿管返流（ＶＵＲ）分级，使ＤＲＣ更有效地指导ＶＵＲ的治疗，以ＶＵＲ国际分级标准为依据，结合核素显像的特点提出ＤＲＣ的返流分级标准。对２８例ＶＵＲ患儿，同期分别做ＤＲＣ和Ｘ线排尿性膀胱尿道造影（ＭＣＵ）检查，按ＤＲＣ分级标准将返流分级与ＭＣＵ分级进行对比。结果：ＤＲＣ分级与ＭＣＵ分级完全相同有３５侧（８３３３％），比ＭＣＵ低１级４侧（９５２％），比ＭＣＵ低２～３级３侧（７１４％）。因此，ＤＲＣ的返流分级标准能客观准确地反映返流的程度，其结果基本与ＭＣＵ相似，有助于指导临床治疗ＶＵＲ。     

How good is technetium-99m mercaptoacetyltriglycine indirect cystography?

The aim of the present study was to estimate the sensitivity of indirect radionuclide cystography (IRC) performed with technetium-99m mercaptoacetyl-triglycine (MAG3), in comparison with the micturition cystourethrography (MCUG) and direct radionuclide cystography (DRC), for the diagnosis of vesicoureteric reflux. Two groups of patients were selected: group I comprised 40 children who underwent IRC during the acute phase of urinary tract infection and an MCUG 6 weeks later; group II comprised 42 (other) children with known reflux, who underwent IRC and DRC during follow-up. Taking as the reference the total number of refluxing kidneys detected by means of any cystographic technique, ^99mTc-MAG3 ICR missed two-thirds of the refluxing kidneys. Most of the small refluxes were missed, but so too were 50% of the major refluxes. Taking as the reference ^99mTc dimercaptosuccinic acid (DMSA) scintigraphy, MCUG detected 91 % of the patients with DMSA abnormalities on at least one kidney, DRC detected 95%, and IRC detected 46% and 43% respectively, in groups I and II. The use of ^99mTc-MAG3 IRC as the sole technique for the detection of vesicoureteric reflux gives rise to an unacceptable number of false-negative results. Correspondence to: C. De Sadeleer     

Simultaneous voiding cystourethrography and voiding urosonography

Purpose: 
To compare the diagnostic accuracy of contrast-enhanced voiding urosonography (VUS) and voiding cystourethrography (VCUG) during simultaneous performance of both examinations. Material and Methods: 
A total of 24 children, 16 girls and 8 boys, with a mean age of 3.5 years referred for reflux examination were recruited for the study. After transurethral bladder catheterization, radiographic contrast medium, followed directly by the US contrast medium, were administered. Fluoroscopic VCUG and VUS were carried out concurrently in the same patient. When 1 kidney was scanned by ultrasound, fluoroscopy was performed on the contralateral side. Results: 
In 19 of the 47 kidney-ureter-units (KUU) vesicoureteral reflux (VUR) was detected. In 16 units the reflux was detected by both VCUG and VUS. In 3 KUUs the reflux was detected only at VCUG. All 3 cases were grade 1. Taking the VCUG as the reference standard, VUS had 84% sensitivity, 100% specificity, 100% and 90% positive and negative predictive values, respectively. Conclusion: 
A dependable comparison could be achieved by performing VCUG and VUS at the same time and under the same conditions. It reconfirmed that VUS is reliable in the exclusion or verification of reflux.     

Effectiveness of direct and indirect radionuclide cystography in detecting vesicoureteral reflux.

A modification of the direct radionuclide cystography technique to include filling, voiding, and postvoiding phases of the examination permitted a simulated comparison between direct and indirect radionuclide cystography. One hundred thirty-seven examples of reflux were documented with this technique. Of these, 96 instances of reflux (70%) were recorded during two or more phases and thus would have been detected by either technique. Twenty-nine examples (21%) were only detected during filling and thus would have been missed by the indirect radionuclide technique and by some roentgenographic techniques. Only 12 examples (9%) were detected during the voiding phases only. The modified direct method of radionuclide cystography, which continuously monitors the urinary tracts during filling, voiding, and postvoiding, is offered as the best current technique for assessing vesicoureteral reflux.     

Intravenous contrast-enhanced dynamic MR urography: diagnosis of vesicoureteral reflux during bladder filling with time-signal intensity curves

Purpose

To evaluate the time‐signal intensity (SI) curves generated from intravenous (IV) gadodiamide‐enhanced dynamic magnetic resonance (MR) urographic scans for identifying vesicoureteral reflux (VUR) during bladder filling.

Materials and Methods

MR urographic studies of children were retrospectively reviewed, and 52 ureterorenal units of 26 patients (15 females and 11 males, mean age = 5.5 years) who had also undergone voiding cystourethrographic (VCUG) examination were included in this study. The patients were examined on a 1.5T scanner. For functional MR urography and to generate time‐SI curves, we used a post IV contrast‐enhanced two‐dimensional (2D) fast field echo (FFE) sequence (TR = 17 msec, TE = 3.2 msec, flip angle (FA) = 90°) in the coronal plane. MR urographic time‐SI curves that demonstrated a prompt and concave fall of the initial third phase followed by intermittent or constantly increasing SI peaks above the baseline from which the second phase starts were considered to have VUR. We compared the differences in time‐SI curves between the control group and patients with VUR during bladder filling.

Results

Twelve ureterorenal units of eight patients (four bilateral and four unilateral) had VUR during bladder filling on VCUG. The time‐SI curves of these patients showed intermittent (N = 8 ureterorenal units), and constantly increasing (N = 4 ureterorenal units) SI peaks consistent with VUR. One patient also had bilateral abnormal time‐SI curves suggesting VUR despite the normal VCUG study. In the control group, 25 units had normal triphase time‐SI curves, six renal units had urinary dilatation with good washout after diuretic injection, and four renal units had upper urinary dilatation without contrast washout, while five renal units did not show any function. None of the patients in the control group revealed distortion in the time‐SI curve. The differences in time‐SI curves patterns between the control group and patients with VUR during bladder filling were statistically significant (P < 0.001).

Conclusion

After a prompt and concave decrease of the initial third phase of the time‐SI curve, intermittent spikes or a constant rise in SI above the baseline suggest the existence of VUR. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.

     

Radiation dose to the bladder wall and the gonads from direct radionuclide cystography in children

A dynamic spherical bladder model, previously developed in our laboratory, was implemented to evaluate the absorbed dose to the bladder wall from ^99mTc-pertechnetate and direct radionuclide cystography (DRC). This model takes into account the flow rate of normal saline into the bladder and the bladder volume as a function of the filling time. The DRC examinations of 36 children were analysed and calculations were carried out in order to estimate (a) the absorbed dose to the bladder during and following the DRC examination and (b) the gonadal dose. It is shown that the estimated dose to the bladder wall is much greater than that estimated by static models. It is also shown that the absorbed dose to the bladder due to the activity in the residual urine following the examination is even greater than the dose received during the DRC procedure. Our results indicate that in order to reduce the radiation burden, besides the so far proposed precautions, concerning the shortening of the DRC procedure, the patient should also be well hydrated and encouraged to void frequently after the examination.     

Indirect radionuclide renocystography for determination of vesico-ureteral reflux in children

Indirect radionuclide renocystography (IRRCG) is a method for the detection of vesico-ureteral reflux by analysis of the activity-time curves over the kidneys and bladder during voiding of urine about 30 min after intravenous administration of a radioactive indicator. This paper presents a new method for detection of reflux by a statistical test, the magnitude of the reflux is evaluated by the reflux volume per 1.73 m² body surface area. Residual urine volume and urine voiding efficiency are also calculated. In a retrospective study of 154 children examined for renal and urological diseases consisting mainly of urinary tract infections, vesico-ureteral reflux was found by IRRCG in 16% of the kidneys (23% of the children). Reflux volumes were below 10 ml/1.73 m² in 90% of the children with reflux. The mode value of the reflux volume was 2 ml/1.73 m². For a subgroup of 97 children, the results were compared with micturating cysto-urethrography (MCU). This showed that a negative IRRCG in conjunction with the renal mean transit time of the radioactive indicator determined by gamma camera renography could be used as a screening test for vesico-ureteral reflux when MCU was considered a true reference method. Hence, about 75% of the invasive and high radiation dose MCU can be replaced by the non-invasive and low radiation dose IRRCG. The discrepancies between the two methods and the reasons for them are discussed.     

Echo-enhanced color Doppler cystosonography of vesicoureteral reflux in children. Improvement by stimulated acoustic emission

Purpose:
To prospectively evaluate the potential of echo-enhanced color Doppler sonography (ee-CDS) using the acoustic stimulated emission technique in the diagnosis of vesicoureteral reflux (VUR) in children. Material and Methods:
30 children (age: 0-9 years) with suspicion of VUR were submitted for echo-enhanced cystosonography (ee-CS) and conventional voiding cysto-urethrography (VCU). Conventional US and then color Doppler sonography (CDS) were performed after instillation of Levovist into the catheterized urinary bladder that had been prefilled with saline. Finally, output gain was increased in order to 'burst' the bubbles (= stimulated acoustic emission, burst-CS). Thereafter VCU was performed in the same session. The results of conventional ee-CS and burst-CS were compared to VCU findings. Results:
Twenty-four refluxing systems were found in a total of 66 collecting systems by both techniques. Ee-CS and burst-CS detected VUR in four systems not seen by VCU (grades 1-4), but missed low-degree VUR in 2 cases. In low-degree VUR, burst-CS was particularly helpful in 9 patients with equivocal results on conventional ee-CS. In 6 of them, VUR was proven by burst-CS, the other 3 showed VURs neither on VCU nor on burst-CS. Conclusion:
Levovist ee-CS is feasible in the pediatric bladder. It enables reliable visualization of VUR in the renal collecting system. Burst-CS improves visualization of contrast reflux, particularly in non-dilative or minimally dilative VUR, which is sometimes difficult to depict with conventional ee-CS.     

Malposition of catheters during voiding cystourethrography

The aim of this study was to report catheter malposition during voiding cystourethrography. Eight hundred forty-three voiding cystourethrography (265 males and 578 females, aged 1 week to 12 years, mean age 2 years) were performed during a period of 4 years. The conventional standard procedure was applied. In 3 cases with passed history of urinary tract infection the catheter entered directly into the ureter. In all these cases the uretero-vesical reflux was present on the same side where the catheter entered. It appears that insertion of a catheter into the ureter is possible only in the presence of an anomaly or pathology at the vesicoureteric junction. Received: 25 January 2000 Revised: 31 May 2000 Accepted: 5 June 2000     

Sonographic detection of vesicoureteral reflux with air: a new method

A new method of detecting vesicoureteric reflux (VUR) is presented, utilizing ultrasound as the imaging modality. During the filling phase of a gas cystogram and during micturition, gas bubbles can be seen in the renal pelvis in cases of reflux. In 107 pediatric patients, sonographic reflux studies were performed and compared with radiographic voiding cystourethrograms. The accuracy of the sonographic reflux study was 93.4%, the sensitivity of grade III– IV was 100%, and the specificity was 95.6%. Hence sonographic reflux studies with air have been incorporated into our routine. Since that time, the number of voiding cystourethrograms has decreased by over 80%. Correspondence to: G. Alzen     

Enhanced detection of vesicoureteral reflux in infants and children with use of cyclic voiding cystourethrography.

Cyclic voiding cystourethrography (VCUG) was prospectively evaluated to determine its ability to demonstrate vesicoureteral reflux (VUR) in children whose VCUG results were initially negative. The authors also assessed the effect of change in the patient's position on the detection of VUR. Seventy-seven children younger than 3 years of age, with negative results from a VCUG study performed while they were supine, underwent a second cycle of bladder filling after they were placed prone (group 1). Sixty-five children who were also younger than 3 years of age and had negative results from an initial VCUG examination performed in the usual supine position underwent a second cycle of bladder filling, which was also performed with the patient supine (group 2). VUR occurred in three children (4%) in group 1 and in eight (12%) in group 2. Most children (68.8%) in the two groups combined had grade II reflux. Cyclic VCUG increased detection of VUR, which led to a change in clinical treatment. Prone positioning did not enhance detection of VUR to the same degree as did multiple studies performed with the patient supine.     

Interactive magnetic resonance imaging for paediatric vesicoureteric reflux (VUR)

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.