Skip to main content
NCBI home page
Annals of Medicine logoLink to Annals of Medicine
. 2020 Jul 15;52(6):275–282. doi: 10.1080/07853890.2020.1741672

The diagnostic value of magnetic resonance urography for detecting ureteric obstruction: a systematic review and meta-analysis

Zhongping Chen 1,*, Huayu Huang 1,*, Jun Yang 1,*, Hongtao Cai 1,✉, Yali Yu 1
PMCID: PMC7877960  PMID: 32233669

Abstract

Objective

To evaluate the diagnostic accuracy of magnetic resonance urography (MRU) and determine its value for detecting ureteric obstruction.

Methods

The electronic databases, including PubMed, Embase and the Cochrane library, were systematically searched for studies published throughout September 2018. The summary of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR) and receiver operating characteristic (ROC) curves was assessed to evaluate the diagnostic accuracy of MRU. Subgroup analyses were conducted based on the mean age of the included patients (adults or children).

Results

Eight studies with a total of 594 patients were included. The summary of the sensitivity and specificity of MRU for diagnosing ureteric obstruction was 0.94 and 0.87, respectively. Furthermore, the pooled PLR and NLR were 7.33 and 0.07, respectively. The DOR of MRU for detecting ureteric obstruction was 95.12. In addition, the summary of the area under the ROC of MRU was 0.96. Finally, the specificity, PLR and area under the ROC of MRU for diagnosing ureteric obstruction in adults were higher than children, while the sensitivity of MRU in adults was lower than children.

Conclusions

These findings suggested a relatively high diagnostic value of MRU for detecting ureteric obstruction. Moreover, the diagnostic accuracy of MRU in adults was higher than in children.

KEY MESSAGE

  • Magnetic resonance urography (MRU) in detecting ureteric obstruction has relatively better sensitivity, specificity, PLR, NLR, DOR and AUC.

  • The diagnostic value, including specificity, PLR and AUC of MRU in adults, was higher than in children, while the sensitivity of MRU in adults was lower than in children.

Keywords: Ureter, systematic review, meta-analysis

Introduction

Obstructive uropathy is a common urologic presentation and a common cause of renal failure. Inadequate treatment for obstructive uropathy will lead to irreversible damage to renal parenchyma [1–3]. The management of obstructive uropathy is based on the precise delineation of reno-ureteral units and accurate estimation of the renal function. Currently, intravenous urography (IVU) combined with ultrasonography is widely used for the evaluation of obstructive uropathy in Asia [4]. However, the limitations of IVU include radiation exposure, contrast allergies, parenchymal visualization, and contraindicate pregnancy, renal failure, and diabetes. Furthermore, its sensitivity and specificity for detecting the cause of obstruction were not high.

The concept of magnetic resonance urography (MRU) was introduced at the end of the 1980s and was the first technique based on heavy T2-weighted images in clinical practice [5,6]. The technique of MRU is rapid and safe for the depiction of the urinary tract; it is also non-invasive when no Foley catheter is used. MRU is widely used in patients with obstructive uropathy and aims to determine the grade of dilation and location of the obstruction, but the correct identification of the underlying pathologic cause can be achieved in only 50% of the cases [7–9]. Most of the previous studies were designed as retrospective studies and with a small sample size, and hence the diagnostic accuracy of MRU varied. Therefore, this systematic review and meta-analysis was conducted to quantitatively assess the diagnostic efficacy of MRU to provide a better understanding regarding its diagnostic value in ureteric obstruction.

Materials and methods

Data sources, search strategy and selection criteria

Our present study was performed according to the guidelines of Preferred Reporting Items for Systematic reviews and Meta-Analyses [10]. We systematically searched the electronic databases, such as PubMed, Embase and the Cochrane library for relevant studies that investigated the diagnostic accuracy of MRU in detecting the ureteric obstruction and published up to September 2018. The core search term was combined with Medical Subject Headings and free terms of “magnetic resonance urography”. The published language was restricted to English only, while the publication status was not restricted. The reference lists from the retrieved studies and relevant reviews were manually searched. Studies published in letters, abstracts and conference proceedings are excluded.

Two reviewers independently reviewed the title and abstract of the article to select potentially eligible studies, and any disagreements between them are settled by a third author referring to the original article. The inclusion criteria are as follows: (1) patients: suspected with ureteric obstruction; (2) diagnostic tool: diagnosed using MRU; (3) outcomes: studies that provided sufficient data for reconstruction of a diagnostic 2*2 table including true positive, false positive, true negative and false negative; (4) study design: irrespective of study design, including prospective or retrospective studies.

Data collection and quality assessment

One author reviewed the full text and collected data items, and another author checked it. Any disagreement between them was resolved by discussion with each other until a consensus was reached. The collected items are as follows: first authors’ surname, publication year, country, sample size, mean age, number of men and women, type of MRU, patients status and number of true positive, false positive, true negative and false negative. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS), and each item was given a response of “yes”, “no” or “unclear” [11,12]. The answer of “yes” means that the risk of bias of the study is low, while “no” and “unclear” meant that the risk of bias can be judged as high or moderate.

Statistical analysis

The true positive, false positive, true negative and false negative were calculated after constructing the 2*2 tables in each study, and a continuity correction of 0.5 was added if 0 counts occurred in at least one cell of the study data [13–16]. The summary of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) was calculated using the bivariate binomial mixed model [17,18]. Moreover, the summary of the receiver operating characteristic (ROC) curve was also constructed based on the sensitivity and specificity values of the individual studies [19]. The area under the curve (AUC) of an SROC was employed as the diagnostic accuracy, and if the value was close to 1, it was regarded as excellent [20]. Heterogeneity across the included studies was evaluated using Cochran’s Q test and I-square, and p value <.10 was considered as significant heterogeneity [21–23]. Subgroup analyses were conducted based on adults or children. Deek’s funnel plot was conducted to evaluate for any potential publication bias [24]. p Values for pooled results are two-sided, and p<.05 was regarded as statistically significant. Statistical analyses were performed using STATA software (version 10.0; Stata Corporation, College Station, TX).

Results

Literature selection process

The detailed study selection process is presented in Figure 1. The initial literature search yielded 379 records, and 15 were excluded due to duplication of the topics. Moreover, after reading the titles and abstracts, 323 irrelevant topics were excluded. The remaining 41 studies were retrieved for further evaluations, where 33 studies were excluded due to the following reasons: published in another language (n = 7), diagnosed with other diseases (n = 21) and no sufficient data (n = 5). Finally, eight studies with 594 patients were included in the final meta-analysis [25–32]. A manual search of the reference lists from these studies did not yield any new eligible studies.

Figure 1.

Figure 1.

Open in a new tab

Flow diagram of literature search and trial selection process.

Characteristics and quality of the studies

The baseline characteristics of the included studies are shown in Table 1. Eight studies published between 1997 and 2008, and there were 40–149 patients included in each individual study. Three studies were conducted in the USA [25, 29, 31], three in Europe [26–28] and the remaining two in Egypt and Iran [30, 32]. Five studies included adult patients, and the remaining three studies included children. The quality of the studies was evaluated using QUADAS, and the details of each item are presented in Table 2.

Table 1.

Characteristics of the studies included in the meta-analysis.

Author Publication year Country N Mean age (years) Male/female Type of MRU (gold standard) Patients status TP (N) FP (N) FN (N) TN (N)
Regan et al. [25] 1997 USA 55 48.0 40/15 TR = 8.2, TE = 66, single excitation and a slice thickness of 4–6 mm (IVU or CT) Patients with suspected ureteric obstruction 20 3 3 15
Jung et al. [26] 2000 Germany 82 56.0 51/31 Gyroscan ACS-NT, Philips. TR = 2900, TE = 700, section thickness 60–80 mm, excretory phase (IVU first; if inconclusive: CT, retrograde pyelography or ureteroscopy) Clear cause for ureteric obstruction or a suspected abnormality of the upper urinary tract 35 4 3 30
Sudah et al. [27] 2001 Finland 40 51.0 32/8 Magnetom Vision; Siemens. TR = 4.6, TE = 1.8, slice thickness 1.75 mm, excretory phase (excretory urography and final clinical diagnosis) Acute flank pain symptoms 25 1 0 14
Rohrschneider et al. [28] 2002 Germany 74 1.0 47/27 Philips Medical Systems. TR = 3500, TE = 600 (diuretic renal scintigraphy) Congenital urinary tract dilatation 23 14 0 30
Grattan-Smith et al. [29] 2003 USA 40 1.4 26/14 Spin echo T1 and fat-suppressed fast spin echo T2 images (traditional imaging modalities) Unilateral hydronephrosis 25 4 0 10
Shokeir et al. [30] 2004 Egypt 149 51.0 99/40 Signa Horizon LX, EchoSpeed, without details (retrograde or anterograde ureterogram, ureteroscopy and/or open surgery) Compromised renal function 101 6 12 140
Regan et al. [31] 2005 USA 64 NA NA TR = 2000, TE = 80, single excitation and a slice thickness of 10 mm (CT) Suspected acute calculus ureteric obstruction 41 1 3 19
Payabvash et al. [32] 2008 Iran 90 2.3 61/29 Gyroscan, Philips Medical Systems, excretory phase, without details about the sequences (ultrasound, IVU, renal nuclide scan and voiding cystourethrography) Suspected urinary system pathology 21 9 4 56
Open in a new tab

TP: true positive; FP: false positive; TN: true negative; FN: false negative; NA: not available; IVU: intravenous urography; CT: computed tomography.

Table 2.

Quality evaluation of the included studies using the QUADAS tool.

Study Question about study design characteristic
Representative patient spectrum Reporting of selection criteria Reference standard Absence of disease progression bias Absence of partial verification bias Absence of differential verification bias Absence of incorporation bias Description of index text execution Description of reference standard execution Reference standard blinded Index test blinded Absence of clinical review bias Reporting of uninterpretable/ intermediate results Withdrawal
Regan Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Jung Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Sudah Yes NA Yes Yes Yes NA Yes Yes Yes Yes Yes NA Yes Yes
Rohrschneider Yes NA Yes Yes Yes NA Yes Yes Yes Yes Yes NA Yes Yes
Grattan-Smith Yes NA Yes Yes Yes NA Yes Yes Yes Yes Yes NA Yes Yes
Shokeir Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Regan Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Payabvash Yes Yes Yes Yes Yes NA Yes Yes Yes Yes Yes NA Yes Yes
Open in a new tab

Sensitivity and specificity

The sensitivity of MRU for detecting ureteric obstruction ranged from 0.84 to 1.00, and the specificity ranged from 0.68 to 0.96 across the included studies. The summary of sensitivity and specificity was 0.94 (95%CI: 0.89–0.97) and 0.87 (95%CI: 0.79–0.93), respectively (Figure 2). Subgroup analyses indicated that the sensitivity of MRU in adults was lower than that of the children (ratio: 0.94; 95%CI: 0.88–1.00; p=.041), while the specificity of MRU in adults was higher than the children (ratio: 1.21; 95%CI: 1.01–1.45; p=.040; Table 3).

Figure 2.

Figure 2.

Open in a new tab

The summary of sensitivity and specificity of MRU for detecting ureteric obstruction.

Table 3.

Subgroup analyses of diagnostic value according to mean age.

Variable Group Effect estimate and 95%CI Ratio of effect estimate and 95%CI p Value for interaction test
Sensitivity Adults 0.92 (0.87–0.95) 0.94 (0.88–1.00) .041
Children 0.98 (0.92–1.00)
Specificity Adults 0.93 (0.87–0.96) 1.21 (1.01–1.45) .040
Children 0.77 (0.65–0.92)
PLR Adults 12.97 (6.98–24.07) 3.40 (1.59–7.24) .002
Children 3.82 (2.47–5.91)
NLR Adults 0.09 (0.06–0.14) 1.29 (0.32–5.14) .722
Children 0.07 (0.02–0.28)
DOR Adults 131.10 (62.29–275.91) 2.89 (0.77–10.81) .115
Children 45.40 (15.27–135.00)
SROC Adults 0.96 (0.93–0.97) 1.07 (1.03–1.10) <.001
Children 0.90 (0.87–0.92)
Open in a new tab

Positive and negative likelihood ratio

The PLR of MRU for detecting ureteric obstruction ranged from 3.04 to 21.75, and NLR ranged from 0.02 to 0.19 across the included studies. The summary of PLR and NLR was 7.33 (95%CI: 4.38–12.25) and 0.07 (95%CI: 0.04–0.13), respectively (Figure 3). Subgroup analyses indicated that the PLR of MRU in adults was significantly higher than children (ratio: 3.40; 95%CI: 1.59–7.24; p=.002), while no significant difference was observed between adults and children for NLR (ratio: 1.29; 95%CI: 0.32–5.14; p=.722; Table 3).

Figure 3.

Figure 3.

Open in a new tab

The summary of positive and negative likelihood ratios of MRU for detecting ureteric obstruction.

Diagnostic odds ratio

The DOR of MRU for diagnosing ureteric obstruction ranged from 32.67 to 493.00 across the included studies. The pooled DOR of MRU for detecting ureteric obstruction was 95.12 (95%CI: 49.69–182.08; p<.001; Figure 4), and an unimportant heterogeneity was observed (I-square: 10.0%; p=.353). There was no significant difference between adults and children for the DOR of MRU (ratio: 2.89; 95%CI: 0.77–10.81; p=.115; Table 3).

Figure 4.

Figure 4.

Open in a new tab

The summary of diagnostic odds ratio of MRU for detecting ureteric obstruction.

Summary receiver operating characteristic curve

The summary of the ROC curve was calculated, and the AUC was 0.96 (95%CI: 0.94–0.98) for MRU detection of ureteric obstruction (Figure 5). Subgroup analysis indicated that the AUC in adults was significantly higher than children (ratio: 1.07; 95%CI: 1.03–1.10; p<.001; Table 3).

Figure 5.

Figure 5.

Open in a new tab

The summary of receiver operating characteristic curve of MRU for detecting ureteric obstruction.

Publication bias

Publication bias was calculated according to Deek’s funnel plot, and no significant publication bias of MRU for diagnosing ureteric obstruction was observed (p=.47; Figure 6).

Figure 6.

Figure 6.

Open in a new tab

Publication bias of MRU for detecting ureteric obstruction.

Discussion

The current meta-analysis evaluated the diagnostic accuracy of MRU for detecting ureteric obstruction, and most of the included studies were of high or moderate methodological quality. This quantitative meta-analysis recruited 594 patients from eight studies with a broad range of patient characteristics. The results of this study indicated that MRU had a relatively high sensitivity, specificity, PLR, NLR, DOR and AUC for diagnosing ureteric obstruction. Moreover, we noted that the summary of specificity, PLR and AUC of MRU for detecting a ureteric obstruction in adults was significantly higher than children, but the sensitivity of MRU for diagnosing ureteric obstruction in adults was lower than children.

This is the first meta-analysis study to determine the diagnostic accuracy of MRU for detecting ureteric obstruction and stratified the pooled effect estimates according to adults and children. Nevertheless, there was wide variability among the included studies in terms of diagnostic methods and the gold standard. Indeed, Regan et al. indicated that half-Fourier acquisition single-shot turbo spin-echo (HASTE) MR has accurately diagnosed (87%) the presence of acute ureteric obstruction and HASTE MR could accurately distinguish acute and chronic ureteric obstructions according to the degree of perirenal high signal intensities [25]. Jung et al. found that MRU enhanced with gadolinium, and frusemide was useful for dilating the system with no excretory function in pregnant women, children or individuals allergic to contrast medium [26]. Sudah et al. indicated that T2-weighted sequences were not associated with sufficient diagnostic value for patients with acute flank pain, while the combined use of T2-weighted and 3D fast low-angle shot sequences provided better profiles for evaluating acute suspected renal colic [27]. Shokeir et al. concluded that noncontrast computerized tomography has good diagnostic accuracy for detecting the causes of calculous obstruction, and MRU demonstrated better diagnostic accuracy for detecting noncalculous lesions in patients with renal impairment due to ureteral obstruction [30]. Regan et al. found that the sensitivity, specificity and accuracy of the combination of fluid and ureteric dilation on MRU were 93%, 95% and 94%, respectively [31]. When taken together, those studies suggest the higher diagnostic value of MRU in adults for detecting ureteric obstructions.

Three studies reported the diagnostic value of MRU in children. Rohrschneider et al. suggested that the combination of static–dynamic MRU provides good diagnostic value for the urinary tract in infants and children [28]. Grattan-Smith et al. included 14 girls and 26 boys with an age range of 1 month to 14 years to assess the diagnostic value of MRU for detecting ureteric obstructions. The results pointed out that the sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy to be 100%, 71%, 86%, 100% and 90%, respectively [29]. Payabvash et al. reported a greater advantage of MRU over conventional excretory urography or radionuclide renography for diagnosing ureteric obstructions [32]. The differences between adults and children for sensitivity, specificity, PLR and SROC could be biases of the inclusion of a single study. The reason could be that MRU has a high ability to detect a wide range of urogenital anomalies.

However, there are several limitations of this meta-analysis that needs to be highlighted: (1) the data collected for the extent of ureteric obstruction were not available, restricting the practices of this study; (2) the sources of heterogeneity cannot be fully interpreted by subgroups as most of the studies did not report the patient characteristics; (3) study design and sample size might affect the reliability of summary results; (4) the analysis was based on pooled data, which restricted the stratified analyses according to more detailed characteristics.

The findings of this meta-analysis suggested MRU in detecting ureteric obstruction has relatively good sensitivity, specificity, PLR, NLR, DOR and AUC. Moreover, the diagnostic value, including specificity, PLR and AUC of MRU in adults was higher than in children, while the sensitivity of MRU in adults was lower than in children. Future studies should be conducted to compare the diagnostic value of MRU with other diagnostic tools in diagnosing ureteric obstructions.

Funding Statement

This study was supported by the Shenzhen Longhua District Technology Innovation Fund (20150617A1030055).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, [HTC], upon reasonable request.

References

  • 1.Garne E, Loane M, Wellesley D, et al. Congenital hydronephrosis: prenatal diagnosis and epidemiology in Europe. J Pediatr Urol. 2009;5(1):47–52. [DOI] [PubMed] [Google Scholar]
  • 2.O’Reilly P, Aurell M, Britton K, et al. Consensus on diuresis renography for investigating the dilated upper urinary tract. Radionuclides in Nephrourology Group. Consensus Committee on Diuresis Renography. J Nucl Med. 1996;37(11):1872–1876. [PubMed] [Google Scholar]
  • 3.Podevin G, Mandelbrot L, Vuillard E, et al. Outcome of urological abnormalities prenatally diagnosed by ultrasound. Fetal Diagn Ther. 1996;11(3):181–190. [DOI] [PubMed] [Google Scholar]
  • 4.Nishiyama H. Asia Consensus Statement on NCCN Clinical Practice Guideline for bladder cancer. Jpn J Clin Oncol. 2018;48(1):3–6. [DOI] [PubMed] [Google Scholar]
  • 5.Hennig J, Nauerth A, Friedburg H.. RARE imaging: a fast imaging method for clinical MR. Magn Reson Med. 1986;3(6):823–833. [DOI] [PubMed] [Google Scholar]
  • 6.Hennig J, Friedburg H.. Clinical applications and methodological developments of the RARE technique. Magn Reson Imaging. 1988;6(4):391–395. [DOI] [PubMed] [Google Scholar]
  • 7.Louca G, Liberopoulos K, Fidas A, et al. MR urography in the diagnosis of urinary tract obstruction. Eur Urol. 1999;35(2):102–108. [DOI] [PubMed] [Google Scholar]
  • 8.Hussain S, O'Malley M, Jara H, et al. MR urography. Magn Reson Imaging Clin N Am. 1997;5(1):95–106. [PubMed] [Google Scholar]
  • 9.O’Malley ME, Soto JA, Yucel EK, et al. MR urography: evaluation of a three-dimensional fast spin-echo technique in patients with hydronephrosis. AJR Am J Roentgenol. 1997;168(2):387–392. [DOI] [PubMed] [Google Scholar]
  • 10.Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6(7):e1000097. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11.Whiting P, Rutjes AW, Reitsma JB, et al. The development of QUADAS: a tool for the quality assessment of studies of diagnostic accuracy included in systematic reviews. BMC Med Res Methodol. 2003;3(1):25. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12.Whiting PF, Weswood ME, Rutjes AW, et al. Evaluation of QUADAS, a tool for the quality assessment of diagnostic accuracy studies. BMC Med Res Methodol. 2006;6:9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 13.Friedrich JO, Adhikari NKJ, Beyene J.. Inclusion of zero total event trials in meta-analyses maintains analytic consistency and incorporates all available data. BMC Med Res Methodol. 2007;7(1):5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Cox DR. The design of empirical studies: towards a unified view. Eur J Epidemiol. 2016;31(3):217–228. [DOI] [PubMed] [Google Scholar]
  • 15.Bow EJ, Laverdière M, Lussier N, et al. Antifungal prophylaxis for severely neutropenic chemotherapy recipients: a meta analysis of randomized-controlled clinical trials. Cancer. 2002;94(12):3230–3246. [DOI] [PubMed] [Google Scholar]
  • 16.Cook DJ, Witt LG, Cook RJ, et al. Stress ulcer prophylaxis in the critically ill: a meta-analysis. Am J Med. 1991;91(5):519–527. [DOI] [PubMed] [Google Scholar]
  • 17.Zamora J, Abraira V, Muriel A, et al. Meta-DiSc: a software for meta-analysis of test accuracy data. BMC Med Res Methodol. 2006;6(1):31. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18.DerSimonian R, Laird N.. Meta-analysis in clinical trials. Control Clin Trials. 1986;7(3):177–188. [DOI] [PubMed] [Google Scholar]
  • 19.Moses LE, Shapiro D, Littenberg B.. Combining independent studies of a diagnostic test into a summary ROC curve: data-analytic approaches and some additional considerations. Stat Med. 1993;12(14):1293–1316. [DOI] [PubMed] [Google Scholar]
  • 20.Hanley JA, McNeil BJ.. The meaning and use of the area under a receiver operating characteristic (ROC) curve. Radiology. 1982;143(1):29–36. [DOI] [PubMed] [Google Scholar]
  • 21.Higgins JP, Thompson SG, Deeks JJ, et al. Measuring inconsistency in meta-analyses. BMJ. 2003;327(7414):557–560. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22.Deeks JJ. Systematic reviews in health care: systematic reviews of evaluations of diagnostic and screening tests. BMJ. 2001;323(7305):157–162. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23.Deeks JJ, Higgins JPT, Altman DG.. Analyzing data and undertaking meta-analyses. Oxford (UK): The Cochrane Collaboration; 2008. [Google Scholar]
  • 24.Deeks JJ, Macaskill P, Irwig L.. The performance of tests of publication bias and other sample size effects in systematic reviews of diagnostic test accuracy was assessed. J Clin Epidemiol. 2005;58(9):882–893. [DOI] [PubMed] [Google Scholar]
  • 25.Regan F, Petronis J, Bohlman M, et al. Perirenal MR high signal – a new and sensitive indicator of acute ureteric obstruction. Clin Radiol. 1997;52(6):445–450. [DOI] [PubMed] [Google Scholar]
  • 26.Jung P, Brauers A, Nolte-Ernsting CA, et al. Magnetic resonance urography enhanced by gadolinium and diuretics: a comparison with conventional urography in diagnosing the cause of ureteric obstruction. BJU Int. 2001;86(9):960–965. [DOI] [PubMed] [Google Scholar]
  • 27.Sudah M, Vanninen R, Partanen K, et al. MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot. AJR Am J Roentgenol. 2001;176(1):105–112. [DOI] [PubMed] [Google Scholar]
  • 28.Rohrschneider WK, Haufe S, Wiesel M, et al. Functional and morphologic evaluation of congenital urinary tract dilatation by using combined static-dynamic MR urography: findings in kidneys with a single collecting system. Radiology. 2002;224(3):683–694. [DOI] [PubMed] [Google Scholar]
  • 29.Grattan-Smith JD, Perez-Bayfield MR, Jones RA, et al. MR imaging of kidneys: functional evaluation using F-15 perfusion imaging. Pediatr Radiol. 2003;33(5):293–304. [DOI] [PubMed] [Google Scholar]
  • 30.Shokeir AA, El-Diasty T, Eassa W, et al. Diagnosis of ureteral obstruction in patients with compromised renal function: the role of noninvasive imaging modalities. J Urol. 2004;171(6 Part 1):2303–2306. [DOI] [PubMed] [Google Scholar]
  • 31.Regan F, Kuszyk B, Bohlman ME, et al. Acute ureteric calculus obstruction: unenhanced spiral CT versus HASTE MR urography and abdominal radiograph. Br J Radiol. 2005;78(930):506–511. [DOI] [PubMed] [Google Scholar]
  • 32.Payabvash S, Kajbafzadeh AM, Saeedi P, et al. Application of magnetic resonance urography in diagnosis of congenital urogenital anomalies in children. Pediatr Surg Int. 2008;24(9):979–986. [DOI] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author, [HTC], upon reasonable request.

Articles from Annals of Medicine are provided here courtesy of Taylor & Francis

RESOURCES