Magnetic resonance urography enhanced by gadolinium and diuretics: a comparison with conventional urography in diagnosing the cause of ureteric obstruction

Ultrasound findings and clinical characteristics in differentiating renal urothelial carcinoma from endophytic clear cell renal cell carcinoma

OBJECTIVE

This study aimed to evaluate the clinical characteristics and features of conventional ultrasound (CUS) and contrast-enhanced ultrasound (CEUS) in differentiating between renal urothelial carcinomas (RUC) and endophytic clear cell renal cell carcinomas (EccRCC).

METHODS

A total of 72 RUCs and 120 EccRCCs confirmed by pathology were assessed retrospectively. Both CUS and CEUS were performed within 4 weeks before the surgery. Logistic regression analyses were used to select statistically significant variables of clinical, CUS, and CEUS features for the differentiation of RUC and EccRCC. Sensitivity (SEN), specificity (SPE), and the area under the receiver-operating characteristic curve (AUC) were assessed for diagnostic performance. Inter- and intra-observer agreements of CUS and CEUS features were evaluated using the intra-class correlation coefficient(ICC).

RESULTS

Multiple logistic regression analysis demonstrated that clinical (age >50 years old and hematuria), CUS (size <4.0 cm, hypo-echogenicity, irregular shape, hydronephrosis) and CEUS (absence of non-enhancement area, iso- /hypo-enhancement in cortical phase and absence of rim-like enhancement) features were independent factors for RUC diagnosis. When combining clinical characters with CUS and CEUS features into an integrated diagnostic criterion, the AUC reached 0.917 (95% CI 0.873-0.961), with a sensitivity of 95.8% and specificity of 87.5%. ICC ranged from 0.756 to 0.907 for inter-observer agreement and 0.791 to 0.934 for intra-observer agreement for CUS and CEUSfeatures.

CONCLUSIONS

The combination of clinical features of age and hematuria with imaging features of CUS and CEUS can be useful for the differentiation between RUC and EccRCC.

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

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.

Value of Magnetic Resonance Urography Versus Computerized Tomography Urography (CTU) in Evaluation of Obstructive Uropathy: An Observational Study

BACKGROUND

Obstructive uropathy is a common public health issue that requires imaging research for providing necessary information. The data is important for determining treatment options, and may influence selective management choices.

OBJECTIVE

The aim of the study is to determine whether magnetic resonance urography or computerized tomography urography is the best imaging modality among patients with suspected obstructive uropathy.

METHODS

Seventy patients; referred from the emergency department for the evaluation of renal colic or hematuria that highly suggested urinary tract abnormalities, were prospectively enrolled. Thirty five women and 35 men were categorized with a mean age of 43.52 years and the mean body weight of 61.31 kg. All participants underwent abdominal ultrasonography and clinical examination to detect the causes of urinary obstruction. Pregnant women were excluded from the study. Both magnetic resonance urography and computerized tomography urography were performed within 30 days of each analysis.

RESULTS

Only 54.3% of the participants had urinary stones. Mean size of the renal stone was 11 mm; while mean size of the ureteral stone was 3.8 mm. The approach of magnetic resonance is not only limited to diagnosis, but is also effectively involved in the real time investigations. MRU has more reliability in terms of the diagnosis and anatomic presentation of the kidneys along with the vasculature. All cases of urinary stones were detected by computed tomography (100%); whereas, 78.9% cases were detected by magnetic resonance urography.

CONCLUSION

Computerized tomography urography is more sensitive in detecting kidney stones; whereas, magnetic resonance urography is better in detecting pathology behind the development of kidney stones.

Imaging in the diagnosis of pediatric urolithiasis

Pediatric urolithiasis is an important and increasingly prevalent cause of pediatric morbidity and hospital admission. Ultrasound (US) is the recommended primary imaging modality for suspected urolithiasis in children. There is, however, widespread use of CT as a first-line study for abdominal pain in many institutions involved in pediatric care. The objective of this review is to outline state-of-the-art imaging modalities and methods for diagnosing urolithiasis in children. The pediatric radiologist plays a key role in ensuring that the appropriate imaging modality is performed in the setting of suspected pediatric urolithiasis. Our proposed imaging algorithm starts with US, and describes the optimal technique and indications for the use of CT. We emphasize the importance of improved communication with a greater collaborative approach between pediatric and general radiology departments so children undergo the appropriate imaging evaluation.

Follow-up in non-muscle-invasive bladder cancer-International Bladder Cancer Network recommendations

OBJECTIVE

Non-muscle-invasive bladder cancer (NMIBC) comprises a wide spectrum of tumors with different behaviors and prognoses. It follows that the surveillance for these tumors should be adapted according to the risks of recurrence and progression and should be dynamic in design.

METHODS AND MATERIALS

Medline search was conducted from 1980 to 2016 using a combination of MeSH and keyword terms. The highest available evidence was reviewed to define different risk groups in NMIBC. The performance of different follow-up tools such as urine cytology, cystoscopy, and upper tract imaging in detecting bladder carcinoma was assessed. Different commercially available urinary markers were investigated to determine whether such markers would contribute to the surveillance of patients with NMIBC. A follow-up scheme based on the early evidence is proposed.

RESULTS

A risk-based approach is paramount. Cystoscopy and cytology are recommended to be done at 3 months following transurethral resection of bladder tumor. For low-risk tumors, annual cystoscopy alone is sufficient; no upper tract evaluations or cytology is needed except at diagnosis. High-risk tumors should be followed up with a more intense schedule: cystoscopy every 3 months for 2 years, 6 months for 2 years, and then annually, with cytology at frequent intervals, and imaging for upper tract evaluation at 1 year and then every 2 years. Intermediate-risk tumors should be subclassified as per the International Bladder Cancer Group recommendations and when associated with 3 or more of the following findings (multiple tumors, size≥3cm, early recurrence<1 year, frequent recurrences>1 per year) then a surveillance strategy similar to that of high risk should be followed. Several urine markers were more sensitive than cytology in the detection of NMIBC; however, these tests are still costly, require specialized laboratories, and do not replace cystoscopy. Until better and cheaper markers are available, their routine use has not been integrated in the follow-up recommendation of current guidelines.

CONCLUSIONS

Surveillance of NMIBC should follow a risk-adapted approach, with a combination of cystoscopy, cytology, and upper tract imaging. The aim of this approach is to minimize the therapeutic burden of a disease with high recurrence rates without missing progressing tumors. When designing a diagnostic pathway, first-line diagnostic imaging tests should have high sensitivity to ensure disease positives are included in the test population for further investigation. Second-line investigations should be highly specific, to ensure false-positives are minimized.

Trends in the utilization of imaging for upper tract urothelial carcinoma

OBJECTIVES

To evaluate the changes in use of the different imaging modalities for diagnosing upper tract urothelial carcinoma (UTUC) and assess how these changes have affected tumor stage at the time of surgery.

MATERIALS AND METHODS

We assessed the Surveillance, Epidemiology, and End Results (SEER) cancer registry and linked Medicare claims data (1992-2009) for 5377 patients who underwent surgery for UTUC. We utilized International Classification of Disease-Oncology 3 codes to identify UTUC. International Classification of Disease, ninth Revision, Clinical Modification and Current Procedure Terminology codes identified surgical treatment and imaging modalities. We assessed for use of intravenous pyelography, retrograde pyelography (RGP), computed tomography urography (CTU), magnetic resonance urography (MRU), and endoscopy. For each modality, patients were categorized as having received the modality at least once or not at all. Patient characteristics were compared using chi-squared tests. Usage of imaging modalities and tumor stage was trended using Cochran-Armitage tests. We stratified our data into 2 multivariate logistic regression models to determine the effect of imaging modalities on tumor stage: 1992 to 1999 with all modalities except MRU, and 2000 to 2009 with all modalities.

RESULTS

Our patient population was predominantly White males of more than 70 years old. Intravenous pyelography and RGP declined in use (62% and 72% in 1992 vs. 6% and 58% in 2009, respectively) while computed tomography urography, MRU, and endoscopy increased in use (2%, 0%, and 37% in 1992 vs. 44%, 6%, and 66% in 2009, respectively). In both regression analyses, endoscopy was associated with lower-stage tumors. In the 2000 to 2009 model, RGP was associated with lower-stage tumors, and MRU was associated with higher-stage tumors. Finally, our data showed an increasing number of modalities utilized for each patient (1% receiving 4 modalities in 1992 vs. 20% in 2009).

CONCLUSIONS

We found trends toward the utilization of newer imaging modalities to diagnose UTUC and more modalities per patient. Endoscopy and RGP were associated with smaller tumors, whereas MRU was associated with larger tumors. Further studies are needed to evaluate the utility of the different modalities in diagnosing UTUC.

Magnetic resonance urography vs computed tomography urography in the evaluation of patients with haematuria

PURPOSE

This study was done to evaluate by direct comparison the image quality of magnetic resonance urography (MRU) and computed tomography urography (CTU) and to assess the diagnostic confidence of the two techniques in detecting urothelial malignancy in patients with haematuria

MATERIALS AND METHODS

Thirty-five patients with haematuria underwent both CTU and MRU. Two different investigators evaluated calyceal, renal pelvis, ureteral and bladder visibility. Their diagnostic confidence in detecting urothelial malignancy with the two procedures was assessed. A Wilcoxon matched-pairs test was performed to compare results. Inter-reader agreement was calculated by weighted kappa (WK) statistic. Patient history (further examinations, cystoscopy and histological specimens) was considered as reference standard to calculate receiver operating characteristic (ROC) curves of diagnostic confidence.

RESULTS

CTU provided better visibility of urothelial structures (p<0.01) and allowed for greater diagnostic confidence (ROC area 0.994 vs. 0.938) than MRU, with a good inter-reader agreement (WK=0.62). Nevertheless, in obstructive patients with impaired excretory function, MRU, thanks to the static-fluid technique, offered better visualisation than CTU.

CONCLUSIONS

There is a potential role for MRU in urinary tract imaging, but as diagnostic confidence in detecting urothelial malignancy is poorer than in CTU, it might be stareserved for patients at low risk for malignancy and for evaluating obstructed patients.

Usefulness of diffusion-weighted MRI in diagnosis of upper urinary tract cancer

OBJECTIVE

The purpose of this study was to prospectively evaluate the diagnostic ability of diffusion-weighted MRI (DWI) for detecting upper urinary tract cancer.

SUBJECTS AND METHODS

Seventy-six patients (36 women, 40 men; median age, 70 years) suspected of having upper urinary tract cancer underwent T1- and T2-weighted imaging and DWI (b values, 0 and 800 s/mm(2)) with or without T1-weighted dynamic contrast-enhanced MRI (DCE-MRI). Two radiologists independently interpreted the images.

RESULTS

Of the 76 patients suspected of having upper urinary tract cancer, 49 were diagnosed with upper urinary tract cancer and the remaining 27 were diagnosed as not having upper urinary tract cancer. The sensitivity, specificity, and accuracy of DWI interpretation for each reviewer was 92%, 96%, and 93% and 94%, 81%, and 89%, respectively. The sensitivity and accuracy of DWI were significantly higher than those of T1- and T2-weighted imaging (p < 0.01 and p = 0.03 for reviewer 1 and p < 0.01 for both values for reviewer 2), although the specificity did not change. The diagnostic abilities of DWI and DCE-MRI were not significantly different. The interobserver agreement of DWI between the two reviewers was excellent (κ score = 0.801). The apparent diffusion coefficient values of upper urinary tract cancer with grade 3 were significantly lower than those of upper urinary tract cancer with grades 2 and 1 (p < 0.028).

CONCLUSION

DWI provides accurate information for the diagnosis of upper urinary tract cancer in a noninvasive manner. The additional use of DWI to T1- and T2-weighted imaging increases the sensitivity of MRI in identifying upper urinary tract cancer with excellent interobserver agreement. Furthermore, DWI could be a useful adjunct to preoperative assessment of histologic grade.

MR urography versus retrograde pyelography/ureteroscopy for the exclusion of upper urinary tract malignancy

AIM

To evaluate the diagnostic performance of magnetic resonance urography (MRU) versus retrograde pyelography and/or ureteroscopy (RPU) in the detection of upper urinary tract neoplasms.

MATERIALS AND METHODS

This retrospective study included 35 patients with suspected upper urinary tract malignancy who underwent MRU and RPU within 6-months in our institution during the study period (February 2002 to January 2007). MRU and RPU reports were reviewed and results recorded. For each patient, the urinary tract was sub-divided into four regions for analysis: left kidney/renal pelvis, left ureter, right kidney/renal pelvis, and right ureter. MRU and RPU results for each patient were compared to a reference standard and the diagnostic performance of both techniques was compared.

RESULTS

A total of 113 regions were analysed on MRU and 90 regions on RPU. Nineteen neoplasms were identified. Sensitivity, specificity, positive predictive value, and negative predictive value for the detection of urinary tract neoplasms were 63, 91, 60, and 92% for MRU, respectively, and 53, 97, 83, and 88% for RPU, respectively. These differences were not statistically significant (p>0.05).

CONCLUSION

The high negative predictive value of MRU in the present series supports its use as a non-invasive screening examination for excluding the presence of upper urinary tract malignancy.

Role of magnetic resonance urography in diagnosis of duplex renal system: Our initial experience at a tertiary care institute

Aim:

To determine diagnostic value of magnetic resonance urography in cases of duplex renal system.

Method:

Twenty cases between five month to nine years with suspected or known duplex renal system were evaluated by ultrasound (USG), micturating cystourethrography (MCU), intravenous urography (IVU) and magnetic resonance urography (MRU). The findings of these diagnostic imaging studies were then compared with each other and against the results of final diagnosis established at surgery.

Results:

Duplex renal system could be identified in two of these cases on USG, was diagnosed in four in IVU and could be diagnosed in all cases with MRU.

Conclusion:

MRU is superior and far accurate than IVU, MCU and USG in diagnosing duplex renal system.

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.

Imaging modalities for urolithiasis: impact on management

PURPOSE OF REVIEW

Urolithiasis is a common urological problem, often requiring efficient workup, accurate diagnosis, and treatment. The purpose of this review is to summarize the imaging modalities employed for the diagnosis of calculi and the caveats of different clinical situations.

RECENT FINDINGS

Noncontrast computed tomography has become the most universally used imaging tool for diagnosing urolithiasis, although ultrasound and magnetic resonance imaging maintain specific roles. Noncontrast computed tomography may provide prognostic information regarding the success of specific management strategies for urolithiasis. Additionally, noncontrast computed tomography is being tested in lower-radiation dose protocols with promising results.

SUMMARY

Considering the well supported accuracy and relative ease of use of noncontrast computed tomography, it has become a logical choice for the urologist to use the technique as a diagnostic tool for stone disease. The future of imaging for intervention and surveillance of stone disease lies in the continued progress of noncontrast computed tomography in terms of patient safety. This will need to be done by developing low-dose radiation computed tomography that can replicate the efficacy of current noncontrast computed tomography.

MR urography: techniques and clinical applications

Magnetic resonance (MR) urography comprises an evolving group of techniques with the potential for allowing optimal noninvasive evaluation of many abnormalities of the urinary tract. MR urography is clinically useful in the evaluation of suspected urinary tract obstruction, hematuria, and congenital anomalies, as well as surgically altered anatomy, and can be particularly beneficial in pediatric or pregnant patients or when ionizing radiation is to be avoided. The most common MR urographic techniques for displaying the urinary tract can be divided into two categories: static-fluid MR urography and excretory MR urography. Static-fluid MR urography makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MR urography) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenoses, and is most successful in patients with dilated or obstructed collecting systems. Excretory MR urography is performed during the excretory phase of enhancement after the intravenous administration of gadolinium-based contrast material; thus, the patient must have sufficient renal function to allow the excretion and even distribution of the contrast material. Diuretic administration is an important adjunct to excretory MR urography, which can better demonstrate nondilated systems. Static-fluid and excretory MR urography can be combined with conventional MR imaging for comprehensive evaluation of the urinary tract. The successful interpretation of MR urographic examinations requires familiarity with the many pitfalls and artifacts that can be encountered with these techniques.

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.

Does a full bladder aid upper tract visualization in magnetic resonance urography?

The aim of this study was to evaluate whether a full bladder improved the visualization of the upper renal tract during magnetic resonance urography (MRU). Twenty volunteers were recruited into the study. The MRU imaging was carried out on a 1.5-T MR system. Imaging was carried out in the coronal plane using a half-Fourier acquired single-shot turbo-spin-echo technique. All volunteers were examined in two separate MRU studies to visualize the urinary tract. The first study was carried out with a 'full' bladder followed by a study with an 'empty' bladder, leading to a total of 40 examinations. Two radiologists then reviewed maximum intensity projection images from both 'full' and 'empty' studies independently. Both left and right upper tracts were divided into five segments. A three-point grading system was used to evaluate visualization. Excellent visualization = 3, good visualization = 2 and poor visualization = 1. Maximum score per patient was 30. Results were tabulated and analysed using an Excel database. The average score for visualization for the 'full' bladder group was 22.1/30 (73.8%) and the average score for the empty bladder was 16.2/30 (54%). Overall improvement in visualization was 5.9/30 (19.8%). There was strong interobserver agreement, with a concordance value of 92.5%. The MRU carried out in healthy young adult volunteers with a full bladder allows improved visualization of the upper tracts.

Uso de la urografía por resonancia magnética en el estudio del aparato urinario frente a la urografía convencional

Conventional urography (IVU) is an essential examination for the assessment of urinary tract but it is not free of complications, such as adverse reactions to contrast agents used (vasovagal and anaphylactic reactions), neurotoxicity, nephrotoxicity, as well as the damage due to the ionizing irradiation applied to the patient. For this reason, alternative imaging techniques such as magnetic resonance (MR) urography or uro-resonance have been developed.

OBJECTIVE

We present a case study assessing the diagnostic accuracy, specificity and sensitivity of uro-resonance and IVU as a morphological and functional examination of the urinary tract: and a quality study of the urographic images obtained with MR versus IVU.

MATERIALS AND METHODS

150 patients have submited to a MR study, 63 of them with an IVU study already performed, acquiring high-intensity signals at T2 corresponding to abdominal and retroperitoneal fluid, initially using furosemide at low doses and, in a final study, administering gadolinium at a rate of 0.1 mg/Kg. The test was indicated in patients with antecedents of adverse reactions to iodine contrast, acute or chronic kidney failure, functional cancellation of the kidneys, pregnant patients and those in paediatric age. The capacity of diagnosis of urinary obstruction and the aetiology of this obstruction of both tests was studied, as well as the quality of the images obtained by the urographic study using MR.

RESULTS

High resolution images were obtained of all the upper urinary tracts using MR, especially in the renal pelvis, without artefacts caused by peristalsis or intestinal fluid interposition. In 83.3% of cases, examinations revealed urological pathology. The diagnostic accuracy of the involvement cause of the urinary tract was 83.3%, with a sensitivity of 89.6%, a specificity of 69.2%. a positive predictive value of 86.6% and a negative predictive value of 75%.

CONCLUSION

MR urography is a high sensitive technique for the study of urinary tract, used as an alternative to conventional urography particularly in cases of the contraindication of ionizing radiation or allergy to the contrast agent, as well as in patients with renal failure, and offers a wider morphological and functional study, with a high image quality, able to displace conventional examinations in the short or medium term.

The role of magnetic resonance imaging in pediatric urology

PURPOSE OF REVIEW

Magnetic resonance imaging has emerged as a powerful diagnostic tool for the imaging of the pediatric genitourinary tract. The aim of this review is to familiarize the reader with the current applications and basic techniques utilizing magnetic resonance imaging in pediatric uroradiology.

RECENT FINDINGS

Magnetic resonance imaging can provide both a detailed anatomic and functional assessment of the pediatric genitourinary tract in a single study without the use of ionizing radiation. Magnetic resonance urography combines static and dynamic evaluation of the urinary tract following contrast administration and has been most often applied to the evaluation of hydronephrosis. In addition to unparalleled anatomic assessment, it allows for the evaluation of glomerular filtration rate, renal transit time, and differential renal function. It also provides unique insights into a wide range of obstructive uropathies and has been demonstrated to be useful in the evaluation of complex genitourinary anomalies. Magnetic resonance voiding cystourethrography has been used to rule out vesicoureteral reflux. Magnetic resonance imaging has also been demonstrated to be superior to nuclear scintigraphy for the diagnosis of pyelonephritis and renal scarring.

SUMMARY

Magnetic resonance imaging has emerged as a powerful tool for the diagnosis of pediatric genitourinary anomalies. It provides functional and anatomic assessment with a single procedure that in most cases is superior to conventional procedures. Magnetic resonance imaging will probably become the modality of choice for the imaging of pediatric genitourinary tract anomalies.

Radiation Dose Associated with Unenhanced CT for Suspected Renal Colic: Impact of Repetitive Studies

OBJECTIVE

The purpose of our study was to assess the dose of ionizing radiation delivered through the use of unenhanced CT for suspected renal colic by determining the incidence of repeated unenhanced CT examinations and the cumulative radiation dose delivered.

MATERIALS AND METHODS

All unenhanced CT examinations for suspected renal colic performed at our institution over a 6-year period were included, and patient age, sex, and multiplicity of examinations were determined. For the adult patient, this protocol prescribes a fixed tube current of 200 mA, 140 kVp, and a nominal slice width of 5 mm. The dose-length product (DLP) was estimated for 15 randomly chosen single-detector CT (SDCT) and MDCT adult flank pain examinations using manufacturer's software. The mean DLPs for SDCT and MDCT were computed and converted to effective doses. Total effective doses were calculated for patients who underwent more than three examinations, and values were compared with established standards.

RESULTS

A total of 5,564 examinations were performed on 4,562 patients. Of these patients, 2,795 (61%) were women (mean age, 45.5 +/- 16.2 [SD] years) and 1,731 (38%) were men (mean age, 44.7 +/- 16.4 years), with 144 patients (3%) of pediatric age. The mean effective doses for a single study were 6.5 mSv for SDCT and 8.5 mSv for MDCT. A subset of 176 patients (4%) had three or more examinations, with estimated effective doses ranging from 19.5 to 153.7 mSv. All patients with multiple examinations had a known history of nephrolithiasis.

CONCLUSION

Patients with a history of nephrolithiasis and flank pain are at increased risk for serial CT with potentially high cumulative effective doses.

Transitional Cell Carcinoma of the Upper Urinary Tract: Spectrum of Imaging Findings

Transitional cell carcinoma (TCC) accounts for up to 10% of neoplasms of the upper urinary tract and usually manifests as hematuria. Imaging plays an important role in assessment of upper tract disease, unlike in bladder TCC, diagnosis of which is usually made at cystoscopy. Traditional imaging modalities, such as excretory urography, retrograde pyelography, and ultrasonography, still play pivotal roles in diagnosis of upper tract TCC, in combination with endourologic techniques. The multicentric nature of TCC makes assessment of the entire urothelium essential before treatment. The advent of minimally invasive surgery, which allows renal preservation in selected patients, makes accurate tumor staging mandatory to determine the appropriate therapy; staging is usually performed with computed tomography (CT) or magnetic resonance (MR) imaging. Vigilant urologic and radiologic follow-up is warranted to assess for metachronous lesions and recurrence. The emerging technique of CT urography allows detection of urinary tract tumors and calculi, assessment of perirenal tissues, and staging of lesions; it may offer the opportunity for one-stop evaluation in the initial assessment of hematuria and in follow-up of TCC. Similar MR imaging protocols can be used in patients who are not candidates for CT urography, although detection of urinary tract calcifications may be suboptimal.

Accuracy of reporting of intravenous urograms: a comparison of radiographers with radiology specialist registrars

AIM

To evaluate whether uroradiographers trained to do so can interpret intravenous urograms as accurately as radiology specialist registrars (SpRs).

METHODS

A total of 150 consecutive IVU examinations were prospectively assessed. The preliminary reporter (a uroradiographer, or an SpR in years 1 to 4) wrote a provisional report on each, and all the IVUs were subsequently assessed by an experienced uroradiologist blinded to the provisional report. The uroradiologist's report was taken as the standard. Comparisons between the provisional reports and the standard were made by Pearson chi-squared test (chi(2)).

RESULTS

Data were available for 149 IVUs. In comparison with the standard report, 1st year SpRs interpreted the IVU series with an accuracy of 76%; the combined group of 2nd, 3rd and 4th year SpRs achieved an accuracy of 88%, whereas the uroradiographers demonstrated an accuracy of 92%. Overall, the difference was to be statistically significant (p=0.021), with a linear trend for increased accuracy with increased experience being highly significant (p=0.006).

CONCLUSION

The uroradiographers significantly outperformed all the SpRs from years 1 to 4, achieving 92% accuracy in interpretation compared with an experienced consultant uroradiologist.

PATIENTS AT HIGH RISK FOR UPPER TRACT UROTHELIAL CANCER: EVALUATION OF HYDRONEPHROSIS USING HIGH RESOLUTION MAGNETIC RESONANCE UROGRAPHY

PURPOSE

We assessed the potential of magnetic resonance urography (MRU) in the evaluation of hydronephrosis not explained by standard investigation in patients at high risk for upper tract urothelial cancer.

MATERIALS AND METHODS

A total of 23 consecutive patients in a specialist urological unit with unexplained hydronephrosis prospectively underwent MRU which comprised overview heavily T2-weighted MR urographic images followed by focused high resolution turbo spin echo T2-weighted sequences obtained in an axial and coronal oblique plane through the level of urinary obstruction. All were at high risk for urothelial cancer and had either contraindications to or problems with standard investigations including poor contrast excretion due to obstruction or renal failure, failed ureteral cannulation or contrast allergy. Clinical events and imaging followup, subsequent endoscopic/surgical findings and histopathology validated MR findings.

RESULTS

In 23 patients with a high clinical suspicion of upper tract transitional cell tumors (TCC), 8 ureteral and 5 renal pelvic TCCs (2 bilateral) were diagnosed by MR, and confirmed histologically. In a further 5 patients benign causes for the hydronephrosis were found. No intrinsic or extrinsic pathology was demonstrable in 5 patients whose imaging findings were stable during 1 year of followup.

CONCLUSIONS

MRU is a valuable noninvasive investigation for evaluating hydronephrosis in this group of patients with suspected urothelial cancer in which routine investigation had failed to provide clinically important information. Focused high resolution T2-weighted images were reliable in the diagnosis of ureteral and renal pelvic TCCs, and were valuable in excluding these and other mass lesions as the cause of hydronephrosis.

Can computed tomography in the protocol for renal colic be interpreted by urologists?

OBJECTIVE

To examine the ability of urologists to independently (with no radiology consultation) interpret non-contrast-enhanced spiral computed tomography (CT) in patients with acute renal colic.

PATIENTS AND METHODS

One hundred consecutive patients presenting to the emergency department with suspected renal colic and evaluated with non-contrast spiral CT were retrospectively reviewed. The CT films of each patient were assessed separately by a first-year urology registrar and by a consultant urologist (neither of whom were subspecialized in uroradiology or endourology). The acute presentation details were provided to mimic the emergency situation.

RESULTS

Ureteric calculi causing acute renal colic were evident in 54 patients. The consultant radiologist reported 51 ureteric calculi, and had a sensitivity, specificity and positive predictive value of 94.5%, 100% and 100%, respectively. The consultant urologist correctly identified 52 calculi, with sensitivity, specificity and positive predictive values of 96.3%, 82.7% and 86.7%. The urology registrar detected 51 stones with sensitivity, specificity and positive predictive values of 94.5%, 93.5% and 94.5%, respectively.

CONCLUSION

Non-contrast spiral CT in patients with acute renal colic is an effective diagnostic tool which allows rapid and accurate evaluation of the urinary tract, thereby facilitating the acute management of patients with renal colic.

Diagnostic value of diuretic-enhanced excretory MR urography in patients with obstructive uropathy

PURPOSE

Ultrasonography and conventional intravenous urography are most common methods in diagnosis of obstructive uropathies. The disadvantage of ultrasonography is inability of visualizing middle and lower one thirds of ureter, while intravenous urography is using radiation, also functionally extra loading effect on kidneys. In this study, the diagnostic value of MR urography on obstructive uropathy were investigated.

MATERIALS AND METHODS

Forty five patients who were suffered from obstructive uropathy examined by ultrasonography, intravenous urography and diuretic-enhanced excretory MR urography by using MR-contrast-agent.

RESULTS

MR urography established accuracy rate of 92.8% for stone diseases which formed the largest group in this study, however, in other causes of obstructive uropathy, MR urography provide 100% correct diagnosis.

CONCLUSION

MR urography provide high quality images for diagnosing and determining causes of urinary obstruction defining position and severity of dilatations as well as showing localization of the pathology. We think that MR urography should be a primary investigation in patients with obstructive uropathy who have contrast agent and X-ray contrindication.

DIAGNOSIS OF URETERAL OBSTRUCTION IN PATIENTS WITH COMPROMISED RENAL FUNCTION: THE ROLE OF NONINVASIVE IMAGING MODALITIES

We compared the role of noncontrast computerized tomography (NCCT), magnetic resonance urography (MRU), and combined abdominal radiography (KUB) and ultrasonography (US) in the diagnosis of the cause of ureteral obstruction in patients with compromised renal function.

MATERIALS AND METHODS

The study included 149 patients, of whom 110 had bilateral obstruction and 39 had obstruction of a solitary kidney. Therefore, the total number of renal units was 259. All patients had renal impairment with serum creatinine greater than 2.5 mg/dl. Besides conventional KUB and US all patients underwent NCCT and MRU. The gold standard for diagnosis of the cause of obstruction included retrograde or antegrade ureterogram, ureteroscopy and/or open surgery. The sensitivity, specificity and overall accuracy of NCCT, MRU, and combined KUB and US in the diagnosis of ureteral obstruction were calculated in comparison with the gold standard.

RESULTS

The definitive cause of ureteral obstruction was calculous in 146 and noncalculous in 113 renal units, including ureteral stricture in 65, bladder or ureter in 43, extraurinary collection in 3 and retroperitoneal fibrosis in 2. The site of stone impaction was identified by NCCT in all 146 renal units (100% sensitivity), by MRU in 101 (69.2% sensitivity), and by combined KUB and US in 115 (78.7% sensitivity) with a difference of significant value in favor of NCCT (p <0.001). Ureteral strictures were identified by NCCT in 18 of the 65 cases (28%) and by MRU in 54 of 65 (83%). Bladder and ureteral tumors causing ureteral obstruction could be diagnosed in approximately half of the patients by NCCT (22 of 43) and in all except 1 by MRU (42 of 43). NCCT and MRU could identify all extraurinary causes of obstruction. Overall of the 113 kidneys with noncalculous obstruction the cause could be identified by MRU in 101 (89% sensitivity), by NCCT in 45 (40% sensitivity), and by combined KUB and US in only 20 (18% sensitivity) with a difference of significant value in favor of MRU (p <0.001).

CONCLUSIONS

In patients with renal impairment due to ureteral obstruction NCCT has superior diagnostic accuracy for detecting calculous causes of obstruction but MRU is superior for identifying noncalculous lesions.

[Imaging of chronic and intermittent adult upper urinary tract obstruction]

State-of-the-art analysis of non invasive diagnostic imaging techniques to demonstrate upper urinary tract obstruction. Advances in imaging techniques are illustrated (sonography, CT scan, MRI). The imaging features of different presentations of chronic and intermittent obstruction are described with reference to current imaging modalities. New strategies for evaluation of chronic and intermittent upper urinary tract obstruction are proposed using ultrasonography as the first line examination. The role of MRI is illustrated. Causes of obstruction are classified based from the intraluminal, parietal or extrinsic location of the lesion.

Diagnosis of noncalcareous hydronephrosis: role of magnetic resonance urography and noncontrast computed tomography

OBJECTIVES

To evaluate the role of magnetic resonance urography (MRU) and noncontrast computed tomography (NCCT) in the diagnosis of noncalcareous hydronephrosis when excretory urography (intravenous urography) is either contraindicated or inconclusive.

METHODS

A total 108 consecutive patients with noncalcareous hydronephrosis were included in this study. In all patients, intravenous urography was either contraindicated or could not determine the diagnosis. In all patients, calculus obstruction was excluded by NCCT and all underwent heavily T2-weighted MRU. The final definitive diagnosis was established by retrograde or antegrade ureterography, endoscopy, or open surgery and was considered the reference standard for the diagnosis of obstruction. Normal kidneys in patients with unilateral obstruction were considered the reference standard for the absence of obstruction. The results of MRU were compared with those of NCCT regarding sensitivity, specificity, and overall accuracy.

RESULTS

Of the 108 patients, 5 had bilateral obstruction and the remaining 103 had unilateral obstruction. Of the latter group, 5 had a solitary kidney; therefore, the total number of renal units was 211 (113 obstructed and 98 normal units). Ureteral strictures were identified by NCCT in 15 (28%) of 54 and by MRU in 45 (83%) of 54 patients. Bladder, ureter, or prostate tumors causing ureteral obstruction could be diagnosed in one half of the 54 patients with such tumors by NCCT (27 of 54) and in all but 2 patients by MRU (52 of 54). Both NCCT and MRU could identify all extraurinary causes of obstruction. Overall, of the 113 kidneys with noncalculus obstruction, the cause could be identified by MRU in 102 (sensitivity of 90%) and by NCCT in 47 (sensitivity of 42%), a difference of statistically significant value in favor of MRU (P <0.001). The specificity of T2-weighted MRU and NCCT was 100% and 99%, respectively (not a statistically significant difference). The overall accuracy of T2-weighted MRU and NCCT was 95% and 68%, respectively (P <0.001).

CONCLUSIONS

In patients with ureteral obstruction in whom intravenous urography is not helpful and after NCCT has excluded stone disease, heavily T2-weighted MRU is a sensitive and specific method in the identification of the cause of obstruction.

Surveillance and management of recurrence for upper tract transitional cell carcinoma

Surveillance of treated upper tract TCC must be tailored to each patient based on individual tumor characteristics. Important risk factors include tumor stage, grade, and multifocality. Molecular markers for TCC may assist in future surveillance strategies, but for now remain experimental. Improvements in imaging eventually may provide the sensitivity needed to determine tumor stage, which would make both initial and recurrence management decisions much more accurate. Initial surgical treatment will influence surveillance when it pertains to superficial disease treated conservatively with either open segmental resection or, now more commonly, with endoscopic resection. Patients treated in this manner require vigilant surveillance of the ipsilateral ureter. Direct visualization in combination with cytology currently appears to be the most effective method, using the same timelines as those used for bladder TCC. Prospective studies concerning surveillance protocols for upper tract TCC would certainly provide more evidence for the current recommendations. However, the evidence does show that upper tract TCC behaves biologically much in the same fashion as does bladder TCC. In light of this fact, the current recommendations are meant to suggest following a patient after treatment for upper tract TCC in a manner similar to that used to follow a patient after treatment of bladder TCC, with individual strategies based on tumor characteristics. For superficial disease, the technology now exists to moniter a patient after endoscopic resection of an upper tract tumor in exactly the same manner used to follow a patient after endoscopic resection of a bladder tumor.

CT urography and MR urography

CT urography and MR urography are an evolving concept and developing technique. As the technology matures, CT urography will combine the ultimate diagnostic capabilities of intravenous urography and CT. In the near future, many intravenous urograms will be replaced by CT urography to evaluate patients with hematuria and other genitourinary conditions. MR urography currently serves as an alternative imaging technique to intravenous urography and CT urography for children and pregnant women and for patients with contraindications to iodinated contrast media.

Evaluation of the patient with flank pain and possible ureteral calculus

Flank pain due to urolithiasis is a common problem in patients presenting to emergency departments. Radiology plays a vital role in the work-up of these patients. Many modalities can be used, including ultrasonography, nuclear medicine, and the traditionally used techniques of intravenous urography and conventional radiography. The development of nonenhanced computed tomography (CT) (single- or multi-detector row helical) has provided a means to enable detection and characterization of urolithiasis with unprecedented sensitivity, specificity, and accuracy while yielding important information for treatment planning, including the size and location of calculi. This technique can also help detect causes for flank pain outside the genitourinary tract. However, close attention must be paid to all aspects of the CT study to prevent misdiagnoses.

Impact of magnetic resonance urography on preoperative diagnostic workup in children affected by hydronephrosis: should IVU be replaced?

PURPOSE

The aim of this study was to determine the role of magnetic resonance urography (MRU) in preoperative diagnostic workup of children with hydronephrosis in a prospective clinical study with comparison of MRU, standard diagnostic investigations, and intraoperative findings.

METHODS

Thirty-one children with hydronephrosis secondary to different causes underwent ultrasound scan (US), intravenous urography (IVU), micturation cysto-urethrography (MCU), isotope nephrography (ING) and MRU. For MRU the authors performed sagittal and coronal halve-Fourier SSFSE scans in a 1.5 Tesla MR system. T1- and T2-weighted sequences were used in axial orientation to improve morphologic information. In 24 patients, preoperative data were compared with intraoperative findings.

RESULTS

Comparison of the different imaging modalities proved MRU to be able to provide more detailed information about the correct localization of stenoses along the urinary tract and the morphology of renal parenchyma. MRU showed the highest concordance of all imaging modalities with intraoperative findings.

CONCLUSION

As a reliable investigation, MRU has the potentials to replace IVU in preoperative diagnostic workup of hydronephrosis in childhood.