Use of magnetic resonance urography

Diagnostic utility of axial imaging in the evaluation of hematuria: A systematic review and critical appraisal of the literature

INTRODUCTION

Increasing severity of hematuria is instinctively associated with higher likelihood of urological malignancy. However, the robustness of the evidentiary base for this assertion is unclear, particularly as it relates to the likelihood of upper urinary tract pathology. Thus, the value of axial imaging in the diagnostic workup of hematuria is unclear due to differences in the underlying patient populations, raising concern for sampling bias. We performed a systematic review to characterize the literature and association between severity of hematuria and likelihood of upper urinary tract cancer based on axial imaging.

METHODS

MEDLINE, EMBASE, and Cochrane were systematically searched for all studies reporting on adult patients presenting with hematuria. We used Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) for reporting of this systematic review and meta-analysis and the Newcastle-Ottawa Scale for risk of bias assessment. Degree of hematuria was classified as "microscopic," "gross," or "unspecified." Three urological malignancies (bladder, upper tract urothelial, and renal cancer) were considered both individually and in aggregate. Random-effects model with pairwise comparisons was employed to arrive at the axial imaging diagnostic yields.

RESULTS

Twenty-nine studies were included, of which six (20.7%) reported on patients with gross hematuria only, four (13.8%) reported on patients with microscopic hematuria only, seven (24.1%) included both, and 12 (41.4%) did not define or specify the severity of hematuria. Of 29 studies, two (6.9%) were at high-risk of bias, 21 (72.4%) at intermediate-risk, and six (20.7%) at low-risk of bias using the Newcastle-Ottawa criteria. Based on axial imaging, rates of diagnoses of renal, upper tract urothelial, and bladder cancers differed with differing severity of hematuria. Notably, rates of renal and upper tract urothelial carcinoma were higher in studies of patients with unspecified hematuria severity (3.6% and 10.4%, respectively) than among patients with gross hematuria (1.5% and 1.3%, respectively). When all urological malignancies were pooled, patients with unspecified hematuria were diagnosed more frequently (19.5%) compared to those with gross (15.3%) and microscopic hematuria (4.5%, difference=1.51%, 99% confidence interval 3.6-26.5%).

CONCLUSIONS

Lack of granularity in the available literature, particularly with regards to patients with unspecified hematuria severity, limits the generalizability of these results and highlights the need for future studies that provide sufficient baseline information, allowing for firmer conclusions to be drawn.

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.

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 Imaging in the Surveillance of Urologic Malignancies

Urologic malignancies are common, accounting for approximately 25% of all new cancer cases in the United States. Patients with urologic malignancies require long-term surveillance to detect progression or recurrence as early as possible. The urologist is faced with the task of balancing patient safety and cost-effectiveness, while finding the most practical follow-up regimen. For each urologic malignancy, this article reviews the commonly used radiologic techniques for surveillance and offers recommended follow-up schedules.

[MR urography: principles, examination techniques, indications]

MR urography is an evolving and promising technique in the evaluation of the urinary tract. MR urography is currently considered the method of choice for imaging of the renal parenchyma and the collecting systems in patients who cannot undergo routine radiographic studies such as pregnant women, pediatric patients, patients allergic to iodinated contrast agents, or patients with impaired renal function. The future development of MR urography in terms of functional, cellular, and molecular imaging is presently the subject of research. The ability of MR imaging to provide quantitative functional information (e.g., on blood flow, perfusion, glomerular filtration rate, and excretion as well as urine drainage) in addition to morphologic assessment of the parenchyma and the collecting system could lead to a single, "all-in-one approach" examination technique.

Virtual Endoscopy: Navigation within Pelvicaliceal System

PURPOSE

To evaluate the use of virtual endoscopy (VE) for the investigation of the pelvicaliceal unit and the depiction of its anatomic deformities.

PATIENTS AND METHODS

Two study groups were prospectively enrolled in our protocol: ten patients with nonurologic pathologies, and thus without any known deformity of the pelvicaliceal unit (group A), and five patients with caliceal obstruction (group B). Virtual endoscopy represented a non-invasive technique providing amplification of the image in three-dimensional space.

RESULTS

Virtual endoscopy was feasible in all patients, and in all cases succeeded in demonstrating the threedimensional morphology of the region of interest. The entire processing time ranged from 10 to 15 minutes (mean 12.6 minutes), and the three-dimensional image could be viewed from different angles, allowing better evaluation of the collecting system and its deformities than is possible with conventional intravenous urography or percutaneous nephrostomography.

CONCLUSION

Virtual endoscopy enabled the creation of endoluminal views of the renal pelvis and calices from spiral tomographic images, thereby allowing diagnostic-preoperative and postoperative evaluation of the pelvicaliceal unit.

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.

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.

Magnetic resonance urography in patients with neurogenic bladder dysfunction and spinal dysraphism

OBJECTIVE

To investigate the reliability of magnetic resonance urography (MRU) using heavily T2-weighted very fast spin-echo sequences in imaging the upper urinary tract in patients with spinal dysraphism and neuropathic bladder dysfunction.

PATIENTS AND METHODS

Patients with neuropathic bladder dysfunction secondary to spinal dysraphism may have gross spinal deformity, which makes assessing the urinary tract extremely difficult by ultrasonography or intravenous urography. The study included 50 patients (median age 33 years, range 19-52) with a median (range) Cobb's angle of 60 (0-240) degrees. No contrast medium was given but all patients received 20 mg of intramuscular frusemide 20-30 min before MRU.

RESULTS

Thirty-five patients had previous ultrasonography, during which only 42 kidneys and no ureters were visible. Of the 94 renal tracts, MRU visualized all kidneys and 86 (89%) ureters. There was good agreement amongst observers on assessing the kidneys and pelvicalyceal systems (kappa > or = 0.61) but only moderate agreement on evaluating the ureters (kappa < or = 0.61). There was disagreement on normality vs renal parenchymal scarring in 14 (15%) kidneys, about no dilatation vs dilatation of the pelvicalyceal system in 14 (15%) systems and about no dilatation vs dilatation of the ureter in 20 (22%) ureters. The overall quality of the MRU images was rated highly, with a mean (range) score of 4.6 (3-5).

CONCLUSION

MRU provides a reliable noninvasive technique for imaging the upper tract in patients who were previously difficult to investigate.

Patients with acute flank pain: comparison of MR urography with unenhanced helical CT

PURPOSE

To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis.

MATERIALS AND METHODS

Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results.

RESULTS

At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004).

CONCLUSION

In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.

MR urography in evaluation of acute flank pain: T2-weighted sequences and gadolinium-enhanced three-dimensional FLASH compared with urography. Fast low-angle shot

OBJECTIVE

The aim of this study was to compare the usefulness of breath-hold heavily T2-weighted sequences with gadolinium-enhanced three-dimensional fast low-angle shot (3D FLASH) MR urography in the evaluation of patients with acute flank pain.

SUBJECTS AND METHODS

Forty consecutive patients with symptoms of acute flank pain underwent MR urography followed immediately by excretory urography. Heavily T2-weighted (combined thin-slice half-Fourier acquisition single-shot turbo spin-echo [HASTE] and thick-slab single-shot turbo spin-echo) and 3D FLASH sequences were evaluated separately and independently by two experienced radiologists for the presence, cause, level, and degree of obstruction. Interobserver agreement was calculated using the kappa statistic. Excretory urography and the final clinical diagnosis were used as reference.

RESULTS

Twenty-six patients were found to have unilateral obstruction caused by ureteral stones. Both MR urography methods were excellent for detecting obstruction. In the detection of stones 3D FLASH was superior, with a sensitivity of 96.2% and 100% and specificity of 100% and 100% for observers A and B, respectively, compared with a sensitivity of 57.7% and 53.8% and a specificity of 100% and 100%, respectively, for T2-weighted sequences. The best degree of obstruction was seen with 3D FLASH, and the interobserver agreement was excellent for stone detection (kappa = 0.97).

CONCLUSION

T2-weighted sequences alone are not sufficient for examining patients with acute flank pain. However, the combined use of both T2-weighted and 3D FLASH sequences will ensure better confidence in the evaluation of acute suspected renal colic. MR urography can replace conventional excretory urography when the latter is contraindicated or undesirable.

MR virtual endoscopy of the upper urinary tract

OBJECTIVE

We investigated the feasibility of applying surface-rendered virtual endoscopy to the visualization of the upper urinary tract by processing unenhanced MR urography data sets.

SUBJECTS AND METHODS

Twenty-six patients, having neoplastic lesions (n = 9), calculi (n = 8), pelviureteric junction stenoses (n = 4), postoperative fibrotic strictures (n = 3), and extrinsic compressions of the ureter (n = 2), underwent unenhanced MR urography. Virtual endoscopy of the upper urinary tract was obtained using a thresholding technique and surface-rendering MR urography data sets.

RESULTS

Virtual endoscopy of the renal pelvis and calices was feasible in all cases on the side of the urinary obstruction. Virtual endoscopy of the ureter was obtained for a diameter of at least larger than 5 mm. The nondilated side could be partially explored in 11 cases (43%). The mean virtual endoscopy threshold required for the visualization of the urinary tract was 157.36-159.94. The mean time for virtual endoscopy was 13.8 min. Endoluminal masses were found in three (12%) of 26 cases on the renal pelvis (corresponding to neoplastic lesions), and occlusions, in 23 (88%) of 26 on the pelviureteric junction and ureter (neoplastic lesions and other abnormalities).

CONCLUSION

Virtual endoscopy of MR urography data sets is feasible in patients with urinary tract dilatation. Virtual endoscopy displays the renal pelvis, calices, and ureter and, moreover, can show endoluminal changes caused by abnormalities.

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

OBJECTIVE

To compare the ability of magnetic resonance urography (MRU), enhanced using gadolinium and frusemide diuresis, and conventional intravenous urography (IVU) to diagnose the cause of ureteric obstruction.

PATIENTS AND METHODS

The study included 82 patients in whom IVU showed or suggested obstruction and who also underwent MRU. The images from both methods were interpreted by various investigators independently; two evaluated the IVU and two others the MRU, the latter being unaware of the diagnosis after IVU. If the diagnosis remained unclear, further investigations (e.g. computed tomography, retrograde pyelography or ureteroscopy) were conducted.

RESULTS

The diagnoses were ureteric calculi in 72 patients, ureteric tumours in eight and extra-ureteric tumours in two. In those with urolithiasis, the diagnosis was correct with IVU in 49 patients and with MRU in 64. The diagnosis in this group was incorrect with MRU in only two patients. The main reason for the failure of IVU was absent contrast medium excretion. Three of eight patients with ureteric tumours were correctly diagnosed by IVU but in three patients the diagnosis was incorrect. MRU correctly diagnosed seven of the eight patients in this group, with no false diagnosis.

CONCLUSION

IVU is currently likely to remain the standard procedure for imaging the upper urinary tract, but this study shows the potential of MRU when enhanced with gadolinium and frusemide. MRU may be helpful if there is a dilated system with no excretory function, in pregnant women, in children and in those with contrast medium allergy.

Ureteroscopic approach to upper-tract urothelial tumors

Transitional-cell carcinoma (TCC) of the upper urinary tract has traditionally been managed by nephroureterectomy, whereas nephron-sparing surgery has been reserved for those few patients with solitary kidneys or bilateral lesions. However, with the introduction of improved diagnostic and therapeutic technology, including smaller ureteroscopes and working instruments, and the concomitant ease of surveillance, ureteroscopic treatment of upper-tract urothelial tumors has become a reasonable alternative to open operative intervention in patients requiring conservative management. Furthermore, as preoperative grading and staging have improved, ureteroscopic treatment of upper-tract urothelial tumors is assuming an increasingly important role in the management of some patients who might have otherwise been treated with a nephroureterectomy. The technique of ureteroscopic resection is described in detail.