Is the excretory phase necessary to identify upper tract urothelial neoplasms at CT urography? A 10-year population-based study

PURPOSE

To assess the proportion of upper tract urothelial carcinomas (UTUC) that are evident without the excretory phase at CT urography (CTU), and the proportion of potentially avoidable radiation.

METHODS

UTUCs diagnosed between January 2008-December 2017 were retrospectively identified from a population-based cancer registry. For each patient, US, non-urographic CT, and MRI exams were assessed for a primary mass and secondary imaging findings (hydronephrosis, urinary tract thickening, luminal distention, fat stranding, and lymphadenopathy/metastatic disease). CTUs were assessed for primary and secondary findings, and whether the tumor was evident as a filling defect on excretory phase. The dose-length product (DLP) of potentially avoidable excretory phases was calculated as a fraction of total DLP.

RESULTS

288 patients (mean age, 72±11 years, 165 males) and 545 imaging examinations were included. Of 192 patients imaged with 370 non-urographic CTs, a primary mass was evident in 154 (80.2%), secondary findings were evident in 172 (89.6%), and primary or secondary findings were evident in 179 (93.2%). Of 175 CTUs, primary and secondary findings were evident in 157 (89.7%) and 166 (94.9%) examinations, respectively, and primary or secondary findings were evident in 170/175 (97.1%). 131/175 (74.9%) UTUCs were evident as a filling defect, including the 5/175 (2.9%) UTUCs without primary or secondary findings. Of 144 CTUs with available DLP data, the proportion of potentially avoidable radiation was 103.7/235.8 (44.0%) Gy⋅cm.

CONCLUSION

In our population, almost all UTUCs were evident via primary or secondary imaging findings without requiring the excretory phase. These results support streamlining protocols and pathways.

Quantitative differentiation of non-invasive bladder urothelial carcinoma and inverted papilloma based on CT urography

PURPOSE

To investigate the value of CT urography (CTU) indicators in the quantitative differential diagnosis of bladder urothelial carcinoma (BUC) and inverted papilloma of the bladder (IPB).

MATERIAL AND METHODS

The clinical and preoperative CTU imaging data of continuous 103 patients with histologically confirmed BUC or IPB were retrospectively analyzed. The imaging data included 6 qualitative indicators and 7 quantitative measures. The recorded clinical information and imaging features were subjected to univariate and multivariate logistic regression analysis to find independent risk factors for BUC, and a combined multi-indicator prediction model was constructed, and the prediction model was visualized using nomogram. ROC curve analysis was used to calculate and compare the predictive efficacy of independent risk factors and nomogram.

RESULTS

Junction smoothness, maximum longitudinal diameter, tumor-wall interface and arterial reinforcement rate were independent risk factors for distinguishing BUC from IPB. The AUC of the combined model was 0.934 (sensitivity = 0.808, specificity = 0.920, accuracy = 0.835), and its diagnostic efficiency was higher than that of junction smoothness (AUC=0.667, sensitivity = 0.654, specificity = 0.680, accuracy = 0.660), maximum longitudinal diameter (AUC=0.757, sensitivity = 0.833, specificity = 0.604, accuracy = 0.786), tumor-wall interface (AUC=0.888, sensitivity = 0.755, specificity = 0.808, accuracy = 0.816) and Arterial reinforcement rate (AUC=0.786, sensitivity = 0.936, specificity = 0.640, accuracy = 0.864).

CONCLUSION

Above qualitative and quantitative indicators based on CTU and the combination of them may be helpful to the differential diagnosis of BUC and IPB, thus better assisting in clinical decision-making.

KEY POINTS

1. Bladder urothelial carcinoma (BUC) and inverted papilloma of the bladder (IPB) exhibit similar clinical symptoms and imaging presentations. 2. The diagnostic value of CT urography (CTU) in distinguishing between BUC and IPB has not been documented. 3. BUC and IPB differ in lesion size, growth pattern and blood supply. 4. The diagnostic efficiency is optimized by integrating multiple independent risk factors into the prediction model.

Unraveling recurrent urinary tract infection in adulthood: a rare case report of unilateral partial duplex collecting system with ureterocele

Introduction

Duplication of the renal collecting system, known as the duplex collecting system, is a common congenital anomaly of the urinary tract. It can be partial or complete and affects 0.7-4% of the population, with a higher incidence in females. Ureteroceles are cystic dilations of the distal ureter and are often asymptomatic, particularly in adults.

Case presentation

The authors present a case of a newly diagnosed partial duplex collecting system of the left kidney and left intravesical ureterocele, which was diagnosed for the first time at the age of 47 years, along with a history of symptoms suggestive of recurrent urinary tract infection and a urethral calculus which was surgically managed 5 years ago.

Clinical discussion

The presence of a duplex collecting system can be observed even in males, with the possibility of recurrent urinary tract infection and the rare occurrence of an intravesical ureterocele. While ureteroceles are typically considered a congenital condition, they can also be diagnosed in adults.

Conclusion

A partial duplex collecting system of the left kidney with left intravesical ureterocele in the age of 47 years in a male is a rare occurrence. Diagnosis and management of such urological cases can be challenging especially in a resource limited setting, which can be mitigated by awareness of unusual presentations, proper antenatal care, and access to proper diagnostic tools.

Diagnostic evaluation of upper tract urothelial carcinoma: can we safely omit diagnostic ureteroscopy?

OBJECTIVE

To identify clinicopathological or radiological factors that may predict a diagnosis of upper urinary tract urothelial cell carcinoma (UTUC) to inform which patients can proceed directly to radical nephroureterectomy (RNU) without the delay for diagnostic ureteroscopy (URS).

PATIENTS AND METHODS

All consecutive patients investigated for suspected UTUC in a high-volume UK centre between 2011 and 2017 were identified through retrospective analysis of surgical logbooks and a prospectively maintained pathology database. Details on clinical presentation, radiological findings, and URS/RNU histopathology results were evaluated. Multivariate regression analysis was performed to evaluate predictors of a final diagnosis of UTUC.

RESULTS

In all, 260 patients were investigated, of whom 230 (89.2%) underwent URS. RNU was performed in 131 patients (50.4%), of whom 25 (9.6%) proceeded directly without URS - all of whom had a final histopathological diagnosis of UTUC - and 15 (11.5%) underwent RNU after URS despite no conclusive histopathological confirmation of UTUC. Major surgery was avoided in 77 patients (33.5%) where a benign or alternative diagnosis was made on URS, and 14 patients (6.1%) underwent nephron-sparing surgery. Overall, 178 patients (68.5%) had a final diagnosis of UTUC confirmed on URS/RNU histopathology. On multivariate logistic regression analysis, a presenting complaint of visible haematuria (hazard ratio [HR] 5.17, confidence interval [CI] 1.91-14.0; P = 0.001), a solid lesion reported on imaging (HR 37.8, CI = 11.7-122.1; P < 0.001) and a history of smoking (HR 3.07, CI 1.35-6.97; P = 0.007), were predictive of a final diagnosis of UTUC. From this cohort, 51 (96.2%) of 53 smokers who presented with visible haematuria and who had a solid lesion on computed tomography urogram had UTUC on final histopathology.

CONCLUSION

We identified specific factors which may assist clinicians in selecting which patients may reliably proceed to RNU without the delay of diagnostic URS. These findings may inform a prospective multicentre analysis including additional variables such as urinary cytology.

Computed Tomography Urography: State of the Art and Beyond

Computed Tomography Urography (CTU) is a multiphase CT examination optimized for imaging kidneys, ureters, and bladder, complemented by post-contrast excretory phase imaging. Different protocols are available for contrast administration and image acquisition and timing, with different strengths and limits, mainly related to kidney enhancement, ureters distension and opacification, and radiation exposure. The availability of new reconstruction algorithms, such as iterative and deep-learning-based reconstruction has dramatically improved the image quality and reducing radiation exposure at the same time. Dual-Energy Computed Tomography also has an important role in this type of examination, with the possibility of renal stone characterization, the availability of synthetic unenhanced phases to reduce radiation dose, and the availability of iodine maps for a better interpretation of renal masses. We also describe the new artificial intelligence applications for CTU, focusing on radiomics to predict tumor grading and patients' outcome for a personalized therapeutic approach. In this narrative review, we provide a comprehensive overview of CTU from the traditional to the newest acquisition techniques and reconstruction algorithms, and the possibility of advanced imaging interpretation to provide an up-to-date guide for radiologists who want to better comprehend this technique.

Use of dual energy CT urography in evaluation of urinary stone and complex cyst

BACKGROUND

Dual-energy computed tomography scans can provide significant benefits to the urinary system. The aim of this study is to determine the limitations and benefits of using dual energy CT urography in patients with urinary system stones and cysts.

METHODS

In the analysis of the images, the virtual noncontrasted images obtained from the combined nephrogenicexcretory phase and the true noncontrasted images were evaluated. The true noncontrast images were accepted as the gold standard for stone detection.

RESULTS

Eighty-three different stones were detected in 26 of the 115 patients included in the study. Sensibilities of virtual noncontrast images in detecting urinary system stones were 66.7% and 65.4% according to the first and second radiologists, respectively. In this study, 32 hyperdense cysts were detected. According to iodine map images, there was no enhancement in 26 of 32 cysts; only 5 cysts showed minimal contrast enhancement. One patient could not decide on contrast enhancement.

DISCUSSION

As a result, if CT urography is performed with dual energy, it can provide additional information in patients with urinary system disorder.

Optimizing Upper-Tract Imaging for Non-Visible Haematuria

INTRODUCTION

Non-visible haematuria (NVH) is associated with a small risk of upper-tract urothelial carcinoma (UTUC), though there is little consensus on its investigation, particularly with regard to upper-tract imaging. This study aimed to determine whether the presentation of UTUC can guide investigation of NVH in patients under 60 years old.

METHODS

All patients investigated at our one-stop haematuria clinics under a cancer pathway were reviewed during a 5-year period, with all patients undergoing cystoscopy and upper-tract imaging. Retrospective analysis of all UTUC cases from our urological cancer multidisciplinary team meeting database over a 10-year period was also undertaken.

RESULTS

2,129 patients with a median age of 67 years underwent urgent investigation for haematuria between March 2015 and February 2020. 449 cases presented with NVH, of whom 124 (27.6%) were under 60. Out of 21 cases of UTUC, only 2 presented with NVH; both were over the age of 60 years. Factors that independently predicted diagnosis with urinary-tract malignancy were age ≥60 (OR 3.70, p < 0.001), visible haematuria (OR 2.50, p = 0.006), and suspicious cystoscopic findings (OR 58.06, p < 0.001). Review of all 119 UTUC cases over 10 years found 6 cases (5.0%) presenting with NVH, with one (0.8%) also presenting under 60 years.

CONCLUSION

Diagnosis with UTUC is rare in patients presenting with NVH under the age of 60 years. Routine use of CTU in this low-risk group is best avoided, with ultrasonography constituting a safer first-line upper-tract imaging modality. Guidelines that risk-stratify NVH patients may be effective in reducing unnecessary investigations.

Ureteral fibroepithelial polyp: A case report

Ureteral fibroepithelial polyps are rare, accounting for approximately 2–6% of all ureteral tumors. They can be diagnosed by ultrasonography, computed tomography, and retrograde pyelography; however, diagnosis can be difficult. Management is by resection of the polyp, and endoscopic resection is the standard treatment. Partial ureteral resection and ureteral reconstruction may be necessary depending on the size and location of the polyp. Imaging follow-ups for approximately a year post-surgery are recommended. This clinical case report aimed to highlight a case of a fibroepithelial ureteral polyp that was managed by endoscopic resection.

Imaging of ureter: a primer for the emergency radiologist

In this review article, we will discuss the gamut of abnormalities involving the ureters. In the emergency department, ureterolithiasis is the most common indication for imaging abdomen and pelvis. However, spectrum of ureteral abnormalities including congenital, infectious and inflammatory, primary and secondary ureteral malignancies, retroperitoneal fibrosis rare described in this article may be encountered. Thus, we will describe acute subacute as well as chronic conditions that may affect ureter. Knowledge of common, as well as rare entities and their imaging features, is of utmost importance to enable appropriate management.

Benign ureteral polyps causing upper urinary tract obstruction

Ureteral fibroepithelial polyps are benign, mesodermal neoplasms that can cause upper urinary tract obstruction. The preoperative diagnosis of this disease is challenging, but multidetector computed tomography (CT), particularly CT urography in the excretory phase, can be used to detect the features of ureteral polyps. We illustrated a case preoperatively diagnosed as upper ureteral tract obstruction due to ureteral tumor based on clinical presentation and CT imaging. However, the histopathological report revealed ureteral fibroepithelial polyps. Ureteral fibroepithelial polyps should be considered as a rare cause of urinary obstruction when the clinical presentation and imaging findings are atypical for more common etiologies.

CT Urography Findings of Upper Urinary Tract Carcinoma and Its Mimickers: A Pictorial Review

Urothelial carcinoma (UC) is the fourth most frequent tumor in Western countries and upper tract urothelial carcinoma (UTUC), affecting pyelocaliceal cavities and ureter, accounts for 5-10% of all UCs. Computed tomography urography (CTU) is now considered the imaging modality of choice for diagnosis and staging of UTUC, guiding disease management. Although its specificity is very high, both benign and malignant diseases could mimic UTUCs and therefore have to be well-known to avoid misdiagnosis. We describe CTU findings of upper urinary tract carcinoma, features that influence disease management, and possible differential diagnosis.

Ultra-high-resolution CT urography: Importance of matrix size and reconstruction technique on image quality

PURPOSE

To evaluate the image quality of CT urography (CTU) obtained with ultra-high-resolution CT (U-HRCT) reconstructed with hybrid iterative reconstruction (IR) and model-based IR algorithms.

METHOD

Forty-eight patients who underwent CTU using the U-HRCT system were enrolled in this retrospective study. Excretory phase images were reconstructed with three protocols: Protocol A: 1024-matrix, 0.25 mm-thickness, and model-based IR; Protocol B: 1024-matrix, 0.25 mm-thickness, and hybrid IR; Protocol C: 512-matrix, 0.5 mm-thickness, and model-based IR. Objective image noise and contrast-to-noise ratio (CNR) of the renal pelvis were compared among the protocols. Three-dimensional maximum intensity projection CTU images were generated from each image data set, and image quality was evaluated by two radiologists.

RESULTS

Protocol C yielded the lowest objective image noise and highest CNR, whereas Protocol A had highest image noise and lowest CNR (P <  0.01). Regarding the detailed delineation of urinary tract structures on the images, the mean visual score was significantly higher for Protocol A than for Protocols B and C (P <  0.001), and the mean score for subjective image noise was significantly lower for Protocol A than for Protocols B and C (P <  0.001).

CONCLUSIONS

CTU with a 1024-matrix and model-based IR depicted the structures of the urinary system in the most detail.

Utilization and Yield of CT Urography: Are the American Urological Association Guidelines for Imaging of Patients With Asymptomatic Microscopic Hematuria Being Followed?

OBJECTIVE

The purposes of this study were to determine whether patients with asymptomatic microscopic hematuria undergoing CT urography (CTU) meet the American Urological Association criteria for radiologic evaluation and to determine the yield of CTU for upper tract malignancy.

MATERIALS AND METHODS

A retrospective review was conducted of consecutive CTU examinations performed for asymptomatic microscopic hematuria in adult patients. Patients with clinical evidence suggestive of a benign cause of hematuria (stone, urinary tract infection, trauma) or prior urologic malignancy were excluded. The study group included 419 patients (173 men, 246 women). CT reports were reviewed to identify causes of hematuria in all cases. Evaluate for appropriateness was conducted with 200 randomly allocated patients. Urinalysis results were reviewed, and appropriate use of CTU was defined as more than 3 RBCs per high-power field in the absence of urinary tract infection. Cystoscopy results after CTU were noted.

RESULTS

In total, 58 of 200 patients (29.0%; 95% CI, 23.2-35.6%) did not meet American Urological Association criteria for radiologic evaluation. Fifteen (7.5%) received dipstick analysis only. Thirty-eight (19.0%) had urinalysis results showing 0-2 RBCs per high-power field. Five patients (2.5%) were found to have urinary tract infections. No upper tract urothelial neoplasms were identified (0/419; 95% CI, 0.0-0.9%). One solid renal mass was identified without pathologic confirmation. One possible bladder mass was seen at CTU but not visualized at subsequent cystoscopy.

CONCLUSION

In 29.0% of examinations, CTU is performed for patients who do not meet the criteria for radiologic evaluation. The yield of CTU for upper urinary tract malignancy is low.

Comparison of quality of urinary bladder filling in CT urography with different doses of furosemide in the work-up of patients with macroscopic hematuria

INTRODUCTION

The protocol for preparation of computed tomography urography (CTU) examinations at our hospital was changed in 2013 to improve the quality of urinary bladder filling in the excretory phase. The aim of this study was to evaluate the quality of urinary bladder filling on CTU after different doses of furosemide were administered to patients with macroscopic hematuria.

METHODS

The cohort was 215 patients who underwent elective CTU due to macroscopic hematuria between 2014 and 2018. 5 mg furosemide were administrated to 100 patients, 2.5 mg to 100 patients and 0 mg to 15 patients. Contrast medium layered bladders were excluded, leaving 193 patients: 92, 89 and 12 in each group. Urinary bladder volume was calculated in corticomedullary (CMP) and excretory phase (EP). Bladder distension was classified as satisfactory or not. Attenuation of bladder content in EP was noted.

RESULTS

Average volume in EP was 370 ± 224 ml (28-1052) after 5 mg furosemide, 274 ± 120 ml (43-628) after 2.5 mg and 180 ± 104 ml (53-351) after 0 mg. 85% of the bladders were satisfactory distended after 5 mg, 80% after 2.5 mg and 58% after 0 mg. Average attenuation was 266 ± 89 HU (103-524) after 5 mg, 362 ± 156 HU (118-948) after 2.5 mg and 761 ± 331 HU (347-1206) after 0 mg. The differences in volume and attenuation were significant.

CONCLUSION

5 mg furosemide is preferred rather than 2.5 mg in preparation for CTU examinations of patients with macroscopic hematuria. There was no difference between the doses concerning rate of satisfactory bladder distension, but the higher dose resulted in larger bladder volume and more suitable attenuation of bladder content.

IMPLICATIONS FOR PRACTICE

Development of CTU-image quality could improve bladder cancer diagnostics.

The Diagnostic Yield of CT Urography in the Workup of Hematuria With Negative Cystoscopy [Formula: see text]

PURPOSE

To determine the diagnostic yield of computed tomography urography (CTU) in patients evaluated for hematuria with negative cystoscopy and to assess the added value of CTU when compared with ultrasound (US) in this patient population.

METHODS

A retrospective study was conducted of patients who underwent CTU within 12 months of negative cystoscopy for workup of hematuria at our institution from January 2016 to December 2017. Computed tomography urography findings were recorded and compared to clinical diagnoses to determine diagnostic yield. Computed tomography urography and US findings were compared in patients who underwent both examinations. Patient characteristics (age, sex, smoking history, and hematuria subtype) were reported.

RESULTS

A total of 657 patients met the inclusion criteria, including 108 patients aged 50 years and younger. No cause for hematuria was identified in 41% of patients overall and 58% of patients aged 50 years and younger. The most common diagnoses were benign prostatic hyperplasia and urolithiasis, accounting for 25% and 21% of patients, respectively; 0.6% of patients were diagnosed with an upper urinary tract malignancy, all older than 50 years. Although US was superior or equal to CTU for diagnosis in 83% of patients who underwent both examinations, US had a 0% sensitivity for detection of upper urinary tract malignancy.

CONCLUSION

The low diagnostic yield of CTU and low prevalence of upper urinary tract malignancy in patients evaluated for hematuria with negative cystoscopy, particularly those aged 50 years and younger, call into question the appropriateness of multiphasic CTU as a first-line imaging modality in this population.

The utility of retrograde pyelography to follow up incompletely opacified ureters on CT urography

PURPOSE

Retrograde pyelography (RPG) is used in some centers to further evaluate patients with incompletely opacified segments on CT urography (CTU). This study intends to evaluate the utility of this imaging combination in terms of the yield of abnormal findings on the follow up RPG.

METHODS

In this retrospective study, we searched the radiology database over a three-year period (11/1/2015-10/30/2018) for patients who had a CTU and then a diagnostic RPG within 180 days. Images and reports were reviewed from this period for patients who met the inclusion criteria.

RESULTS

292 patients underwent a CTU with follow up RPG over the search period. 131/292 RPGs (44.9%) were performed because the CTU described at least one incompletely opacified ureteral segment. Of the 148 ureters evaluated in these 131 patients, 4 ureters (2.7%) showed an abnormality on follow up retrograde pyelogram-two revealed a stricture at the unfilled segment, and two revealed contour irregularity in the distal ureter (biopsy showed urothelial cell carcinoma in these two).

CONCLUSION

There is a relatively low yield for detecting ureteral abnormalities when a retrograde pyelogram is performed after a CTU to evaluate an incompletely opacified ureteral segment-2.7% in our study, with only two of these incompletely opacified segments containing urothelial cancer (1.4%). In these two cases, a ureteral abnormality was visible on the CTU and RPG would seem to have a very low yield for follow up of unopacified ureteral segments if the ureters are otherwise normal-appearing on CTU and there is no hydronephrosis.

Prevalence of Urologic Disease Among Patients Investigated for Hematuria With CT Urography

PURPOSE

The current study evaluated the prevalence of urologic disease among patients with hematuria referred for computerized tomography (CT) urography to determine which patients require investigation with CT urography.

METHODS

We retrospectively reviewed radiology reports of 1046 CT urograms performed for the indication of microscopic (43.7%) or gross hematuria (56.3%). Urological findings were categorized as negative, benign, or suspicious (pathologically confirmed) for malignancy.

RESULTS

Of 1046 CT urograms performed, 53.5% were negative, 36.4% were benign, and 10% were suspicious for malignancy. The most common benign finding was urolithiasis (22.3%). Overall, urinary tract malignancies were present in 3.6% of patients, and the rate was significantly higher (P < .001) for gross (5.8%) than microscopic hematuria (0.9%). CT urography identified 0.6% patients with upper urinary tract malignancies; the malignancy rate was significantly higher (P = .038) for gross (1%) than microscopic hematuria (0%), and no significant sex (P = 1.00; male = 0.6%, female = 0.6%) or age (P = .600; < 50 years = 0%, ≥ 50 years = 0.7%) differences were observed. Logistic regression revealed that being male was associated with gross hematuria (odds ratio [OR] = 2.92), and that both age and gross hematuria (ORs = 1.06 and 5.13, respectively) were associated with malignancy.

CONCLUSIONS

CT urography found no upper urinary tract malignancies in 99.4% of patients presenting with hematuria, including all patients with microscopic hematuria and those with gross hematuria <50 years old. Investigating these subgroups with CT urography may be unnecessary and result in increased patient morbidity and health-care costs.

What a difference a delay makes! CT urogram: a pictorial essay

PURPOSE

The aim of this pictorial essay is to demonstrate several cases where the diagnosis would have been difficult or impossible without the excretory phase image of CT urography.

METHODS

A brief discussion of CT urography technique and dose reduction is followed by several cases illustrating the utility of CT urography.

RESULTS

CT urography has become the primary imaging modality for evaluation of hematuria, as well as in the staging and surveillance of urinary tract malignancies. CT urography includes a non-contrast phase and contrast-enhanced nephrographic and excretory (delayed) phases. While the three phases add to the diagnostic ability of CT urography, it also adds potential patient radiation dose. Several techniques including automatic exposure control, iterative reconstruction algorithms, higher noise tolerance, and split-bolus have been successfully used to mitigate dose. The excretory phase is timed such that the excreted contrast opacifies the urinary collecting system and allows for greater detection of filling defects or other abnormalities. Sixteen cases illustrating the utility of excretory phase imaging are reviewed.

CONCLUSIONS

Excretory phase imaging of CT urography can be an essential tool for detecting and appropriately characterizing urinary tract malignancies, renal papillary and medullary abnormalities, CT radiolucent stones, congenital abnormalities, certain chronic inflammatory conditions, and perinephric collections.

CT urography: how to optimize the technique

PURPOSE

Computed tomography urography (CTU) has emerged as the modality of choice for imaging the urinary tract within the past few decades. It is a powerful tool that enables detailed anatomic evaluation of the urinary tract in order to identify primary urothelial malignancies, benign urinary tract conditions, and associated abdominopelvic pathologies. As such, there have been extensive efforts to optimize CTU protocol.

METHODS

This article reviews the published literature on CTU protocol optimization, including contrast bolus timing, dose reduction, reconstruction algorithms, and ancillary practices.

CONCLUSION

There have been many advances in CTU techniques, which allow for imaging diagnosis of a wide spectrum of diseases while minimizing radiation dose and maximizing urinary tract distension and opacification.

Application of Iterative Metal Artifact Reduction Algorithm to CT Urography for Patients With Hip Prostheses

OBJECTIVE. The purpose of this study is to retrospectively assess the impact of iterative metal artifact reduction (IMAR) with iterative reconstruction (IR) on the image quality and diagnostic performance of CT urography in the evaluation of patients with hip prostheses, compared with IR alone. MATERIALS AND METHODS. CT urography examinations that were reconstructed using IR with and without IMAR were analyzed for 57 patients (29 women and 28 men; mean age, 74 years [range, 22-94 years]) with hip prostheses (40 unilateral and 17 bilateral). For quantitative analysis, image noise within the bladder was measured. Two radiologists (radiologist 1 [RAD1] and radiologist 2 [RAD2]) qualitatively evaluated the images using both a 5-point scale to assess the degree of visualization of artifacts and a 6-point scale to determine diagnostic confidence in visualization of the bladder, ureters, prostate or uterus, pelvic calcifications, and genitourinary abnormalities involving the bladder, distal ureters, prostate, uterus, and ovaries. RESULTS. The combination of IMAR and an IR technique provided improvement in quantitative and qualitative measurements (p < 0.05). Forty-three genitourinary abnormalities were detected in 29 patients. Quantitative and qualitative comparisons of scans obtained with and without the use of IMAR, respectively, revealed image noise of 99.6 versus 173.3 HU and the following radiologist scores: for improvement of artifacts, 3.2 versus 1.6 (for RAD1) and 3.1 versus 1.6 (for RAD2); for visualization of the bladder, 3.6 versus 1.5 (RAD1) and 3.8 versus 1.6 (RAD2); visualization of the ureters, 3.8 versus 1.6 (RAD1) and 3.9 versus 1.7 (RAD2); visualization of the uterus, 4.3 versus 2.8 (RAD1) and 4.3 versus 2.6 (RAD2); visualization of the prostate, 4.5 versus 2.3 (RAD1) and 4.5 versus 2.2 (RAD2); diagnostic confidence for calcifications, 4.7 versus 3.5 (RAD1) and 4.7 versus 3.3 (RAD2); and diagnostic confidence for genitourinary abnormalities, 5.0 versus 3.2 (RAD1) and 4.8 versus 2.9 (RAD2), respectively. CONCLUSION. The addition of IMAR to IR led to statistically significant improvement in the retrospective diagnostic performance and image quality of CT urography for patients with hip prostheses, compared with IR alone.

Hematuria

Hematuria is common in the primary care setting. It is classified as either gross or microscopic. Hematuria warrants a thorough history and physical to determine potential causes and assess risk factors for malignancy. Risk of malignancy with gross hematuria is greater than 10%, and prompt urologic referral is recommended. Microscopic hematuria most commonly has benign causes, such as urinary tract infection, benign prostatic hyperplasia, and urinary calculi. If no benign cause for microscopic hematuria is found, the work-up includes laboratory tests to rule out intrinsic renal disease, imaging of the urinary tract, and referral to nephrology and urology subspecialists.

Consultation on UTUC, Stockholm 2018 aspects of diagnosis of upper tract urothelial carcinoma

Purpose

To summarize knowledge on upper urinary tract carcinoma (UTUC) regarding diagnostic procedures, risk factors and prognostic markers.

Methods

A scoping review approach was applied to search literature in Pubmed, Web of Science, and Embase. Consensus was reached through discussions at Consultation on UTUC in Stockholm, September 2018.

Results

Tumor stage and grade are the most important prognostic factors. CT urography (CTU) including corticomedullary phase is the preferred imaging modality. A clear tumor on CTU in combination with high-grade UTUC in urine cytology identifies high-risk UTUC, and in some cases indirect staging can be obtained. Bladder urine cytology has limited sensitivity, and in most cases ureterorenoscopy (URS) with in situ samples for cytology and histopathology are mandatory for exact diagnosis. Image-enhancing techniques, Image S1 and narrow-band imaging, may improve tumor detection at URS. Direct confocal laser endomicroscopy may help to define grade during URS. There is strong correlation between stage and grade, accordingly correct grading is crucial. The correlation is more pronounced using the 1999 WHO than the 2004 classification: however, the 1999 system risks greater interobserver variability. Using both systems is advisable. A number of tissue-based molecular markers have been studied. None has proven ready for use in clinical practice.

Conclusions

Correct grading and staging of UTUC are mandatory for adequate treatment decisions. Optimal diagnostic workup should include CTU with corticomedullary phase, URS with in situ cytology and biopsies. Both WHO classification systems (1999 and 2004) should be used to decrease risk of undergrading or overtreatment.

Tumors of Renal Collecting Systems, Renal Pelvis, and Ureters: Role of MR Imaging and MR Urography Versus Computed Tomography Urography

Hematuria evaluation remains a common problem, particularly in patients who smoke and are at risk for urothelial tumors. Lifetime surveillance of the urothelium is often required once urothelial cancer is diagnosed. Computed tomography urography (CTU) has exquisite sensitivity and specificity for identification of renal and urothelial lesions. The examination is well accepted by patients and physicians. Possible harms include radiation exposure and contrast-induced nephropathy. MR imaging is also an accurate test, but requires longer exam times, and may not demonstrate stones. We present the technical and interpretation skills required to use MR urography and CTU effectively.

U-Net based deep learning bladder segmentation in CT urography

OBJECTIVES

To develop a U-Net-based deep learning approach (U-DL) for bladder segmentation in computed tomography urography (CTU) as a part of a computer-assisted bladder cancer detection and treatment response assessment pipeline.

MATERIALS AND METHODS

A dataset of 173 cases including 81 cases in the training/validation set (42 masses, 21 with wall thickening, 18 normal bladders), and 92 cases in the test set (43 masses, 36 with wall thickening, 13 normal bladders) were used with Institutional Review Board approval. An experienced radiologist provided three-dimensional (3D) hand outlines for all cases as the reference standard. We previously developed a bladder segmentation method that used a deep learning convolution neural network and level sets (DCNN-LS) within a user-input bounding box. However, some cases with poor image quality or with advanced bladder cancer spreading into the neighboring organs caused inaccurate segmentation. We have newly developed an automated U-DL method to estimate a likelihood map of the bladder in CTU. The U-DL did not require a user-input box and the level sets for postprocessing. To identify the best model for this task, we compared the following models: (a) two-dimensional (2D) U-DL and 3D U-DL using 2D CT slices and 3D CT volumes, respectively, as input, (b) U-DLs using CT images of different resolutions as input, and (c) U-DLs with and without automated cropping of the bladder as an image preprocessing step. The segmentation accuracy relative to the reference standard was quantified by six measures: average volume intersection ratio (AVI), average percent volume error (AVE), average absolute volume error (AAVE), average minimum distance (AMD), average Hausdorff distance (AHD), and the average Jaccard index (AJI). As a baseline, the results from our previous DCNN-LS method were used.

RESULTS

In the test set, the best 2D U-DL model achieved AVI, AVE, AAVE, AMD, AHD, and AJI values of 93.4 ± 9.5%, -4.2 ± 14.2%, 9.2 ± 11.5%, 2.7 ± 2.5 mm, 9.7 ± 7.6 mm, 85.0 ± 11.3%, respectively, while the corresponding measures by the best 3D U-DL were 90.6 ± 11.9%, -2.3 ± 21.7%, 11.5 ± 18.5%, 3.1 ± 3.2 mm, 11.4 ± 10.0 mm, and 82.6 ± 14.2%, respectively. For comparison, the corresponding values obtained with the baseline method were 81.9 ± 12.1%, 10.2 ± 16.2%, 14.0 ± 13.0%, 3.6 ± 2.0 mm, 12.8 ± 6.1 mm, and 76.2 ± 11.8%, respectively, for the same test set. The improvement for all measures between the best U-DL and the DCNN-LS were statistically significant (P < 0.001).

CONCLUSION

Compared to a previous DCNN-LS method, which depended on a user-input bounding box, the U-DL provided more accurate bladder segmentation and was more automated than the previous approach.

Deep-learning convolutional neural network: Inner and outer bladder wall segmentation in CT urography

PURPOSE

We are developing a computerized segmentation tool for the inner and outer bladder wall as a part of an image analysis pipeline for CT urography (CTU).

MATERIALS AND METHODS

A data set of 172 CTU cases was collected retrospectively with Institutional Review Board (IRB) approval. The data set was randomly split into two independent sets of training (81 cases) and testing (92 cases) which were manually outlined for both the inner and outer wall. We trained a deep-learning convolutional neural network (DL-CNN) to distinguish the bladder wall from the inside and outside of the bladder using neighborhood information. Approximately, 240 000 regions of interest (ROIs) of 16 × 16 pixels in size were extracted from regions in the training cases identified by the manually outlined inner and outer bladder walls to form a training set for the DL-CNN; half of the ROIs were selected to include the bladder wall and the other half were selected to exclude the bladder wall with some of these ROIs being inside the bladder and the rest outside the bladder entirely. The DL-CNN trained on these ROIs was applied to the cases in the test set slice-by-slice to generate a bladder wall likelihood map where the gray level of a given pixel represents the likelihood that a given pixel would belong to the bladder wall. We then used the DL-CNN likelihood map as an energy term in the energy equation of a cascaded level sets method to segment the inner and outer bladder wall. The DL-CNN segmentation with level sets was compared to the three-dimensional (3D) hand-segmented contours as a reference standard.

RESULTS

For the inner wall contour, the training set achieved the average volume intersection, average volume error, average absolute volume error, and average distance of 90.0 ± 8.7%, -4.2 ± 18.4%, 12.9 ± 13.9%, and 3.0 ± 1.6 mm, respectively. The corresponding values for the test set were 86.9 ± 9.6%, -8.3 ± 37.7%, 18.4 ± 33.8%, and 3.4 ± 1.8 mm, respectively. For the outer wall contour, the training set achieved the values of 93.7 ± 3.9%, -7.8 ± 11.4%, 10.3 ± 9.3%, and 3.0 ± 1.2 mm, respectively. The corresponding values for the test set were 87.5 ± 9.9%, -1.2 ± 20.8%, 11.9 ± 17.0%, and 3.5 ± 2.3 mm, respectively.

CONCLUSIONS

Our study demonstrates that DL-CNN-assisted level sets can effectively segment bladder walls from the inner bladder and outer structures despite a lack of consistent distinctions along the inner wall. However, even with the addition of level sets, the inner and outer walls may still be over-segmented and the DL-CNN-assisted level sets may incorrectly segment parts of the prostate that overlap with the outer bladder wall. The outer wall segmentation was improved compared to our previous method and the DL-CNN-assisted level sets were also able to segment the inner bladder wall with similar performance. This study shows the DL-CNN-assisted level set segmentation tool can effectively segment the inner and outer wall of the bladder.

Dual-Energy CT Urography With 50% Reduced Iodine Dose Versus Single-Energy CT Urography With Standard Iodine Dose

OBJECTIVE

The purpose of this study was to compare dual-energy CT (DECT) urography with a 50% reduced iodine dose to single-energy CT (SECT) urography with a standard iodine dose with respect to attenuation of renal vascular and urinary tract structures and with respect to image quality.

SUBJECTS AND METHODS

The study included 62 patients undergoing evaluation of urinary tract lithiasis, tumor, or hematuria. Thirty-one patients underwent DECT urography with a 50% reduced iodine dose and reconstruction at 50 and 77 keV. These subjects were sex, age, and size matched to a group of 31 patients who underwent 120-kVp SECT urography with a standard iodine dose. The mean iodine dose was 22 g for DECT and 44 g for SECT. Attenuation was measured at seven locations in the renal arteries, renal veins, and urinary tract. Two reviewers subjectively scored the image quality parameters image noise, sharpness of urinary tract contours, enhancement of urinary structures, and streak artifacts.

RESULTS

Mean DECT attenuation at 50 keV was the same as or greater than SECT attenuation at each of the seven locations. Measured image noise was highest at 50-keV DECT but was the same for 77-keV DECT and 120-kVp SECT. Mean subjective scores for DECT image quality parameters were the same as or higher than those of SECT, except for streak artifact and sharpness of urinary tract contours.

CONCLUSION

DECT urography with a 50% reduced iodine dose may result in measured renal vascular and urinary tract attenuation the same as or higher than and image quality measurements and scores similar to those obtained with 120-kVp SECT urography with a standard iodine dose.

Comparison of Full- and Half-Dose Image Reconstruction With Filtered Back Projection or Sinogram-Affirmed Iterative Reconstruction in Dual-Source Single-Energy MDCT Urography

OBJECTIVE

The purpose of this study is to prospectively compare the image quality of and confidence in the presence of a lesion on CT urography images acquired using filtered back projection (FBP) with 100% and 50% radiation doses with those for images simultaneously acquired using sinogram-affirmed iterative reconstruction with strength 3 (SAFIRE) with 50% and 25% radiation doses for patients with a high risk for urothelial carcinomas.

SUBJECTS AND METHODS

A total of 150 patients randomly underwent CT urography examinations performed using a dual-source single-energy scanner. After the radiation output of each tube was adjusted, datasets at three radiation dose levels were reconstructed using FBP and SAFIRE. Seven radiologists subjectively assessed image quality and confidence in the presence of a lesion for a total of 1200 datasets. Nonparametric methods for cluster data were used to estimate AUC values for variance methods on the basis of a noninferiority margin of 0.05.

RESULTS

The mean AUC value for image quality in SAFIRE with a 25% radiation dose was significantly lower than that of FBP with 100% radiation dose (p < 0.05 for all). The mean AUC values for the presence of a lesion were 0.907 and 0.894 for FBP, respectively, at 100% and 50% radiation doses, respectively, and 0.900 and 0.799 for SAFIRE at 50% and 25% radiation doses, respectively. However, the image quality of images acquired with SAFIRE at a 25% radiation dose was significantly inferior to that of images acquired with FBP at a 100% radiation dose.

CONCLUSION

Regardless of the experience of the radiologist, CT urography images acquired with FBP and SAFIRE with a 50% radiation dose were noninferior to those acquired with FBP with a 100% radiation dose in terms of image quality and confidence in the presence of a lesion, whereas those acquired with SAFIRE with 25% radiation dose were inferior.

Bladder cancer diagnosis with CT urography: test characteristics and reasons for false-positive and false-negative results

PURPOSE

To determine test characteristics of CT urography for detecting bladder cancer in patients with hematuria and those undergoing surveillance, and to analyze reasons for false-positive and false-negative results.

METHODS

A HIPAA-compliant, IRB-approved retrospective review of reports from 1623 CT urograms between 10/2010 and 12/31/2013 was performed. 710 examinations for hematuria or bladder cancer history were compared to cystoscopy performed within 6 months. Reference standard was surgical pathology or 1-year minimum clinical follow-up. False-positive and false-negative examinations were reviewed to determine reasons for errors.

RESULTS

Ninety-five bladder cancers were detected. CT urography accuracy: was 91.5% (650/710), sensitivity 86.3% (82/95), specificity 92.4% (568/615), positive predictive value 63.6% (82/129), and negative predictive value was 97.8% (568/581). Of 43 false positives, the majority of interpretation errors were due to benign prostatic hyperplasia (n = 12), trabeculated bladder (n = 9), and treatment changes (n = 8). Other causes include blood clots, mistaken normal anatomy, infectious/inflammatory changes, or had no cystoscopic correlate. Of 13 false negatives, 11 were due to technique, one to a large urinary residual, one to artifact. There were no errors in perception.

CONCLUSION

CT urography is an accurate test for diagnosing bladder cancer; however, in protocols relying predominantly on excretory phase images, overall sensitivity remains insufficient to obviate cystoscopy. Awareness of bladder cancer mimics may reduce false-positive results. Improvements in CTU technique may reduce false-negative results.

Integration of CT urography improves diagnostic confidence of 68Ga-PSMA-11 PET/CT in prostate cancer patients

Background

To prove the feasibility of integrating CT urography (CTU) into ⁶⁸Ga-PSMA-11 PET/CT and to analyze the impact of CTU on assigning focal tracer accumulation in the ureteric space to either ureteric excretion or metastatic disease concerning topographic attribution and diagnostic confidence.

Methods

Ten prostate cancer patients who underwent ⁶⁸Ga-PSMA-11 PET/CT including CTU because of biochemical relapse or known metastatic disease were retrospectively analyzed. CTU consisted of an excretory phase 10 min after injection of 80 mL iodinated contrast material. Ureter opacification at CTU was evaluated using the following score: 0, 0% opacification; 1, < 50%; 2, 50–99%; 3, 100%. Topographic attribution and confidence of topographic attribution of focal tracer accumulation in the ureteric space were separately assessed for ⁶⁸Ga-PSMA-11 PET/CT without and with CTU. Diagnostic confidence was evaluated using the following score: 0, < 25% confidence; 1, 26–50%; 2, 51–75%; 3, 76–100%.

Results

At CTU, mean ureter opacification score was 2.6 ± 0.7. At ⁶⁸Ga-PSMA-11 PET/CT without CTU, mean confidence of topographic attribution of focal tracer accumulation was 2.5 ± 0.7 in total and 2.6 ± 0.7 for metastatic disease. At ⁶⁸Ga-PSMA-11 PET/CT with CTU, mean confidence of topographic attribution of focal areas of tracer accumulation was significantly higher with 2.9 ± 0.2 in total and 2.7 ± 0.9 for metastatic disease (p < 0.001). In 4 of 34 findings (12%) attribution to either ureteric excretion or metastatic disease was discrepant between ⁶⁸Ga-PSMA-11 PET/CT without and with CTU (n.s).

Conclusions

Integration of CTU into ⁶⁸Ga-PSMA-11 PET/CT is feasible and increases diagnostic confidence of assigning focal areas of tracer accumulation in the ureteric space to either metastatic disease or ureteric excretion.

Urinary bladder cancer staging in CT urography using machine learning

PURPOSE

To evaluate the feasibility of using an objective computer-aided system to assess bladder cancer stage in CT Urography (CTU).

MATERIALS AND METHODS

A dataset consisting of 84 bladder cancer lesions from 76 CTU cases was used to develop the computerized system for bladder cancer staging based on machine learning approaches. The cases were grouped into two classes based on pathological stage ≥ T2 or below T2, which is the decision threshold for neoadjuvant chemotherapy treatment clinically. There were 43 cancers below stage T2 and 41 cancers at stage T2 or above. All 84 lesions were automatically segmented using our previously developed auto-initialized cascaded level sets (AI-CALS) method. Morphological and texture features were extracted. The features were divided into subspaces of morphological features only, texture features only, and a combined set of both morphological and texture features. The dataset was split into Set 1 and Set 2 for two-fold cross-validation. Stepwise feature selection was used to select the most effective features. A linear discriminant analysis (LDA), a neural network (NN), a support vector machine (SVM), and a random forest (RAF) classifier were used to combine the features into a single score. The classification accuracy of the four classifiers was compared using the area under the receiver operating characteristic (ROC) curve (A_z ).

RESULTS

Based on the texture features only, the LDA classifier achieved a test A_z of 0.91 on Set 1 and a test A_z of 0.88 on Set 2. The test A_z of the NN classifier for Set 1 and Set 2 were 0.89 and 0.92, respectively. The SVM classifier achieved test A_z of 0.91 on Set 1 and test A_z of 0.89 on Set 2. The test A_z of the RAF classifier for Set 1 and Set 2 was 0.89 and 0.97, respectively. The morphological features alone, the texture features alone, and the combined feature set achieved comparable classification performance.

CONCLUSION

The predictive model developed in this study shows promise as a classification tool for stratifying bladder cancer into two staging categories: greater than or equal to stage T2 and below stage T2.

The safety and efficacy of MPR-CTU combined with precise intraoperative ultrasonography guided flexible ureteroscope in the treatment of renal cystic disease

The safety and efficacy of multi-planar reconstruction (MPR) image post-processing technique-computed tomography (CT) urography (CTU) combined with precise intraoperative ultrasonography guided flexible ureteroscope in renal cyst incision and drainage in the treatment of cystic diseases of kidney were evaluated. A total of 68 patients were randomly divided into control and observation group (n=34). All the patients were treated with renal cyst incision and drainage under flexible ureteroscope. The control group was under ultrasound guidance. The observation group was combined with MPR-CTU, the safety and efficacy was compared. There was no significant difference between the two groups in the success rate and the time of cyst treatment (P>0.05). The incidence of intraoperative and postoperative complications of the observation group was significantly lower than that of the control group. After 1 month follow-up, the total effective rate of the observation group was significantly higher than that of the control group, the difference was statistically significant (P<0.05). Conclusion MPR-CTU technique combined with intraoperative ultrasonography to guide cyst incision and drainage under flexible ureteroscope for renal cystic disease has a high safety and efficacy, and it is worthy of clinical application.

Determination of single-kidney glomerular filtration rate (GFR) with CT urography versus renal dynamic imaging Gates method

OBJECTIVES

To present a single-kidney CT-GFR measurement and compare it with the renal dynamic imaging Gates-GFR.

MATERIALS AND METHODS

Thirty-six patients with hydronephrosis referred for CT urography and 99mTc-DTPA renal dynamic imaging were prospectively included. Informed consent was obtained from all patients. The CT urography protocol included non-contrast, nephrographic, and excretory phase imaging. The total CT-GFR was calculated by dividing the CT number increments of the total urinary system between the nephrographic and excretory phase by the products of iodine concentration in the aorta and the elapsed time, then multiplied by (1- Haematocrit). The total CT-GFR was then split into single-kidney CT-GFR by a left and right kidney proportionality factor. The results were compared with single-kidney Gates-GFR by using paired t-test, correlation analysis, and Bland-Altman plots.

RESULTS

Paired difference between single-kidney CT-GFR (45.02 ± 13.91) and single-kidney Gates-GFR (51.21 ± 14.76) was 6.19 ± 5.63 ml/min, p<0.001, demonstrating 12.1% systematic underestimation with ±11.03 ml/min (±21.5%) measurement deviation. A good correlation was revealed between both measurements (r=0.87, p<0.001).

CONCLUSION

The proposed single-kidney CT-GFR correlates and agrees well with the reference standard despite a systematic underestimation, therefore it could be a one-stop-shop for evaluating urinary tract morphology and split renal function.

KEY POINTS

• A new CT method can assess split renal function • Only using images from CT urography and the value of haematocrit • A one-stop-shop CT technique without additional radiation dose.

Urinary bladder cancer staging in CT urography using machine learning

PURPOSE

To evaluate the feasibility of using an objective computer-aided system to assess bladder cancer stage in CT Urography (CTU).

MATERIALS AND METHODS

A dataset consisting of 84 bladder cancer lesions from 76 CTU cases was used to develop the computerized system for bladder cancer staging based on machine learning approaches. The cases were grouped into two classes based on pathological stage ≥ T2 or below T2, which is the decision threshold for neoadjuvant chemotherapy treatment clinically. There were 43 cancers below stage T2 and 41 cancers at stage T2 or above. All 84 lesions were automatically segmented using our previously developed auto-initialized cascaded level sets (AI-CALS) method. Morphological and texture features were extracted. The features were divided into subspaces of morphological features only, texture features only, and a combined set of both morphological and texture features. The dataset was split into Set 1 and Set 2 for two-fold cross-validation. Stepwise feature selection was used to select the most effective features. A linear discriminant analysis (LDA), a neural network (NN), a support vector machine (SVM), and a random forest (RAF) classifier were used to combine the features into a single score. The classification accuracy of the four classifiers was compared using the area under the receiver operating characteristic (ROC) curve (A_z ).

RESULTS

Based on the texture features only, the LDA classifier achieved a test A_z of 0.91 on Set 1 and a test A_z of 0.88 on Set 2. The test A_z of the NN classifier for Set 1 and Set 2 were 0.89 and 0.92, respectively. The SVM classifier achieved test A_z of 0.91 on Set 1 and test A_z of 0.89 on Set 2. The test A_z of the RAF classifier for Set 1 and Set 2 was 0.89 and 0.97, respectively. The morphological features alone, the texture features alone, and the combined feature set achieved comparable classification performance.

CONCLUSION

The predictive model developed in this study shows promise as a classification tool for stratifying bladder cancer into two staging categories: greater than or equal to stage T2 and below stage T2.

Diagnostic yield of CT urography in the evaluation of hematuria in young patients in a military population

PURPOSE

To assess the diagnostic yield of a computed tomography urography (CTU) study in patients less than 50 years of age, who have a history of military service, and who are at increased risk of urological cancers secondary to harmful practices and work-related exposures.

METHODS

137 Consecutive patients who underwent CTU between 2012 and 2013 for new onset of hematuria were included. Initial review of the clinical interpretations of the CTU studies grouped the studies into negative and positive exams for any urological findings. Review of the patients' medical records and subsequent radiology studies determined microscopic versus gross hematuria at presentation and any findings after their CTU study consistent with a urological malignancy. The positive exams were reviewed by second readers, blinded to the clinical interpretation of the initial CTU studies, who first read the unenhanced images. The readers characterized findings as visible on non-contrast CT alone or they requested contrast-enhanced images. Each urological finding was recorded for each patient.

RESULTS

Of the 137 included patients, 84 had micro-hematuria and 53 had gross hematuria. There were a total of 99 negative examinations of the 137 included patients. Contrast was requested 14 times to confirm 11 benign cysts. No findings concerning for malignancy were found by the readers or on subsequent record reviews for each patient.

CONCLUSION

An unenhanced CT may be appropriate to evaluate new onset microscopic, and possibly gross hematuria, in patients younger than 40, even in patients at increased risk of urologic cancer.

Split-Bolus Portal Venous Phase Dual-Energy CT Urography: Protocol Design, Image Quality, and Dose Reduction

OBJECTIVE

The purpose of this study is to evaluate the image quality of split-bolus portal venous phase urography and the potential reduction of radiation dose by using a second-generation dual-source dual-energy CT (DECT) scanner.

MATERIALS AND METHODS

DECT urography was performed in 84 patients. Unenhanced CT was performed 20 minutes after drinking 800 mL of water. The split-bolus protocol consisted of a sequence of injections, as follows: 200 mL of normal saline (2.0 mL/s), 50 mL of contrast medium (2.5 mL/s) at 0 second, 70 mL of contrast medium (2.5 mL/s) at 360 seconds, and a saline flush of 25 mL. The scan was started at 420 seconds. Virtual unenhanced images were reconstructed from contrast-enhanced images. The mean CT density and signal-to-noise ratio (SNR) of the renal parenchyma, vessels, upper urinary tract, normal reference tissues, and tumors were measured for image quantitative analysis. Image quality and opacification of the collecting systems were rated by two radiologists using 3- or 4-point scales.

RESULTS

The SNR of all measured sites, except the renal pelvis, showed a statistically significant correlation (p < 0.001) between the true unenhanced and virtual unenhanced images. The overall sensitivity of stone detection was 87.5% (28/32) in virtual unenhanced images. Image quality of the renal parenchyma, arteries, and veins was excellent in 59.5%, 75.0%, and 97.6% of cases, respectively. Opacification of the intrarenal collecting systems, proximal, middle, and distal ureters, and bladder was complete in 92.9%, 83.9%, 78.6%, 77.4%, and 26.2% of patients, respectively. Omitting the unenhanced scan can reduce the mean radiation dose from 15.6 to 6.7 mSv.

CONCLUSION

Portal venous phase split-bolus DECT urography provides sufficient image quality with potential to reduce radiation exposure.

CT Urography for Diagnosis of Upper Urinary Tract Urothelial Carcinoma: Are Both Nephrographic and Excretory Phases Necessary?

OBJECTIVE

The objective of our study was to compare the diagnostic performance of nephrographic phase only, excretory phase only, and both nephrographic and excretory phases of CT urography (CTU) for the detection of upper tract urothelial carcinoma.

MATERIALS AND METHODS

Forty-nine consecutive patients with pathologically proven upper tract urothelial carcinoma who underwent a single-bolus CTU examination were evaluated. Forty-nine control patients with normal findings on two CTU examinations performed at a 1-year interval were included. Two radiologists independently reviewed the 98 CTU examinations at three different sessions (nephrographic phase only, excretory phase only, and both nephrographic and excretory phases simultaneously) and rated the likelihood of the presence of a urothelial carcinoma in each segment of the renal collecting system and ureter using a 5-point scale. Sensitivity, specificity, and AUC of ROC curve were calculated per segment and per patient.

RESULTS

A total of 314 segments, 56 of which contained tumors, were evaluated. In the per-segment analysis for reviewers 1 and 2, the sensitivity, specificity, and AUC, respectively, were as follows: 88%, 98%, and 0.95 and 84%, 97%, and 0.94 for the nephrographic phase; 79%, 98%, and 0.91 and 89%, 98%, and 0.95 for the excretory phase; and 88%, 99%, and 0.95 and 89%, 99%, and 0.96 for the combined nephrographic and excretory phases. The AUC of the combined nephrographic and excretory phases was significantly higher than that of the nephrographic phase (per-patient analysis, reviewer 2) and that of excretory phase (per-segment analysis, reviewer 1) but was not significantly different in any other comparisons.

CONCLUSION

The nephrographic and excretory phases are complementary for the detection of upper tract urothelial carcinoma.

CT urography and hematuria: a retrospective analysis of 771 patients undergoing CT urography over a 1-year period

BACKGROUND

Computed tomography (CT) urography is now used in the work-up of patients with hematuria. The dose of contrast medium and radiation varies considerably between the different CT protocols.

PURPOSE

To study the disease prevalence in a consecutive group of patients with hematuria undergoing CT urography with a low dose of contrast medium and radiation.

MATERIAL AND METHODS

From 1 April 2007 to 31 March 2008, using the Radiological Information System (RIS) as well as electronic patient records, demographic data, reason for referral, and diagnosis were obtained for all patients undergoing CT urography due to hematuria. The patients were followed for 3 years.

RESULTS

A total of 771 patients had hematuria diagnosed at the time of referral. In 137 patients (18%), a tumor and / or a complex cyst was found in the urinary tract (renal, ureteral, or bladder), in 68 (9%) a calculi, in 118 (15%) other disease (i.e. infection or anomaly) was found. No abnormalities were found at CT urography in 455 (58%) of the patients with hematuria. Lesions were found more frequently in patients with visible hematuria than in patients with non-visible hematuria (48% vs. 29%). No malignant tumor or complex cyst was found in the kidneys or the ureters in patients with nonvisible hematuria.

CONCLUSION

CT urography with its low dose of contrast medium and radiation is a useful diagnostic imaging test for investigating patients with hematuria.

Sickle cell trait: not as benign as once thought

We describe a case of renal papillary necrosis in a middle-aged female with sickle cell trait who presented with gross hematuria. We wish to highlight this case for several reasons. Sickle cell trait is often viewed as a benign condition despite the fact that it is associated with significant morbidity such as renal papillary necrosis and renal medullary carcinoma. Appropriate evaluation needs to be undertaken to promptly diagnose renal papillary necrosis and differentiate it from renal medullary carcinoma as this can result in deadly consequences for patients. CT urography has emerged as a diagnostic study to evaluate hematuria in such patients. We review the pathophysiology, diagnosis, and management of renal papillary necrosis in patients with sickle cell trait.

CT evaluation of the upper urinary tract in adults younger than 50 years with asymptomatic microscopic hematuria: is IV contrast enhancement needed?

OBJECTIVE

The purpose of this study is to compare CT urography (CTU) with unenhanced CT in the evaluation of upper urinary tracts in adults younger than 50 years with asymptomatic microscopic hematuria.

MATERIALS AND METHODS

In this study, 1516 CTU examinations were reviewed in adults younger than 50 years. Inclusion criteria were no significant prior urologic disease and asymptomatic microscopic hematuria with at least one urinalysis with greater than or equal to 3 RBCs/high-power field and less than or equal to 50 RBCs/high-power field. Upper urinary tract findings on CTU were classified as malignancy-related or non-malignancy-related hematuria and incidental non-hematuria-related findings. A blinded radiologist reviewed the unenhanced images, recording upper urinary tract findings and recommendations for further contrast-enhanced imaging. The modified Wald equation at a 95% CI, the "Rule of Threes" equation, and binomial distribution were used for malignancy-related findings.

RESULTS

Four hundred forty-five examinations in 442 patients met inclusion criteria. CTU reports showed zero malignancy-related hematuria findings, 64 non-malignancy-related hematuria findings (62 renal calculi and two others), and 138 incidental non-hematuria-related findings. Unenhanced CT interpretation had a sensitivity of 100% (64/64) and a specificity of 89.2% (337/378). The theoretic risk of an upper urinary tract malignancy is 0-1.1%.

CONCLUSION

CTU added no additional diagnostic benefit versus unenhanced CT in evaluating the upper urinary tracts of adults younger than 50 years with asymptomatic microscopic hematuria. Using only unenhanced CT can reduce radiation and minimize contrast agent-associated risk, with a less than 1.0% risk of missing upper urinary tract hematuria-related malignancy.