Upper and Lower Tract Urothelial Imaging Using Computed Tomography Urography

Role of Multidetector Computed Tomography Urography in the Evaluation of Obstructive Uropathy: A Review

Obstructive uropathy, a prevalent clinical problem, can irreparably harm the kidneys if not treated promptly. As a result, accurate diagnosis is necessary for prompt management. This study examines the utility of multidetector computed tomography (MDCT) urography in identifying obstructive uropathy. PubMed, Google, Embase, Medline, and other electronic databases were used to search the English-language literature. The search phrases were obstructive urinary infections or urinary bladder or kidneys or MDCT. The authors' expertise and experience in the subject area aided in archiving pertinent publications. Even though the dilated upper tract of the ureters can be seen, ultrasonography (USG) has limitations because it cannot show the middle portion of the ureters, even if they are dilated mostly due to bowel gas artifacts. The USG does not emphasize the functioning of the renal tract. To evaluate obstructive uropathy, MDCT urography plays a very important role. For speedy, effective therapy, it provides a quick diagnosis of the source of obstruction.

Cornerstones of CT urography: a shared document by the Italian board of urogenital radiology

CT urography is a single term used to refer to different scanning protocols that can be applied for a number of clinical indications. If, on the one hand, this highlights the role of the radiologist in deciding the most suitable technique to perform according to the patient's needs, on the other hand, a certain confusion may arise due to the different technical and clinical variables that have to be taken into account. This has been well demonstrated by a previous work based on an online questionnaire administered to a population of Italian radiologists that brought out similarities as well as differences across the national country. Defining precise guidelines for each clinical scenario, although desirable, is a difficult task to accomplish, if not even unfeasible. According to the prementioned survey, five relevant topics concerning CT urography have been identified: definition and clinical indications, opacification of the excretory system, techniques, post-processing reconstructions, and radiation dose and utility of dual-energy CT. The aim of this work is to deepen and share knowledge about these main points in order to assist the radiology in the daily practice. Moreover, a synopsis of recommendations agreed by the Italian board of genitourinary imaging is provided.

CT of the urinary tract revisited

Computed tomography (CT) of the abdomen is usually appropriate for the initial imaging of many urinary tract diseases, due to its wide availability, fast scanning and acquisition of thin slices and isotropic data, that allow the creation of multiplanar reformatted and three-dimensional reconstructed images of excellent anatomic details. Non-enhanced CT remains the standard imaging modality for assessing renal colic. The technique allows the detection of nearly all types of urinary calculi and the estimation of stone burden. CT is the primary diagnostic tool for the characterization of an indeterminate renal mass, including both cystic and solid tumors. It is also the modality of choice for staging a primary renal tumor. Urolithiasis and urinary tract malignancies represent the main urogenic causes of hematuria. CT urography (CTU) improves the visualization of both the upper and lower urinary tract and is recommended for the investigation of gross hematuria and microscopic hematuria, in patients with predisposing factors for urologic malignancies. CTU is highly accurate in the detection and staging of upper tract urothelial malignancies. CT represents the most commonly used technique for the detection and staging of bladder carcinoma and the diagnostic efficacy of CT staging improves with more advanced disease. Nevertheless, it has limited accuracy in differentiating non-muscle invasive bladder carcinoma from muscle-invasive bladder carcinoma. In this review, clinical indications and the optimal imaging technique for CT of the urinary tract is reviewed. The CT features of common urologic diseases, including ureterolithiasis, renal tumors and urothelial carcinomas are discussed.

Split vs. Single Bolus CT Urography: Comparison of Scan Time, Image Quality and Radiation Dose

The purpose of this study was to compare the scan time, image quality and radiation dose of CT urograms (CTU) using a split vs. single bolus contrast media injection technique. A total of 241 consecutive CTUs performed between August 2019-February 2020 were retrospectively reviewed. There were three study groups: Group 1, <50 years old, 50/80 cc split-bolus administered at 0 and 700 s post initiation of injection, with combined nephrographic and excretory phases; group 2, ≥50 years old, same split-bolus protocol; and group 3, ≥50 years old, 130 cc single bolus injection, with nephrographic and excretory phases acquired at 100 s and 460 s post injection initiation. The recorded data elements were scan time, number of excretory phases, imaging quality based on opacification of the urinary collecting system (<50%, 50–75%, 75–100%), and dose-length product (DLP). Associations between group and categorical variables were assessed (Chi-square); mean scan time and DLP were compared (one-way ANOVA). Following analysis, proportionally fewer CTUs required a repeat excretory phase in group 3 (32/112, 28.6%) than in groups 1 (25/48, 52.1%) and 2 (37/80, 46.3%) (p = 0.006). Mean scan time was significantly lower in group 3 (678 s) than in groups 1 (1046 s) and 2 (978 s) (p < 0.0001). There was no association between groups and image quality (p = 0.13). DLP was higher in group 3 (1422 ± 837 mGy·cm) than in groups 1 (1041 ± 531 mGy·cm) and 2 (1137 ± 646 mGy·cm) (p = 0.003). In conclusion, single bolus CTU resulted in significantly fewer repeat phases and faster scan time at the expense of a slightly higher radiation dose.

Ureteral cancer: Complete ureteral obstruction on computed tomography urography is associated with periureteral fat invasion

OBJECTIVE

To determine predictive factors for periureteral fat invasion of ureteral cancer on computed tomography (CT) urography.

MATERIALS AND METHODS

Consecutive 77 patients with CT urography and surgically proven ureteral cancer were retrospectively evaluated. Three independent radiologists with different experiences in interpreting CT urography analyzed radiologic findings as follows: (a) periureteral infiltration (absent; equivocal; or present); (b) ureteral obstruction (complete obstruction or not); (c) lesion length; (d) lesion width; (e) hydronephrosis grade; and (f) renal atrophy (present or not). We analyzed univariate and multivariate logistic regression. We assessed sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of significant parameters.

RESULTS

Periureteral fat invasion was surgically identified in 33.8 % (26/77). For reader 1, periureteral infiltration (odds ratio [OR] = 3.330), complete ureteral obstruction (OR = 18.965), and renal atrophy (OR = 3.116) were significant in univariate analysis (p < 0.05), while only complete ureteral obstruction was significant in multivariate analysis (OR = 12.779; p = 0.018). For reader 2 (OR = 4.172; p = 0.019) and 3 (OR = 9.459; p = 0.035), only complete ureteral obstruction was significant in univariate analysis. Sensitivity, specificity, PPV, and NPV of complete ureteral obstruction were 96.2 % (25/26), 43.1 % (22/51), 46.3 % (25/54), and 95.7 % (22/23) for reader 1, 84.6 % (22/26), 43.1 % (22/51), 43.1 % (22/51), and 84.6 % (22/26) for reader 2, and 96.2 % (25/26), 27.5 % (14/51), 40.3 % (25/62), and 93.3 % (14/15) for reader 3, respectively.

CONCLUSION

Complete ureteral obstruction on CT urography is highly sensitive for extra-ureteral extension of ureteral cancer. Ureteral cancer without complete ureteral obstruction may be less likely to invade periureteral fat.

Optimal timing of delayed excretory phase computed tomography scan for diagnosis of urinary extravasation after high-grade renal trauma

BACKGROUND

Excretory phase computed tomography (CT) scan is used for diagnosis of renal collecting system injuries and accurate grading of high-grade renal trauma. However, optimal timing of the excretory phase is not well established. We hypothesized that there is an association between excretory phase timing and diagnosis of urinary extravasation and aimed to identify the optimal excretory phase timing for diagnosis of urinary extravasation.

METHODS

The Genito-Urinary Trauma Study collected data on high-grade renal trauma (grades III-V) from 14 Level I trauma centers between 2014 and 2017. The time between portal venous and excretory phases at initial CT scans was recorded. Poisson regression was used to measure the association between excretory phase timing and diagnosis of urinary extravasation. Predictive receiver operating characteristic analysis was used to identify a cutoff point optimizing detection of urinary extravasation.

RESULTS

Overall, 326 patients were included; 245 (75%) had excretory phase CT scans for review either initially (n = 212) or only at their follow-up (n = 33). At initial CT with excretory phase, 46 (22%) of 212 patients were diagnosed with urinary extravasation. Median time between portal venous and excretory phases was 4 minutes (interquartile range, 4-7 minutes). Time of initial excretory phase was significantly greater in those diagnosed with urinary extravasation. Increased time to excretory phase was positively associated with finding urinary extravasation at the initial CT scan after controlling for multiple factors (risk ratio per minute, 1.15; 95% confidence interval, 1.09-1.22; p < 0.001). The optimal delay for detection of urinary extravasation was 9 minutes.

CONCLUSION

Timing of the excretory phase is a significant factor in accurate diagnosis of renal collecting system injury. A 9-minute delay between the early and excretory phases optimized detection of urinary extravasation.

LEVEL OF EVIDENCE

Diagnostic tests/criteria study, level III.

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.

[Influence of immunomodulators on urological imaging]

BACKGROUND

Immune checkpoint inhibitors (ICI) have led to great advances in the therapy of metastatic renal cell and urothelial carcinoma. Currently ICI are approved for the first-line therapy of cisplatin-unfit patients (Atezolizumab, Pembrolizumab) and second-line therapy in patients with metastasized urothelial cancer (Atezolizumab, Nivolumab, Pembrolizumab). For the therapy of metastasized RCC, Nivolumab is approved as a second-line therapy and in combination with the CTLA‑4 antibody Ipilimumab as a first-line therapy.

OBJECTIVES

What does the optimized radiological follow-up and therapy response assessment for ICI, which differ in their pathways from common chemotherapeutics and anti-angiogenetic drugs, look like? What strategies are needed to meet the upcoming challenges concerning interpretation of the acquired images?

METHODS

A systematic literature search was carried out for urothelial and renal cell carcinoma.

RESULTS

Immune-related response criteria have been introduced to better characterize the imaging changes occurring under ICI, as monitoring response to immunotherapy still relies on RECIST.

CONCLUSIONS

To properly identify and predict response after treatment with ICI, additional studies with long-term follow-ups are needed. Because of the growing use of ICI, radiologists and urologist should be familiar with common imaging findings (such as pseudo progress) under immunotherapy to correctly interpret these findings in daily routine.

Diagnostic Utility of UroVysion Combined With Conventional Urinary Cytology for Urothelial Carcinoma of the Upper Urinary Tract

OBJECTIVES

We prospectively evaluated the utility of UroVysion in urothelial carcinomas of the upper urinary tract (UCUUTs).

METHODS

Ninety patients who received nephroureterectomy for UCUUT were enrolled. We performed urinary cytology and UroVysion before nephroureterectomy. We also performed the assays on 23 volunteers without a history of urothelial carcinoma.

RESULTS

Seventy-five high-grade urothelial carcinomas (HGUCs), 10 low-grade urothelial carcinomas, and five other conditions were enrolled. Sensitivity, specificity, positive predictive value, and negative predictive value for HGUC detection by urinary cytology were 28.0%, 100.0%, 100.0%, and 31.6%, respectively; for detection by fluorescence in situ hybridization, these values were 60.0%, 84.0%, 93.8%, and 41.2%, respectively. UroVysion detected the only deletion of 9p21 in eight of 23 samples negative for HGUC by urinary cytology and in three of 23 volunteers.

CONCLUSIONS

Combining urinary cytology and UroVysion can improve the diagnostic accuracy of UCUUT. Caution is advised in diagnosing UCUUT based only on deletion of 9p21.

Imaging response assessment of immunotherapy in patients with renal cell and urothelial carcinoma

PURPOSE OF REVIEW

Recent advances in anticancer immunotherapy have revolutionized the treatment of metastatic renal cell (RCC) and urothelial carcinoma. In this review, we discuss the mechanisms of action of these new therapeutic approaches, explicate the common adverse events, and highlight different imaging-based response criteria.

RECENT FINDINGS

The recent introduction of immune-checkpoint inhibitors led to substantial advances in therapy of metastatic RCC and urothelial carcinoma. Because of the distinct effector mechanisms of these new substances, atypical response patterns such as transient enlargements of tumor lesions, appearance of new lesions after therapy, no measurable decrease in tumor size, or delayed responses are observed in medical imaging studies. This indicates that the established imaging-based response assessment according to the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines has shortcomings to comprehensively evaluate treatment effects.

SUMMARY

While monitoring response to immunotherapy still relies on RECIST criteria, immune-related response criteria have been established to better address the imaging changes occurring under immunotherapy. Further studies with long-term follow-up are needed to properly identify and predict response after treatment beyond progression. Because of the expanding clinical use of immune checkpoint inhibitors, radiologists, urologist, and oncologists should be familiar with common imaging findings under this respective therapy.

Kidney, Ureteral, and Bladder Cancer: A Primer for the Internist

Malignancies of the urinary tract (kidney, ureter, and bladder) are distinct clinical entities. Hematuria is a unifying common presenting symptom for these malignancies. Surgical management of localized disease continues to be the mainstay of treatment, and early detection is important in the prognosis of disease. Patients often require life-long follow-up and assessment for recurrence.

Upper tract urothelial cancer

While urothelial carcinoma is a very common tumor, involvement of the upper tract is relatively uncommon. Consequently, there are no consensus imaging recommendations for upper tract disease. CT urography is the dominant imaging modality for the upper tract, but despite its excellent performance characteristics and being widely accepted as standard of care there is great variability in how CTU exams are performed across practices. MR urography has limited current application, but has the potential to become more mainstream in the future with continued technical advances. Upper tract urothelial carcinoma can manifest as a variety of appearances: a papillary lesion, focal wall thickening, focal enhancement, or as an infiltrative lesion. Pelvicalyceal location is about twice as common as in the ureter. Tumors in the pelvicalyceal location often manifest as an irregular enhancing soft tissue attenuation filling defect, and may be sessile or polypoid in morphology. Within the ureter, 73% are located in the distal segment.