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

Role of Multiparametric MR Imaging in Malignancies of the Urogenital Tract

Multiparametric MR imaging (mpMRI) combine different sequences that, properly tailored, can provide qualitative and quantitative information about the tumor microenvironment beyond traditional tumor size measures and/or morphologic assessments. This article focuses on mpMRI in the evaluation of urogenital tract malignancies by first reviewing technical aspects and then discussing its potential clinical role. This includes insight into histologic subtyping and grading of renal cell carcinoma and assessment of tumor response to targeted therapies. The clinical utility of mpMRI in the staging and grading of ureteral and bladder tumors is presented. Finally, the evolving role of mpMRI in prostate cancer is discussed.

Diagnostic value of strain elastography for differentiation between renal cell carcinoma and transitional cell carcinoma of kidney

PURPOSE

The objective of our study was to prospectively evaluate the diagnostic performance of strain elastography for differentiation between renal cell carcinomas (RCCs) and transitional cell carcinomas (TCCs) of kidney.

METHODS

A total of 99 consecutive patients who were referred to our hospital because of a newly diagnosed solid renal mass suspicious for malignancy on radiological screenings were evaluated with sonography, including strain elastography. Strain elastography was used to compare the stiffness of the renal masses and renal cortex. The ratio of strain in a renal mass and nearby renal cortex was defined as the strain index value. Mean strain index values for RCCs and TCCs were compared, and mean strain index values between histological subtypes of RCC were also compared.

RESULTS

Although TCCs were smaller than RCCs (p < 0.001), there were no significant differences in gender distribution and mean age of the patients, and mean probe-tumor distance between RCC and TCC. The mean strain index value ±SD for TCC (5.18 ± 1.12) was significantly higher than the value for RCC (4.04 ± 0.72; p < 0.001). Mean strain index value for papillary cell carcinomas (4.09 ± 0.45) was slightly higher than that for clear cell carcinomas (3.85 ± 0.78): however, the difference was not statistically significant (p = 0.51).

CONCLUSIONS

Strain elastography can be used as a valuable imaging technique for preoperative differentiation between RCC and TCC of kidney.

DWI in the Etiologic Diagnosis of Excretory Upper Urinary Tract Lesions: Can It Help in Differentiating Benign From Malignant Tumors? A Retrospective Study of 98 Patients

OBJECTIVE

The objective of this study was to evaluate the diagnostic performance of high-field DWI in distinguishing benign from malignant lesions of the upper urinary tract (UUT).

MATERIALS AND METHODS

Ninety-eight patients who underwent 3-T DWI (b = 1000 s/mm(2)) for assessment of a UUT lesion were retrospectively included in the study. Data on the size, location, and mean apparent diffusion coefficient (ADC) value of the lesions were collected and correlated with the final diagnosis. ROC curve analysis was used to determine the best threshold value of the mean ADC for characterization of the lesions.

RESULTS

A total of 66 carcinomas and 33 benign lesions were identified. The mean (± SD) ADC value was statistically significantly lower for the malignant lesions than for the benign lesions (0.984 ± 0.048 vs 1.536 ± 0.067 × 10(-3) mm(2)/s; p = 0.000007). For characterization of malignant lesions, the best cutoff ADC value on the ROC curve was found to be less than or equal to 0.996 10(-3) mm(2)/s. On the basis of this value, the sensitivity and specificity of 3-T DWI for the identification of malignant UUT lesions were 78.3% and 95.5%, respectively, with a positive predictive value of 94.7% and a negative predictive value of 80.8% (p = 0.0001). The thickness of the smallest lesion was 3 mm. The mean ADC value of high-grade tumors was not statistically significantly lower than that of low-grade tumors. The best cutoff value for predicting benignancy was greater than or equal to 1.100 × 10(-3) mm(2)/s with sensitivity of 90.9%, specificity of 82.6%, positive predictive value of 83.3%, and negative predictive value of 90.5%.

CONCLUSION

The ADC measurement is a useful additional parameter in the differentiation of benign from malignant UUT lesions.

Magnetic Resonance Imaging of Perirenal Pathology

The perirenal space can be involved by a variety of neoplastic, inflammatory, infectious, and proliferative disorders. Magnetic resonance imaging is often an ideal technique for identification and staging of lesions arising within the perirenal space, with its superior soft tissue characterization as well as its ability to visualize extension into blood vessels and adjacent organs. This pictorial essay describes the magnetic resonance imaging appearance of a variety of pathologies which can arise from or involve the perirenal space, and provides a framework for categorization and differential diagnosis of these lesions.

Beyond ureterolithiasis: gamut of abnormalities affecting the ureter

Nephrolithiasis is the most common condition involving the ureters. However, various other entities can affect the ureters, albeit less frequently. Imaging plays a crucial role in diagnosis, management, and follow-up of ureteral pathology. In the past decade, computed tomography urography has replaced traditional methods of ureteral imaging due to its high spatial resolution, multiplanar imaging, and rapid acquisition time. More recently, magnetic resonance urography has also been explored in evaluating ureteral abnormalities. In this review, we briefly discuss current imaging techniques used in assessment of the ureters and present a diverse group of diseases affecting the ureters. We begin with primary and secondary ureteral malignancies, followed by uncommon infectious/inflammatory diseases that can involve the ureters including tuberculosis, xanthogranulomatous pyelonephritis, and graft-versus-host disease. We then discuss the imaging characteristics of endometriosis and retroperitoneal fibrosis as two important examples of pelvic and retroperitoneal processes that occasionally obstruct the ureters and present with clinical symptoms similar to that of renal stones. We end with a brief discussion of miscellaneous conditions that affect the ureters, including ureteral hemorrhage, ureteral intussusception, ureteral pseudodiverticulosis, Malacoplakia, and ureteritis cystica. Knowledge of these entities and their characteristic imaging manifestations along with patient's clinical presentation allows accurate diagnosis and timely patient management.

Comparison between computed tomography multislice and high-field magnetic resonance in the diagnostic evaluation of patients with renal masses

BACKGROUND

Renal masses are a common finding in diagnostic imaging; these lesions usually are solid or cystic, benign or malignant, and the correct diagnosis may be difficult. The aim of our study was the comparison of multi-slice computed tomography (MSCT) and high-field magnetic resonance (MR) in the diagnostic evaluation of renal masses.

METHODS

We studied 29 patients, 16 men and 13 women aged 8-85 years (mean 61±17 years) with histo-cytological diagnosis of renal masses (n=31), of which the majority (74%; n=23) was represented by malignant lesions [renal cell carcinoma (Ca) =16, chromophobe renal cell Ca =2, squamous cell Ca =1, urothelial Ca =2, lymphoma =1, Wilms tumor =1]; the remaining 8 masses (26%) were benign (pyelonephritis =2, simple cyst =1, hematic cyst =1, lipoma =1 and oncocytoma =3). All patients underwent MSCT and MR (3.0 Tesla) before and after contrast injection; the images were evaluated in double-blind by two expert radiologists. The results of the images were then compared with the histo-cytological data to calculate the values of diagnostic accuracy for both methods in the identification and characterization of renal masses. The benign or malignant nature of the lesions was established according to the regularity of the margins, presence or absence of significant contrast enhancement, infiltration of perirenal fat and vascular invasion. The concordance of the results of the two imaging techniques was then calculated using the coefficient Kappa Cohen.

RESULTS

For both identification and characterization of renal masses, MSCT and MR showed comparable values of diagnostic accuracy with a significant concordance (k=1); in particular, the diagnostic accuracy of MSCT/MR was 100%/100% for lesion identification, 90%/90% for lesion characterization in terms of benign or malignant nature, 97%/97% for the evaluation of lesion edges, 90%/90% for the assessment of lesion contrast enhancement, 93%/93% for the evaluation of peri-renal fat infiltration and 96%/96% for the evaluation of vascular infiltration. Only in three cases of oncocytoma the two imaging methods were both inaccurate for diagnosis of benignity classifying the lesions as probably malignant on the basis of the absence of central scar and of dynamic contrast enhancement pattern.

CONCLUSIONS

The results of our study show comparable diagnostic accuracy of computed tomography (CT) and MR for the identification and characterization of expansive renal lesions. High-field MR is, therefore, a valid alternative to MSCT in the evaluation of renal masses avoiding exposure to ionizing radiation.

"The creeping tumor:" An unusual presentation of upper urinary tract malignancy

Upper urinary tract urothelial malignancy accounts for 5-10% of urothelial carcinomas. Synchronous bladder carcinoma occurs in 2-4% of patients with upper urinary tract tumors. Urothelial malignancy involving the entire upper urinary tract is an extremely rare entity. Most upper urinary tract malignancies are transitional cell carcinomas (TCC), of which the sarcomatoid variant is very rare. These tumors pose a challenge to the radiologist. We herein report a case of TCC involving the entire collecting system of the left kidney, extending down along the ureter and projecting as a mass in the bladder.

The goblet sign

The purpose of this article is to describe the imaging appearance of the "goblet sign" and review the clinical significance of this sign.

Robot-assisted surgery for the treatment of upper urinary tract urothelial carcinoma

Robot-assisted laparoscopic surgery is increasingly used in urologic oncologic surgery. Robotic nephroureterectomy is still a relatively new technique. As upper tract urothelial carcinoma is a rare disease, intermediate- and long-term outcome data are scarce. However, robotic nephroureterectomy does seem to offer advantages to open and laparoscopic counterparts, with comparable short-term oncologic and functional outcomes. Here the authors review the robotic surgical management of upper tract urothelial carcinoma, with a review of the steps and tips on making this approach more widely adoptable.

Haematuria: an imaging guide

This paper discusses the current status of imaging in the investigation of patients with haematuria. The physician must rationalize imaging so that serious causes such as malignancy are promptly diagnosed while at the same time not exposing patients to unnecessary investigations. There is currently no universal agreement about the optimal imaging work up of haematuria. The choice of modality to image the urinary tract will depend on individual patient factors such as age, the presence of risk factors for malignancy, renal function, a history of calculus disease and pregnancy, and other factors, such as local policy and practice, cost effectiveness and availability of resources. The role of all modalities, including conventional radiography, intravenous urography/excretory urography, ultrasonography, retrograde pyelography, multidetector computed tomography urography (MDCTU), and magnetic resonance urography, is discussed. This paper highlights the pivotal role of MDCTU in the imaging of the patient with haematuria and discusses issues specific to this modality including protocol design, imaging of the urothelium, and radiation dose. Examination protocols should be tailored to the patient while all the while optimizing radiation dose.

MDCT evaluation of ureteral tumors: advantages of 3D reconstruction and volume visualization

OBJECTIVE

This article reviews the use of CT urography in diagnosing ureteral transitional cell carcinomas, different CT urography protocols, CT findings suggestive of ureteral malignancy, and the importance of 3D reconstructions.

CONCLUSION

The ureters can be problematic to evaluate on CT, partly because of difficulties in obtaining adequate ureteral distention and opacification. Proper diagnosis hinges not only on appropriate interpretation of the axial images but also on the utilization of a 3D technique (volume rendering or maximum intensity projection) as an ancillary tool.

Utility of MRI features in differentiation of central renal cell carcinoma and renal pelvic urothelial carcinoma

OBJECTIVE

The purpose of this article is to evaluate the utility of various morphologic and quantitative MRI features in differentiating central renal cell carcinoma (RCC) from renal pelvic urothelial carcinoma.

MATERIALS AND METHODS

Sixty patients (39 men and 21 women; mean [± SD] age, 65 ± 14 years; 48 with central RCC and 12 with renal pelvic urothelial carcinoma) who underwent MRI, including diffusion-weighted imaging (b values, 0, 400, and 800 s/mm(2)) and dynamic contrast-enhanced imaging, before histopathologic confirmation were included. Tumor T2 signal intensity and apparent diffusion coefficients (ADCs) were measured and normalized to muscle and CSF (hereafter referred to as normalized T2 signal and normalized ADC, respectively) and then were compared using receiver operating characteristic analysis. Also, two blinded radiologists independently assessed all tumors for various qualitative features, which were compared with the Fisher exact test and unpaired Student t test.

RESULTS

Urothelial carcinoma exhibited significantly lower normalized ADC than did RCC (p = 0.008), but no significant difference was seen in ADC or normalized T2 signal intensity (p = 0.247-0.773). Normalized ADC had the highest area under the curve (0.757); normalized ADC below an optimal threshold of 0.451 was associated with sensitivity of 83% and specificity of 71% for diagnosing urothelial carcinoma. Features that were significantly more prevalent in urothelial carcinoma included global impression of urothelial carcinoma, location centered within the collecting system, collecting system defect, extension to the ureteropelvic junction, preserved renal shape, absence of cystic or necrotic areas, absence of hemorrhage, homogeneous enhancement, and hypovascularity (all p < 0.033). Increased T1 signal intensity suggestive of hemorrhage was significantly more prevalent in RCC (p = 0.02). Interreader agreement for the subjective features ranged from 61.7% to 98.3%.

CONCLUSION

In addition to various qualitative MRI parameters, normalized ADC has utility in differentiating central RCC from renal pelvic urothelial carcinoma. Such differentiation may assist decisions regarding possible biopsy and treatment planning.

Transitional cell carcinoma of the upper urinary tract: optimizing image interpretation with 3D reconstructions

PURPOSE

This article reviews the pathophysiology of transitional cell carcinoma (TCC), CT urography (CTU) protocols, different possible 3D reconstruction techniques, and the importance of 3D reconstructions for appropriate interpretation.

RESULTS/CONCLUSION

CTU has largely replaced conventional IV pyelography in the evaluation of the upper urinary tract for TCC. The majority of large lesions can be easily seen on standard axial images with multiplanar reformats. However, it is imperative to also use 3D reconstructions when interpreting these studies, as subtle lesions can be difficult to visualize on the more traditional images. In this pictorial essay, we present multiple cases of upper urinary tract TCC which illustrate the value of 3D reconstructions for increasing the conspicuity of lesions, particularly at the junction of the infundibulum and calyx and in the ureters. As these cases demonstrate, each of the three possible 3D reconstruction techniques (maximum intensity projection, volume rendering, and volume rendered "virtual ureteroscopy") has its own distinct advantages, although the pitfalls of each technique must also be kept in mind.

Utility and diagnostic accuracy of ureteroscopic biopsy in upper tract urothelial carcinoma

CONTEXT

Ureteroscopic biopsy is the gold standard for the histopathologic diagnosis of urothelial carcinoma of the upper urinary tract.

OBJECTIVE

To assess the accuracy of endoscopically obtained biopsy samples in diagnosing, grading, and staging urothelial carcinoma and correlate diagnostic findings to biopsy sample size.

DESIGN

We retrospectively reviewed endoscopic biopsies of the ureter, renal pelvis, and ureteropelvic junction from 2008 to 2011. Biopsy diagnoses that were discordant with follow-up pathology and/or ureteroscopic impression were re-reviewed and samples were immunohistochemically analyzed.

RESULTS

Endoscopic biopsies (n = 118) yielded a sensitivity of 85.4% for the ureter (n = 79), 77.8% for the renal pelvis (n = 37), and 100% for the ureteropelvic junction (n = 2). A specificity of 100% for all locations and a diagnostic accuracy of 98.3% were identified. The median sample size was 0.3 cm for true positives, 0.3 cm for true negatives, and 0.2 cm for false negatives with no statistical significance. We found that 87.1% of tumors diagnosed on biopsy had concordant grade and 60.0% had concordant pT stage with follow-up surgical resections (n = 43) and biopsies (n = 24). Biopsy samples with concordant tumor grades (mean = 0.6 cm) compared with follow-up resection were larger than biopsy samples with discordant grades (mean = 0.3 cm) (P = .04).

CONCLUSIONS

Though highly specific, endoscopic biopsy does provide a significant false-negative rate owing to both sampling and diagnostic errors when assessing the upper urinary tract for urothelial carcinoma. Tumor grading is accurate, particularly with larger tissue samples, but tumor staging is unreliable.

Evaluation of renal urothelial carcinoma by contrast-enhanced ultrasonography

PURPOSE

To observe ultrasonographic features of urothelial carcinoma in renal pelvis and evaluate contrast-enhanced ultrasound (CEUS) in diagnosis.

MATERIALS AND METHODS

Fifty-two patients with urothelial carcinoma underwent preoperative conventional US, colour Doppler flow imaging (CDFI) and CEUS.

RESULTS

Of 52 total lesions, 41 (78.8%) could be clearly identified by US, and 49 (94.2%) were enhanced by CEUS. Among US-imaged lesions, 39 (95.1%) were solid tumours, and two (4.9%) were mixed solid-cystic; 25 (61.0%) were isoechoic, 11 (26.8%) hypoechoic, and five (12.2%) hyperechoic. Analysis of tumour blood flow by CDFI characterised 17 avascular lesions (41.5% of total), 16 hypovascular (39.0%), and 8 hypervascular (19.5%). The resistance index ranged from 0.65 to 0.88 (mean of 0.71). Enhancement was seen in 49 lesions after injection of SonoVue. A slow enhancement pattern was observed in 36 lesions (73.5%) relative to renal cortex, and 13/49 (26.5%) showed simultaneous enhancement. At peak enhancement, 38 lesions (77.6%) were hypo-enhanced, six (12.2%) iso-enhanced, and five (10.2%) hyper-enhanced. There were 12 lesions with intertumoural necrosis or haemorrhage (24.5%) that were heterogeneously enhanced, and 37 (75.5%) were homogeneously enhanced. A fast washout pattern was observed in 46 lesions (93.9%), synchronous washout in two (4.08%), and slow washout in one (2.04%).

CONCLUSIONS

Slow-in, fast-out, and hypo-enhancement properties are associated with renal urothelial carcinoma and may thus have diagnostic value. We found that CEUS is able to identify tumours that are ambiguous by conventional US, and it thus significantly improves the confidence of diagnosis.

Common and less-common renal masses and masslike conditions

As an increasing number of imaging examinations are performed, a greater number of incidental renal lesions are detected. Apart from the usual cysts and solid renal cell carcinomas, a variety of unusual benign and malignant renal lesions exist. Imaging is invaluable in characterizing these lesions and is confirmatory in some benign lesions. Renal cell carcinoma remains the diagnosis of exclusion; however, assessment of the imaging pattern in the appropriate clinical context can improve diagnostic accuracy. The objective of this article is to familiarize the radiologist with the imaging appearance of unusual non-neoplastic and neoplastic lesions and correlate with histopathologic studies when available.

Accuracy of photodynamic diagnosis in the detection and follow-up of patients with upper urinary tract lesions: Initial 3-year experience

Objective

To assess the diagnostic accuracy of photodynamic diagnostic (PDD) ureterorenoscopy for detecting upper-urinary tract transitional cell carcinoma (UUT-TCC) in our initial 3 years, and compare the results with that of white light ureterorenoscopy (WLU).

Patients and methods

Between August 2007 and March 2010, 32 patients underwent PDD flexible ureterorenoscopy for UUT-TCC. Oral 5-aminolaevulinic acid (5-ALA) was used as the photosensitiser. The sensitivity, specificity and detection rate of PDD were calculated.

Results

The sensitivity, specificity, positive and negative predictive values of PDD for detecting abnormal tissue were 96%, 100%, 100% and 88%, compared to the results of WLU of 80%, 86%, 95% and 55%, respectively. PDD was able to detect 96% (24/25) of the abnormal tissue and 96% (21/22) of cancerous tissue, while WLU detected 80% (20/25) of abnormal tissue and 91% (20/22) of the tumour tissue. Three patients of the 32 (10%) developed side-effects related to 5-ALA; two patients developed a facial-skin photosensitive reaction and one developed hypotension. All were treated conservatively, with no long-term effects.

Conclusion

PDD can be used safely in the UUT, and with a higher sensitivity, specificity and detection rate than standard WLU for detecting UUT tumours.

Preoperative hydronephrosis: independent predictor for changes in renal function following nephroureterectomy

OBJECTIVE

Partial or complete urinary obstruction caused by a tumor itself may affect renal function and the eligibility for perioperative cisplatin-based chemotherapy in patients with upper tract urothelial carcinoma. We investigated whether the status of preoperative hydronephrosis provides additional predictive information concerning changes in perioperative renal function.

METHODS

A total of 155 patients who underwent nephroureterectomy for upper tract urothelial carcinoma from 1997 to 2010 were identified. The association between preoperative parameters including the grade of hydronephrosis and perioperative renal function was analyzed.

RESULTS

Hydronephrosis was observed in 104 patients. The grade of hydronephrosis was 1, 2, 3 and 4 in 6 (3.9%), 25 (16.1%), 42 (27.1%) and 31 (20.0%) cases. Using a defined cut-off creatinine clearance value of ≥50 ml/min indicating eligibility for cisplatin-based chemotherapy, only 94 patients (60.6%) were eligible in the neoadjuvant setting. Of these 94 patients, 30 (31.9%) were judged to be ineligible in the adjuvant setting. Multivariate analysis demonstrated that patient age ≥70 years [P < 0.001, hazard ratio (HR) 27.9] and the absence of a higher grade hydronephrosis (P = 0.013, HR 7.40) were independent risk factors for predicting patients ineligible to receive adjuvant cisplatin-based chemotherapy. The proportion of patients ineligible to receive cisplatin-based chemotherapy changed from 40.9 to 88.6% following nephroureterectomy in patients aged ≥70 years and those with no or a lower grade hydronephrosis.

CONCLUSIONS

The status of hydronephrosis is an independent predictor of eligibility to receive adjuvant cisplatin-based chemotherapy. The information on preoperative hydronephrosis and patient age may assist in part of the decision-making when considering neoadjuvant cisplatin-based chemotherapy.

Surgical management for upper urinary tract transitional cell carcinoma

BACKGROUND

Upper tract transitional cell carcinomas (TCC) are uncommon and aggressive tumours. There are a number of surgical approaches to manage this condition including open radical nephroureterectomy and laparoscopic procedures.

OBJECTIVES

To determine the best surgical management option for upper tract transitional cell carcinoma.

SEARCH STRATEGY

A sensitive search strategy was developed to identify relevant studies for inclusion in this review. The following databases were searched for randomised trials evaluating surgical approaches to the management of upper tract TCC: Medline EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, British Nursing Index, AMED, LILACS, Web of Science®, Scopus, Biosis, TRIP, Biomed Central, Dissertation Abstracts, and ISI Proceedings.

SELECTION CRITERIA

The following criteria that were considered for this review.Types of studies - All randomised or quasi-randomised controlled trials comparing the various surgical methods and approaches for the management of localised upper tract transitional cell carcinoma. Types of participants - All adult patients with localised transitional cell carcinoma. Localised disease was defined as limited to the kidney or ureter with no gross regional lymph nodal enlargement on imaging. Types of interventions - Any surgical method or approach for managing localised upper tract transitional cell carcinoma. Types of outcome measures - Overall and cancer-specific survival were primary outcomes. Surgery-related morbidity. Quality of life and health economics outcomes were secondary outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors examined the search results independently to identify trials for inclusion.

MAIN RESULTS

We identified one randomised controlled trial that met our inclusion criteria. The trial showed that the laparoscopic approach had superior peri-operative outcomes compared to open approach. Laparoscopic was superior and statistically significant for blood loss (104 mL (millilitres) versus 430 mL, P < 0.001) and mean time to discharge (2.3 days versus 3.7, P < 0.001). Oncological outcomes (bladder tumour-free survival, metastasis-free survival, cancer-specific survival curves), at a median follow up of 44 months and in organ-confined disease, were comparable for both groups.

AUTHORS' CONCLUSIONS

There is no high quality evidence available from adequately controlled trials to determine the best surgical management of upper tract transitional cell carcinoma. However, one small randomised trial and observational data suggests that laparoscopic approach is associated with less blood loss and early recovery from surgery with similar cancer outcomes when compared to open approach.

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

OBJECTIVE

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

SUBJECTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Three-dimensional imaging of ureter with endoscopic optical coherence tomography

OBJECTIVES

To verify the ability to identify the layered structures of the ureteral wall and to image a segment of the ureter in 3 dimensions with high-speed, endoscopic optical coherence tomography (EOCT).

METHODS

We imaged a porcine ureter ex vivo using a spectral-domain EOCT with a specially designed circumferential scanning fiber catheter. The images were correlated with the histologic findings to identify the corresponding structures. Three-dimensional images and en face images at different depths from the luminal surface were reconstructed from the multiple cross-sectional images to visualize the layered structure of a segment of the ureter from different perspectives.

RESULTS

The EOCT images clearly revealed all layers of the ureteral wall as shown in the histologic images. In particular, with the specially designed fiber catheter, the light beam was well centered during the rotation and pull back, allowing constant acquisition of high-fidelity images and unambiguous identification of the smooth muscle layers in all images. With high-speed EOCT, a segment of ureter (20 mm) can be imaged in <90 seconds at a high resolution.

CONCLUSIONS

With its ability to visualize all layers of the ureteral wall, EOCT offers the potential to stage urothelial cancers that have infiltrated the muscular wall (Stage T2). This information will be complimentary to the diagnostic information obtained through ureteroscopic biopsy and computed tomography urogram.