Pictorial review: CT urography and virtual endoscopy: promising imaging modalities for urinary tract evaluation

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.

Computed tomography: important considerations for pediatric patients

Computed tomography plays a central and increasingly important role in medical imaging. From the very beginning more than 30 years ago, computed tomography technology has continued to develop and provide a wide variety of applications for evaluation of disorders of virtually any organ system in both children and adults. The benefits are particularly evident with the newer, fast, high-resolution multidetector scanners. However, these benefits must be carefully weighed against the potential risks, which include a relatively high radiation dose. Current research efforts are directed at both further improvements in the diagnostic potential with computed tomography, as well as managing radiation dose.

Computed tomography urography 1: techniques and technology

Contrast-enhanced computed tomography urography has become possible because of the development of multidetector technology, which has evolved to try and increase its diagnostic efficacy and reduce the radiation exposure. This review highlights important aspects of computed tomography urography as an imaging technique.

Detection of urothelial tumors: comparison of urothelial phase with excretory phase CT urography--a prospective study

PURPOSE

To compare contrast material-enhanced computed tomographic (CT) urography 60 seconds after injection of contrast material (urothelial phase [UP]) after intravenous administration of a diuretic with the standard 5-minute delayed excretory phase (EP) in a high-risk population for upper tract tumors.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Eighty CT urographic examinations in 77 patients known to have or at high risk for urothelial malignancy were included. After intravenous administration of a diuretic, dual-phase CT urography was performed at 60 seconds (UP) and 5 minutes (EP) after intravenous administration of contrast material. Two experienced abdominal radiologists independently interpreted each phase more than 1 month apart to minimize recall bias. Urinary tract distention and location and size of all lesions suspected of being urothelial tumors were recorded. Standard of reference was obtained from prospective study interpretation and surgical histopathologic findings. Generalized estimating equations for logistic regression were used to compare performance measures and adjust for the correlation of repeated measures within patients.

RESULTS

There were 23 upper and 61 lower urinary tract tumors confirmed in 15 and 32 patients, respectively. For detection of bladder tumors, there was higher sensitivity for the UP than the EP (89.3% [109 of 122] vs 70.5% [86 of 122], respectively; P<.0001). For detection of upper tract tumors, there was higher sensitivity for the UP than the EP (82.6% [38 of 46] vs 69.6% [32 of 46], respectively; P=.0194). Distention of all upper urinary tract segments was better during the EP than the UP (P<.0001).

CONCLUSION

UP CT urography after injection of a diuretic has a higher lesion detection rate than the EP for both upper and lower urinary tract tumors, which suggests its possible use as a single-phase protocol for evaluation of the entire urinary tract in patients at high risk for urothelial tumors.

[Diagnostic procedures in upper urinary tract urothelial carcinoma]

Upper urinary tract transitional cell carcinomas represent 5-6% of all urothelial carcinomas. Macroscopic hematuria is the most common symptom. The diagnostic algorithm contains medical history, clinical investigation, cystoscopy, urinary cytology, ultrasound and intravenous urography. When suspected, a complementary retrograde pyeloureterography with collecting selective urinary cytology is conducted. When radiological findings are doubted or when conservative treatment is planned, an ureterorenoscopy for biopsy of the suspected area is indicated. Computed tomography and magnetic resonance tomography is used to define the local extension of invasive tumors and to detect metastases. The use of urinary markers in the diagnosis of upper urinary tract urothelial carcinoma has to be evaluated in prospective trials.

Hematuria: portal venous phase multi detector row CT of the bladder--a prospective study

PURPOSE

To prospectively determine the accuracy of portal venous phase helical multi-detector row computed tomography (CT) for bladder lesion evaluation in patients with hematuria by using cystoscopy as the reference standard.

MATERIALS AND METHODS

The study was approved by the institutional review board for human investigation, and informed consent was obtained from all patients. This study included 118 patients (91 male, 27 female; age range, 15-87 years; mean age +/- standard deviation, 62 years +/- 14) who underwent portal venous phase multi-detector row CT (scanning delay, 70 seconds; section thickness, 2 mm) and conventional cystoscopy because of painless gross hematuria or recurrent microscopic hematuria. Two reviewers with different experience levels independently evaluated the bladder for lesions at CT in a prospective fashion. The kappa statistic was used to determine the per lesion and per patient agreement between the two reviewers and between the CT and cystoscopic findings. The sensitivity and specificity of multi-detector row CT for bladder lesion detection were analyzed for numbers of lesions and for numbers of patients.

RESULTS

Multi-detector row CT showed excellent per lesion (kappa = 0.839) and per patient (kappa = 0.881) agreement between the two reviewers. Respective per lesion and per patient agreement between the CT and cystoscopic findings was also excellent in the first (kappa = 0.866 and kappa = 0.881) and second (kappa = 0.802 and kappa = 0.863) reviewers. The sensitivity and specificity of multi-detector row CT were 89%-92% and 88%-97%, respectively, in the per lesion analysis and 95% and 91%-93%, respectively, in the per patient analysis for both reviewers. All statistical parameters of diagnostic accuracy were similar between the two reviewers (P > .05).

CONCLUSION

Portal venous phase multi-detector row CT can provide high accuracy and reader agreement for bladder lesion detection in patients with painless gross hematuria and recurrent microscopic hematuria; these results indicate that multi-detector row CT can be used as the initial bladder examination in such patients.

Applications of Computed Tomography in Renal Imaging

There have been huge advances in CT technology since its introduction more than 30 years ago. Modern, multislice CT scanners are fast and produce truly volumetric data, allowing it to be reconstructed in almost any plane. In this article, we explore the impact of these developments on the use of CT in imaging of the renal tract. Whilst it may take the radiologist longer to review and process the increased amount of data that is produced, diagnostic accuracy is unquestionably improved and new and exciting challenges are presented to the radiologist as he learns to manipulate and interpret the data in a way that he has never done before.

Multislice computed tomography-urography: intraindividual comparison of different preparation techniques for optimized depiction of the upper urinary tract in an animal model

OBJECTIVES

We sought to evaluate intraindividually 3 different preparation protocols for achieving improved opacification and anatomic depiction of the upper urinary tract in multisclice computed tomography urography (MSCTU) using a porcine model.

MATERIAL AND METHODS

MSCTU was performed in 8 healthy pigs. Each animal underwent 3 MSCT urographies using 3 different preparations before the injection of contrast material: A, intravenous (iv) saline (250 mL); B, iv low-dose furosemide (0.1 mg/kg); and C, iv saline (250 mL) plus iv low-dose furosemide (0.1 mg/kg). Image analysis was performed blinded to the applied protocols and included the evaluation of the opacification and anatomic depiction of the upper urinary tract by means of graded scales. Ureteral distension was determined and density was measured within the collecting system.

RESULTS

Furosemide significantly improved both mean opacification scores and mean scores of anatomic depiction compared with the exclusive infusion of saline for MSCTU. There was no significant difference between the application of furosemide and the combination of furosemide plus saline. A significant increase of 25-26% for ureteral distension was found when furosemide was applied. Significant lower mean attenuation values (Hounsfield units) and standard deviation were found within the opacified urine for diuretic-enhanced MSCTU.

CONCLUSIONS

Low-dose furosemide injection is superior to saline infusion for achieving optimal enhancement in MSCTU. It is not necessary to combine furosemide and saline infusion. In MSCTU, low-dose furosemide is a simple add-on simplifying image acquisition timing and removing the need for abdominal compression devices.

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

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

Comparison of Virtual Cystoscopy, Multiplanar Reformation, and Source CT Images with Contrast Material-Filled Bladder for Detecting Lesions

OBJECTIVE

The objective of our study was to compare the diagnostic accuracy of virtual cystoscopy, multiplanar reformation, and source CT images for lesion detection in the contrast material-filled bladder.

SUBJECTS AND METHODS

Two observers independently evaluated 47 patients (28 men and 19 women; mean age +/- SD, 59 +/- 16 years) with virtual cystoscopy, multiplanar reconstruction, and source CT images acquired with contrast material-filled bladder using an MDCT scanner (detector array, 4 x 1.25 mm; beam pitch, 0.75). Agreement between the two observers was evaluated for the three reconstruction methods using kappa statistics. Using the conventional cystoscopic findings as a reference, we compared the results of the three reconstruction techniques both by bladder site and by patient using the McNemar test.

RESULTS

The interobserver agreement for the number of positive sites was excellent for virtual cystoscopy (kappa = 0.816), fair for multiplanar reconstruction (kappa = 0.461), and good for source CT images kappa = 0.676). For both observers, the sensitivity for lesion detection by bladder site was significantly greater with virtual cystoscopy (observer 1, 95%; observer 2, 90%) than with multiplanar reconstruction (78% and 60%) and source CT (68% and 65%) images (p < 0.05), whereas the specificity by bladder site and the sensitivity and specificity by patient did not differ with the three methods (p > 0.05). For determining the presence or absence of lesion at each site, virtual cystoscopy was more accurate than multiplanar reconstruction and source CT images for both observers (p < 0.05).

CONCLUSION

Virtual cystoscopy is more accurate than multiplanar reconstruction and source CT images for the detection of lesions in the bladder.

Multidetector CT urography in imaging of the urinary tract in patients with hematuria

This review article comprehensively discusses multidetector CT urography protocols and their role in imaging of the urinary tract in patients with hematuria.