Computed Tomographic Urography Update: An Evolving Urinary Tract Imaging Modality

Upper urinary tract urothelial carcinoma on multidetector CT: spectrum of disease

Urothelial carcinoma of the upper urinary tract (UUT) is a relatively uncommon genitourinary malignancy, accounting for about 5-7% of urothelial tumors. The significant features of this tumor are multifocality and high rate of recurrence. Computed tomography urography (CTU) has replaced excretory urography (EU) and retrograde pyelography (RP) for imaging of upper tract urothelial carcinoma. While many studies have confirmed high sensitivity (88-100%) and specificity (93-100%) of CTU, an optimized CT protocol is of critical importance in screening, staging, and post-operative follow-up of patients (Chlapoutakis, Eur J Radiol 73(2):334-338, 2010; Caoli and Cohan, Abdom Radiol (NY) 41(6):1100-1107, 2016). The key element of the CT protocol is to have adequate distension of the collecting system with excreted contrast, to detect subtle lesions at an early stage. In this article, we discuss the background of upper urinary tract TTC, pathogenesis, CT protocol and the role of imaging in evaluation of this malignancy, staging, as well as different imaging appearances.

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.

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.

Urinary bladder: normal appearance and mimics of malignancy at CT urography

The objective of this review article is to learn how to recognize anatomic variants and benign entities that mimic bladder cancer at computed tomography (CT) urography. Building on recent data that suggest that CT urography can be used to diagnose bladder cancer, recognition of anatomic variants and benign entities will help improve radiologists’ ability to diagnose bladder cancer.