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

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.

CT-urography: a nationwide survey by the Italian Board of Urogenital Radiology

Computed tomography-urography is currently the imaging modality of choice for the assessment of the whole urinary tract, giving the possibility to detect and characterize benign and malignant conditions. In particular, computed tomography-urography takes advantage from an improved visualization of the urinary collecting system due to acquisition of delayed scan obtained after excretion of intravenous contrast medium from the kidneys. Nevertheless, the remaining scans are of great help for identification, characterization, and staging of urological tumors. Considering the high number of diseases, urinary segment potentially involved and patients' features, scanning protocols of computed tomography-urography largely vary from one clinical case to another as well as selection and previous preparation of the patient. According to the supramentioned considerations, radiation exposure is also of particular concern. Italian radiologists were asked to express their opinions about computed tomography-urography performance and about its role in their daily practice through an online survey. This paper collects and summarizes the results.

Multimodality Imaging Findings Postcystectomy: Postoperative Anatomy, Surgical Complications, and Surveillance Imaging

Various surgical techniques exist for urinary diversion post cystectomy and each have different imaging features. This diverse range of surgical procedures can make imaging interpretation difficult and so familiarity with the postoperative anatomy is essential. Multiple imaging modalities and techniques are available for the radiologist's assessment including fluoroscopic studies, computed tomography, magnetic resonance, and radionuclide imaging. Knowledge of when each of these modalities is indicated and the typical imaging appearances is essential for early identification of postoperative complications and detection of tumor recurrence. This information enables the radiologist to make an accurate and early diagnosis and subsequently guide the management pathway for these patients.

Korean ureter length: A computed tomography-based study

Purpose

We measured ureter length in healthy Koreans using reformatted computed tomography (UL_CT) and found ways to indirectly estimate ureter length by measuring LL_CT, the length between the ureteropelvic junction and the ureterovesical junction, and standing and sitting height.

Materials and Methods

A total of 508 ureters of 254 healthy patients (median age, 55.0 years; 148 males and 106 females) were included in this retrospective study. UL_CT, LL_CT, and sitting and standing body height were measured.

Results

The mean left and right UL_CT were 25.2±2.2 and 25.0±2.2 cm, respectively. The mean left and right LL_CT were 21.1±1.8 and 20.3±1.9 cm, respectively. Standing and sitting body height were 164.1±8.9 and 88.3±4.3 cm, respectively. Height was significantly correlated with UL_CT, but this relation was not linear (r²=0.064 standing height, 0.062 sitting height). However, LL_CT showed a significant linear correlation with UL_CT (r²=0.485). UL_CT can be estimated indirectly by the following equation: UL_CT=0.823×LL_CT+8.093.

Conclusions

We could measure the ureteral length of healthy Koreans by UL_CT. UL_CT could be estimated indirectly by LL_CT and standing and sitting height. Of these variables, LL_CT provided the most accurate estimate of ureteral length.

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: 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.

Upper and Lower Tract Urothelial Imaging Using Computed Tomography Urography

Computed tomography (CT) urography is the best noninvasive method of evaluating the upper urinary tract for urothelial malignancies. However, the utility of CT urography is heavily contingent on the use of proper image acquisition protocols. This article focuses on the appropriate protocols for optimizing CT urography acquisitions, including contrast administration and the timing of imaging acquisitions, as well as the use of ancillary techniques to increase collecting system distention. In addition, imaging findings are discussed that should raise concern for urothelial carcinoma at each of the 3 segments of the urinary tract: the intrarenal collecting systems, ureters, and bladder.

Ectopic insertion of a duplicated ureter into prostatic urethra: Demonstration by 3D multi-detector computed tomography urography

Ectopic insertion of the ureter in the genitourinary tract is a rare congenital disorder, usually associated with ureteral duplication. Identification of the insertion open is critical for ureteric re-implantation. However, the challenge in the diagnosis of ectopic insertion of the ureter usually is to identify its insertion, particularly when the affected ureter is not dilated. Multi-detector computed tomography (MDCT) urography with nonionic iodinated contrast media delineates the ureteric course in the normal functioning kidney in the excretory phase [1]. This report presented a young male patient with ectopic insertion of a duplicated ureter diagnosed by MDCT urography. Three-dimensional (3D) analysis technology, such as volume rendering (with a color display improving the visualization of complex anatomy and 3D relationships) and maximum intensity projection (similar in principle to projection angiography), is useful for the illustration of urinary tract anatomy [1]. Rotated volume rendering reconstruction images and continual thinner maximum intensity projection reformatted images can be viewed as videos, which provides detail delineation of the ectopic ureteral insertion and its associated ureteral duplication.In this study, we reported MDCT urography and 3D analysis technology as an appropriate diagnostic method for the ectopic ureteral insertion and its associated complications.

Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET

Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction.

CT Urography for Evaluation of the Ureter

Over the past decade, computed tomographic (CT) urography has emerged as the primary imaging modality for evaluating the urinary tract in various clinical settings, including the initial workup of hematuria. With the widespread implementation of CT urography, it is critical for radiologists to understand normal ureteral anatomy and the varied appearance of pathologic ureteral conditions at CT urography. Pathologic findings at CT urography include congenital abnormalities, filling defects, dilatation, narrowing, and deviations in course. These abnormalities are reviewed, along with the indications for CT urography, current imaging protocols with specific techniques for optimal evaluation of the ureter, and dose reduction strategies.