Multimodality Imaging in Ureteric and Periureteric Pathologic Abnormalities

Imaging of ureter: a primer for the emergency radiologist

In this review article, we will discuss the gamut of abnormalities involving the ureters. In the emergency department, ureterolithiasis is the most common indication for imaging abdomen and pelvis. However, spectrum of ureteral abnormalities including congenital, infectious and inflammatory, primary and secondary ureteral malignancies, retroperitoneal fibrosis rare described in this article may be encountered. Thus, we will describe acute subacute as well as chronic conditions that may affect ureter. Knowledge of common, as well as rare entities and their imaging features, is of utmost importance to enable appropriate management.

CT and MRI in Urinary Tract Infections: A Spectrum of Different Imaging Findings

There are many acute and chronic infections affecting the urinary tract including bacterial, fungal and viral infections. Urinary tract infections (UTIs) can present in many different patterns with variable degrees of severity varying from asymptomatic and uncomplicated forms to life threatening complicated infections. Cross-sectional imaging techniques—including both computed tomography (CT) and magnetic resonance imaging (MRI)—have become very important tools not only for evaluation of UTIs, but also for detection of associated complications. Selection of either CT or MRI in the UTI evaluation depends on several factors such as the presence of contraindication, experience, cost and availability. CT and MRI help in early detection and management of UTIs that reduce the prevalence and severity of complications. In this article we will present the radiologic findings at CT and MRI in different types of upper and lower UTIs including acute pyelonephritis, intrarenal and perinephric abscesses, pyonephrosis, chronic pyelonephritis, emphysematous UTIs, xanthogranulomatous pyelonephritis, tuberculosis (TB), bilharziasis, fungal infection, corynebacterium infection, ureteritis, cystitis, prostatitis, prostatic abscess and urethritis.

CT Urography Findings of Upper Urinary Tract Carcinoma and Its Mimickers: A Pictorial Review

Urothelial carcinoma (UC) is the fourth most frequent tumor in Western countries and upper tract urothelial carcinoma (UTUC), affecting pyelocaliceal cavities and ureter, accounts for 5-10% of all UCs. Computed tomography urography (CTU) is now considered the imaging modality of choice for diagnosis and staging of UTUC, guiding disease management. Although its specificity is very high, both benign and malignant diseases could mimic UTUCs and therefore have to be well-known to avoid misdiagnosis. We describe CTU findings of upper urinary tract carcinoma, features that influence disease management, and possible differential diagnosis.

Differentiation of Upper Urinary Tract Lesions Using MDCT: Benign Vs Malignant

RATIONALE AND OBJECTIVES

To evaluate the accuracy of multiple detector computed tomography (MDCT) in differentiating benign and malignant lesions of upper urinary tract (UUT).

MATERIALS AND METHODS

Fifty-four patients with 55 suspected UUT lesions were included in the study. All patients underwent MDCT scan with nephrographic and excretory phases. The unenhanced phase was also performed in 38 cases. The final diagnosis was made by histology in 48 lesions: 43-after surgery, 5-after biopsy and by MDCT follow-up over at least 15 months in the remaining 7 lesions. The following CT features were evaluated: number of lesions, lesion appearance (mass or wall thickening), presence of calcifications, internal border appearance (smooth or irregular), and size and enhancement (presence or absence). The relationship between imaging characteristics and pathology (benign vs malignant) was assessed with logistic regression, univariable diagnostic accuracy, and with classification and regression tree analysis.

RESULTS

Patients with mass morphology had a significantly higher probability of malignancy (odds ratio [OR]: 3.73, 95%CI: 1.02-13.72, p = 0.047) compared to patients with thickened wall morphology. The presence of an irregular internal border was also significantly associated with malignancy (OR: 12.14, 95%CI: 2.95-50.06, p < 0.001). No significant associations were found between malignancy and lesion size (p = 0.29), calcifications (p = 0.93) or enhancement (p = 0.68).

CONCLUSION

Mass morphology and irregular internal border are reliable signs to suggest malignancy in UUT lesions.

Update on MR urography (MRU): technique and clinical applications

Magnetic resonance imaging of the upper tract (pyelocalyces and ureters) or MR Urography (MRU) is technically possible and when performed correctly offers similar visualization of the upper tracts and for detection of non-calculous diseases of the collecting system similar specificity but with lower sensitivity compared to CTU. MRU provides the ability to simultaneously image the kidneys and urinary bladder with improved soft tissue resolution, better tissue characterization and when combined with assessment of the upper tract, a comprehensive examination of the urinary system. MRU requires meticulous attention to technical details and is a longer more demanding examination compared to CTU. Advances in MR imaging techniques including: parallel imaging, free-breathing motion compensation techniques and compressed sensing can dramatically shorten examination times and improve image quality and patient tolerance for the exam. This review article discusses updates in the MRU technique, summarizes clinical indications and opportunities for MRU in clinical practice and reviews advantages and disadvantages of MRU compared to CTU.

Tumors of Renal Collecting Systems, Renal Pelvis, and Ureters: Role of MR Imaging and MR Urography Versus Computed Tomography Urography

Hematuria evaluation remains a common problem, particularly in patients who smoke and are at risk for urothelial tumors. Lifetime surveillance of the urothelium is often required once urothelial cancer is diagnosed. Computed tomography urography (CTU) has exquisite sensitivity and specificity for identification of renal and urothelial lesions. The examination is well accepted by patients and physicians. Possible harms include radiation exposure and contrast-induced nephropathy. MR imaging is also an accurate test, but requires longer exam times, and may not demonstrate stones. We present the technical and interpretation skills required to use MR urography and CTU effectively.

Infectious and Inflammatory Diseases of the Urinary Tract: Role of MR Imaging

Urinary tract infection (UTI) is among the most common of bacterial infections. Imaging studies are only required in cases of complicated UTIs. Ultrasound remains the first-line imaging method; however, CT is the gold standard for evaluation of UTIs. MR imaging's improved contrast resolution and absence of ionizing radiation may recommend its use for assessment of lower UTIs. Furthermore, MR imaging performs with diagnostic accuracy at least similar to CT in complicated UTIs, except for the identification of calculi and emphysematous pyelonephritis. In this article, the role of MR imaging for the evaluation of infectious and inflammatory disease processes of the urinary tract is reviewed.

Cross-sectional imaging of complicated urinary infections affecting the lower tract and male genital organs

Complicated urinary tract infections (C-UTIs) are those associated with structural or functional genitourinary abnormalities or with conditions that impair the host defence mechanisms, leading to an increased risk of acquiring infection or failing therapy. C-UTIs occur in patients with risk factors such as neurogenic dysfunction, bladder outlet obstruction, obstructive uropathy, bladder catheterisation, urologic instrumentation or indwelling stent, urinary tract post-surgical modifications, chemotherapy- or radiation-induced damage, renal impairment, diabetes and immunodeficiency.

Multidetector CT and MRI allow comprehensive investigation of C-UTIs and systemic infection from an unknown source. Based upon personal experience at a tertiary care hospital focused on the treatment of infectious illnesses, this pictorial essay reviews with examples the clinical features and cross-sectional imaging findings of C-UTIs affecting the lower urinary tract and male genital organs. The disorders presented include acute infectious cystitis, bladder mural abscesses, infections of the prostate and seminal vesicles, acute urethritis and related perineal abscesses, funiculitis, epididymo-orchitis and scrotal abscesses. Emphasis is placed on the possible differential diagnoses of lower C-UTIs.

The aim is to provide radiologists greater familiarity with these potentially severe disorders which frequently require intensive in-hospital antibiotic therapy, percutaneous drainage or surgery.

Teaching Points

• Complicated urinary tract infections occur in patients with structural or functional risk factors.

• CT and MRI comprehensively investigate complicated urinary infections and sepsis from unknown sources.

• Infections of the urinary bladder, prostate, seminal vesicles, urethra and scrotum are presented.

• Emphasis is placed on differential diagnoses of complicated lower urogenital infections.

• Unsuspected urinary infections may be detected on CT performed for other clinical reasons.

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.

Ureteral Dilatation with No Apparent Cause on Intravenous Urography: Normal or Abnormal? A Pilot Study

A pilot study was done in 18 adults to assess the significance of ureteral dilatation having no apparent cause seen on Intravenous Urography (IVU). A clinicoradiological evaluation was undertaken to evaluate the cause of ureteral dilatation, including laboratory investigations and sonography of the genitourinary tract. This was followed, if required, by CT Urography (using a modified technique). In 9 out of 18 cases, the cause of ureteral dilatation on laboratory investigations was urinary tract infection (6) and tuberculosis (3). In the remaining 9 cases, CTU identified the cause as extrinsic compression by a vessel (3), extrinsic vascular compression of the ureter along with ureteritis (2), extrinsic vascular impression on the right ureter and ureteritis in the left ureter (1), ureteral stricture (2), and ureteral calculus (1). Extrinsic vascular compression and strictures did not appear to be clinically significant in our study. Hence, ureteral dilatation without any apparent cause on intravenous urogram was found to be clinically significant in 12 out of 18 (66.6%) cases. We conclude that ureteral dilatation with no apparent cause on IVU may indicate urinary tract tuberculosis, urinary tract infection (E. coli), or a missed calculus. Thus, cases with a dilated ureter on IVU, having no obvious cause, should undergo a detailed clinicoradiological evaluation and CTU should be used judiciously.

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.

Renal and urologic disorders in antiretroviral-treated patients with HIV infection or AIDS: spectrum of cross-sectional imaging findings

In the aging human immunodeficiency virus (HIV)-infected population with improved immune function under antiretroviral treatment, many different opportunistic disorders may be encountered, along with rare presentations or complicated forms of common diseases. Renal and urologic abnormalities observed in the setting of HIV infection or acquired immunodeficiency syndrome are reviewed with their imaging appearances, including renal dysfunction, urolithiasis, urinary tract infections and related complications, genitourinary tuberculosis, vascular lesions, urogenital tumors, and bladder abnormalities, with emphasis on characterization. In HIV-positive patients, early cross-sectional imaging is warranted to detect uncommon disorders and complications, with the aim to preserve renal function.