Radiology of the Urinary Tract

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Questions and Answers

What is the primary use of ultrasound in investigating patients with symptoms thought to arise from the urinary tract?

To assess the bladder and prostate

To diagnose hydronephrosis, renal tumours, abscesses and cysts

To measure the post-micturition residual volume of urine

To investigate patients with symptoms thought to arise from the urinary tract (correct)

What is the normal length of an adult kidney measured by ultrasound?

9-12 cm (correct)

10-13 cm

11-14 cm

7-10 cm

What is the term used to describe the imaging of the renal tract using intravenous iodinated contrast medium?

Urography (correct)

Ultrasonography

CT scan

Radionuclide examinations

What is the purpose of assessing the bladder in the distended state?

To assess the bladder wall definition Signup and view all the answers

What is the term used to describe the central echo-dense region of the kidney?

Central echo complex Signup and view all the answers

What is the purpose of assessing renal length in children with urinary tract infections?

To assess and follow-up renal size and scarring Signup and view all the answers

What is the normal difference in length between the two kidneys?

Less than 1.5 cm Signup and view all the answers

What is the name of the two types of urography?

The traditional intravenous urogram and CT urography Signup and view all the answers

What is the normal appearance of the bladder on imaging?

Smooth outline Signup and view all the answers

What is the purpose of the initial noncontrast CT in CT urography?

To identify calcification Signup and view all the answers

What is the advantage of MRI over CT in renal tract imaging?

Ability to obtain scans directly in multiple planes Signup and view all the answers

What is the main disadvantage of MRI in renal tract imaging?

Inability to visualize calcification Signup and view all the answers

What is the purpose of the renogram (DTPA) scan?

To assess kidney filtration and perfusion Signup and view all the answers

What is the purpose of the voiding cystography exam?

To detect urinary reflux and bladder dysfunction Signup and view all the answers

What is the best phase to demonstrate corticomedullary differentiation on MRI?

T1-weighted images with intravenous contrast enhancement Signup and view all the answers

What is the purpose of the DMSA scan?

To provide detailed images of kidney structure and identify scarring Signup and view all the answers

What is the main advantage of CT over traditional IVU?

It is more sensitive for the detection of stones Signup and view all the answers

What is the purpose of the non-contrast CT in the renal tract?

To identify all renal tract calcifications Signup and view all the answers

What is one of the indications for performing a urethral examination?

To demonstrate extravasation from the urethra or bladder neck following trauma Signup and view all the answers

What is the 'CT KUB'?

A non-contrast CT scan used to identify renal tract calcifications Signup and view all the answers

What is the purpose of renal arteriography?

To confirm CT or MRI findings of vascular anatomy prior to renal surgery Signup and view all the answers

What is the main indication for an IVU study?

To identify renal calculi Signup and view all the answers

What percentage of stones are radiolucent?

10-20% Signup and view all the answers

What is the purpose of the plain film in an IVU study?

To identify all calcifications Signup and view all the answers

What is the most common type of renal parenchymal mass in adults?

Renal cell carcinoma Signup and view all the answers

What is the normal shape of a calix in a normal IVU study?

Cupped Signup and view all the answers

What is the most common type of renal parenchymal mass in children?

Wilm's tumor Signup and view all the answers

What is the shape of the normal renal pelvis and pelvi-ureteric junction in an IVU study?

Funnel-shaped Signup and view all the answers

What type of stones are radiolucent?

Xanthine and uric acid stones Signup and view all the answers

Why are the ureters usually seen in only part of their length on any one film of IVU?

Due to obliteration of the lumen by peristalsis Signup and view all the answers

Which type of MRI image is best suited for visualizing the renal collecting systems, ureters, and bladder?

T2-weighted images Signup and view all the answers

What is a normal variant that may be demonstrated on MRI as a mass-like structure?

Column of Bertin Signup and view all the answers

What is the primary purpose of retrograde and antegrade pyelography?

To confirm a diagnosis when less invasive means are unsuccessful Signup and view all the answers

What is the primary indication for voiding cystourethrography?

To diagnose vesicoureteric reflux Signup and view all the answers

What is the purpose of videourodynamic examination?

To combine voiding cystourethrography with bladder pressure measurements Signup and view all the answers

In which patients is videourodynamic examination indicated?

All of the above Signup and view all the answers

What is the purpose of an ascending urethrogram?

To fully visualize the male urethra Signup and view all the answers

What is the term for demonstrating the pelvicaliceal system and ureters?

Pyelography Signup and view all the answers

Study Notes

Radiological Examinations of the Urinary Tract

The radiological examinations of the urinary tract are: • Ultrasound • Intravenous urography (IVU) • Computed tomography (CT) • Radionuclide examinations • Magnetic resonance imaging (MRI) • Arteriography • Studies requiring catheterization or direct puncture of the collecting systems

Imaging Technique: Ultrasound

The main uses of ultrasound are: • To investigate patients with symptoms thought to arise from the urinary tract • To demonstrate the size of the kidneys and exclude hydronephrosis in patients with renal failure • To diagnose hydronephrosis, renal tumors, abscesses, and cysts, including polycystic disease • To assess and follow-up renal size and scarring in children with urinary tract infections • To assess the bladder and prostate
Normal renal ultrasound: • The kidneys should be smooth in outline • The parenchyma surrounds a central echo-dense region, known as the central echo complex • The normal adult renal length, measured by ultrasound, is 9-12 cm • Renal length varies with age, being maximal in the young adult • Normal ureters are not usually visualized due to overlying bowel gas • The urinary bladder should be examined in the distended state, with sharply defined and barely perceptible walls

Urography

Urography is the term used to describe the imaging of the renal tract using intravenous iodinated contrast medium
There are two types of urography: • The traditional intravenous urogram (IVU) • CT urography
The principles of both techniques are similar: • Firstly, 'non-contrast' imaging of the renal tract is required to identify all renal tract calcifications • In some cases, where the clinical question relates to renal calculi, the non-contrast CT may be sufficient (known as the 'CT KUB')
The main indications for urography are: • To investigate patients with symptoms thought to arise from the urinary tract • To demonstrate the size of the kidneys and exclude hydronephrosis in patients with renal failure

IVU Study

Plain film in intravenous urogram: • Used to identify all calcifications • Decide if they are in the kidneys by relating them to the renal outlines • Calcification seen in the line of the ureters or bladder must be reviewed with post-contrast scans to determine whether the calcification lies in the renal tract
Films taken after injection of contrast medium: • Kidneys:
- Check that the kidneys are in their normal positions
- Identify the whole of both renal outlines
- Measure the renal lengths • Calices:
- The calices should be evenly distributed and reasonably symmetrical
- The shape of a normal calix is 'cupped' and when it is dilated it is described as 'clubbed' • Pelvis and ureters:
- The normal renal pelvis and pelvi-ureteric junction are funnel-shaped
- The ureters are usually seen in only part of their length on any one film of IVU • Bladder:
- The bladder is a centrally located structure that should have a smooth outline
- It often shows normal smooth indentations from above owing to the uterus or the sigmoid colon, and from below by muscles of the pelvic floor

Computed Tomography Urography

CT is initially performed without intravenous contrast medium (non-contrast CT or 'CT KUB') to identify calcification
Indications and include: • The early renal cortical enhancement phase • The homogeneous nephrogram phase • The delayed urographic phase, obtained several minutes later to demonstrate contrast within the collecting systems

Magnetic Resonance Imaging

Magnetic resonance imaging gives similar anatomical information to CT, with the advantage of being able to obtain scans directly in multiple planes
It is generally used in selected circumstances, including: • To demonstrate renal artery stenosis • Inferior vena caval extension of renal tumors • To clarify problems not solved by ultrasound or CT • To assess the extent of bladder or prostate cancer prior to consideration for surgery
Normal magnetic resonance imaging: • The renal contours should be smooth • Corticomedullary differentiation is best seen on T1-weighted images • The renal collecting systems, ureters, and bladder are best seen on T2-weighted images, as the fluid returns a high signal intensity

Special Techniques

Retrograde and antegrade pyelography: • The techniques of retrograde and antegrade pyelography involve direct injection of contrast material into the pelvicaliceal system or ureters through catheters placed via cystoscopy or percutaneously into the kidney via the loin • The indications are limited to those situations where the information cannot be achieved by less invasive means
Voiding cystourethrography (micturating cystogram) and videouro dynamics: • In voiding cystourethrography, the bladder is filled with iodinated contrast medium through a catheter and films are taken during voiding • The entire process is observed fluoroscopically to identify vesicoureteric reflux • Videourodynamic examination combines voiding cystourethrography with bladder pressure measurements • It is indicated in the investigation of patients with incontinence, obstructive symptoms, and neurogenic bladder
Urethrography: • The urethra is visualized during voiding cystourethrography • For full visualization of the male urethra, an ascending urethrogram with contrast medium injection via the external urethral meatus is necessary • The usual indications for the examination are to identify urethral strictures and to demonstrate extravasation from the urethra or bladder neck following trauma

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Description

This quiz covers the different radiological examinations used to diagnose and evaluate urinary tract disorders, including ultrasound, intravenous urography, and magnetic resonance imaging.