This document discusses various imaging modalities for evaluating the urinary bladder and urethra, including plain films, cystography, retrograde urethrography, ultrasonography, CT, MRI, and radionuclide imaging. It then describes specific diseases that can affect the bladder and urethra, such as diverticula, infections, neurogenic disorders, tumors, and congenital anomalies. Magnetic resonance imaging and retrograde urethrography are often the best tests for staging bladder tumors and evaluating the urethra, respectively.
6. Various imaging modalities available for imaging of the
urinary bladder and urethra include the following:
Plain film
Cystography
Retrograde urethrography (RGU )
Voiding cystourethrography
(VCUG)
Ultrasonography (US)
Computed tomography (CT)
Magnetic resonance imaging (MRI)
Radionuclide imaging.
11. Ultrasonography
1. Bladder wall anatomy:
• Thickening of the wall and focal abnormalities
• Presence of trabeculation
• Diverticulae
2. Capacity of the bladder and postmicturation residual volume
3. Anatomy of bladder base and urethral opening
4. Distal ureteric anatomy
5. Intravesical filling defects and extraluminal masses causing bladder
compression
18. Bladder Diverticulae
Bladder diverticulae refer to pouch
like eversion or evagination of the
bladder wall.
may be congenital, but are more
commonly acquired
Congenital bladder diverticulae
develop as a result of herniation of
bladder mucosa through the detrusor
muscle, usually at a location slightly
above and lateral to the ureteric
orifice (Hutch diverticuli).
Diverticulae are sites of urinary stasis
and thus lead to infection.
19. Urachal Anomalies
In fetal life, the urachus connects the dome of the bladder to the
allantoic duct and develops from the superior portion of the
urogenital sinus. Normally, it obliterates before birth forming the
fibrous median umbilical ligament.
https://radiopaedia.org/cases/median-umbilical-ligament?lang=gb
22. Exstrophy
Exstrophy of the bladder is a
spectrum of defects in the
formation of the anterior
abdominal wall caused by
varying degrees of failure of
midline fusion of mesodermal
tissue below the umbilicus.
Classical exstrophy includes
epispadias, separation of pubic
bones (more than 10 mm) and
communication of bladder with
the anterior skin surface.
24. Hypospadias is the most
common congenital urethral
anomaly. It is sometimes
associated with other urogenital
abnormalities. The urethral
meatus is located on the ventral
surface
Complete caudal
duplication, the bladder is
usually completely divided
in the sagittal plane,
25. Neurogenic Bladder
Neurogenic bladder dysfunction
Spinal dysraphism, cord compression or
cord injury.
Cystography is very helpful in diagnosis of
neurogenic bladder.
Detrusor-external sphincter dyssynergia
(DSED),
Contraction of the external sphincter
occurs involuntarily at the same time as
detrusor contraction thus impeding urinary
flow and resulting in bladder outlet
obstruction.
“Christmas tree” or “pine tree” bladder.
26. Infections
Acute Cystitis
Acute cystitis due to bacterial infection is
most commonly the result of transurethral
infection and is common in females.
Escherichia coli - Most Common
Cystography is contraindicated in acute
infection.
Ultrasonography is the most useful modality
allowing evaluation of the upper tracts as
well as the bladder.
Emphysematous cystitis is almost always
seen in diabetic or immunocompromised
patients and E. coli is the most common
pathogen.
28. Chronic Cystitis
The hallmark of chronic cystitis is thickening, calcification and
irregularity of the bladder wall associated with trabeculation and
often diminished bladder capacity.
29. Cystitis Cystica
Cystitis cystica is a benign condition commonly seen in women
with recurrent or chronic cystitis, or in chronically irritated
bladders, such as those catheterized for long periods or with
calculus disease of the bladder. Multiple round contour defects
at the bladder base can be seen in cystitis cystica and
malakoplakia, on cystogram and US.
30. Malakoplakia
Malakoplakia is an uncommon granulomatous response to an infection of
the urinary tract, predominantly with E. coli. defects especially in the
trigone and bladder base. Accompanying bladder wall thickening may
also be seen, simulating carcinoma.
31. Schistosomiasis
Caused by Schistosoma
hematobium. Producing
polypoidal bladder wall
thickening, which is nonspecific in
appearance. In late stages
fibrosis leads to a small capacity
bladder with focal or curvilinear
dense wall calcification.
Extravesical Processes
Appendicitis, diverticulitis and
pelvic abscesses may produce
reactive thickening of the bladder
wall and mucosal irregularities.
32. Bladder Tumors
Imaging of bladder transitional cell carcinomas has a number of roles:
• Incidental discovery of the tumour
• Tumour staging
• Tumour staging of locally advanced masses
• Evaluation of distant metastases and nodal status
• Surveillance
33.
34. Ultrasound
Ultrasound has a limited role to play in either diagnosis or staging
transitional cell carcinomas of the urinary tract in general.
CT
Bladder transitional cell carcinomas appear as either focal regions of
thickening of the bladder wall, or as masses protruding into the bladder
lumen or extending into adjacent tissues.
Asymmetric mural thickening should be viewed with suspicion.
The masses are of soft tissue attenuation and may be encrusted with
small calcifications.
Nodal metastases are common
35. Computed tomography plays a major role in staging of
carcinoma of the bladder rather than detection of the primary
neoplasm.
36. CT or conventional urography
Role is in the assessment of the remainder of the urinary tract.
MRI
MRI is superior to other modalities in locally staging the tumour and is in some
instances able to distinguish T1 from T2 tumours on T2 weighted images.
• T1: isointense compared to muscle
lightly hyperintense compared to muscle
◦ Discontinuity when muscle wall invasion
• T1 C+ (Gd): shows enhancement
PET -unsuitable
37. Magnetic resonance imaging is the most accurate staging
technique in invasive tumors. T2-weighted or contrast enhanced
T1-weighted sequences are needed to evaluate the infiltrating
component of the tumor.
38.
39. SPECIFIC DISEASES OF URETHRA
Neisseria gonorrhea is associated with the gonococcal urethritis.
Common organism of nongonococcal urethritis is Chlamydia
trachomatis.
Purulent urethral discharge is the most common presentation of patients
with urethritis.
Urethritis
40. The urethral stricture in typical gonococcal urethritis is seen as an
irregular several centimeters long narrowing of urethra in
urethrography.
The causative factors of scar formation in this region are poor
flushing by urination and the predominance of Littré glands in this
area. Urethrography may show associated Littré glands dilatation.
41. • Periurethral abscess arises initially when a Littré gland becomes
obstructed by inspissated pus or fibrosis .
• Periurethral abscess is a life threatening infection of the male
urethra and periurethral tissue and frequently a sequelae of
gonococcal infection, urethral stricture disease, or urethral
catheterization.
42. Urethroperineal fistulas most often occur as a sequel of periurethral
abscess. Narrow fistulous tract is formed from the urethra to the
perineum and subsequently urination occurs through the perineal
fistulas, resulting in the so-called “watering can perineum”.2
Urethroperineal fistulas are usually the result of tuberculosis and
schistosomiasis infections.
43. Condyloma Acuminata (Venereal Warts)
Condyloma acuminata are caused by viral infection resulting in soft,
sessile, squamous papillomas on the penile glans and shaft and the
prepuce.
Warts may extend to the prostatic urethra and bladder. The diagnostic
procedure of choice is VCUG.
44. Tuberculosis
Genital tuberculosis is usually a
descending infection from upper
urinary tract. Up to 70% of patients
show associated prostatic
involvement.
Urethral discharge and associated
involvement of the epididymis,
prostate and other parts of the
urinary system is seen in acute
phase.
Numerous fistulas develop in
perineal and scrotal region in
tuberculous urethral strictures which
result in watering-can perineum.
45. Urethral Diverticulum
Acquired diverticulae more common.
Commonly occur in the females. It
occurs most commonly in the mid
urethra and on the posterolateral wall
rather than on the anterior wall.
Inflammation or repeated minor
trauma to skene (periurethral) glands
can result in dilation followed by
rupture and diverticulae formation.
Associations include—ductal
remnant (Wolffian/Mullerian);cloacal
epithelium
The diagnosis is usually made with
VCUG (accuracy of 65%) or cross-
sectional imaging.
46. Urethral Calculi
Most urethral calculi are secondary due to expulsion from the bladder
during voiding (migrant calculi).
Rarely when there is stasis like within a diverticulum or proximal to a
stricture, primary stone formation occurs.
47. Tumors of the Urethra
Multiple radiographic investigations are useful,
including retrograde cystourethrography,
voiding cystourethrogram, contrast-enhanced
CT, and MRI.
MRI
MRI is most sensitive and specific for local
extension.
◦ low signal mass
◦ difficult to differentiate from urethra
◦ high signal mass
• T1 C+ (Gd)
◦ variable enhancement
48. Metastatic Tumors of
Urethra
Rare.
Local seeding - appear as
multifocal small mucosal
nodules during urethrography.
Local spread of prostatic,
rectal, testicular or spermatic
cord malignancy- involve the
corpus spongiosum, causing
marked urethral narrowing
and irregularity
The urinary bladder is a musculomembranous sac - reservoir for the urine; The empty bladder flattened tetrahedron and when distended with fluid it becomes round or oval in shape.
In adults between 500 and 600 mL.
The normal wall of the bladder is smooth and should be regular and uniform in thickness (typically 2–3 mm in fully distended bladder) not exceeding 6 mm in adults.
and its size, position and relations vary according to the amount of fluid it contains.
Anterior urethra
penile (spongy, pendulous) urethra (~16 cm long): encased by corpus spongiosum of the penis
the longest portion
the 'fossa navicularis' is a small normal dilatation of the distal penile urethra
bulbar (bulbous) urethra: traverses the root of the penis
it receives the ducts from the bulbourethral glands and the glands of Littré
lined by pseudostratified columnar epithelium.
Posterior urethra
membranous urethra (1 cm long): passes through the urogenital diaphragm, surrounded by sphincter urethrae
the shortest and narrowest portion
prostatic urethra (3 cm long): surrounded by the prostate gland; on its posterior wall runs the urethral crest and the prominent smooth muscle verumontanum
lined by transitional columnar epithelium.
The female urethra measures approximately 4 cm in length. It is embedded in the anterior vaginal wall and runs with the vagina through the urogenital hiatus.
The female urethra begins at the internal urethral meatus at the bladder neck and opens in the vestibule of the vagina, 2.5 cm below the clitoris. Paraurethral (Skene) glands line the urethra at the external urethral meatus.
etection of radiopaque calculi or foreign bodies, calcification, abnormal gas pattern and in identification of soft tissue and the bony abnormalities
detection of radiopaque calculi or foreign bodies, calcification, abnormal gas pattern and in identification of soft tissue and the bony abnormalities.
Radiolucent foreign bodies can be seen if these get encrusted with calcium.
Causes of bladder wall calcification include tuberculosis, tumors, radiation cystitis, cyclophosphamide induced cystitis, alkaline incrustation cystitis, amyloidosis and schistosomiasis.
Bladder neoplasms may be suggested on detection of stippled calcification.
In emphysematous cystitis, the plain film typically shows gas within the bladder lumen and irregular streaky radiolucencies within the bladder wall. The presence of gas within the ureter may be seen in the setting of emphysematous pyeloureteritis or emphy-sematous pyelonephritis. Plain films may occasionally be helpful for the detection of metastases, spinal abnormalities in cases of neurogenic bladder and diastasis of the pubic symphysis in patients with exstrophy/ epispadias anomaly.
Contrast cystogram can distinctly demonstrate intraluminal calculi, hematomas, tumors (Fig. 2) and wall irregularities. In traumatic injury of the bladder, cystogram depicts the type of bladder rupture (extraperitoneal or intraperitoneal), in addition to detection of pelvic fractures
Retrograde urethrography is indicated in the evaluation of urethral injuries, strictures and fistulas and is considered to be the best initial modality for urethral and periurethral imaging in men.
Voiding Cystourethrography (VCUG)
Voiding cystourethrography is the most commonly used method in the evaluation of the posterior male urethra and female urethra. Voiding urethrography is done after filling bladder with contrast material using transurethral or suprapubic catheter.
Sonourethrogram showing a stricture (arrows) of penile urethra
Contrast-enhanced CT with delayed imaging or retrograde bladder filling (CT cystography) has been shown to be highly accurate and equivalent to conventional cystography in the detection of bladder rupture.5
Magnetic resonance: Coronal T2 image of urinary bladder. Note low signal intensity of detrusor muscle
advantages being simplicity, lower radiation dose and no catheterization needed.
On cystogram, bladder diverticulae are seen as outpouchings from the bladder which may show persistence of contrast in the postmicturition phase. On US these appear as well-defined, thin-walled fluid containing structures communicating with the bladder lumen. The most important use of US is to detect the complications, i.e. stone or tumor in the diverticulum, which is not always possible to assess on cystography or endoscopy.
Diverticulae are sites of urinary stasis and thus lead to infection.
It lies in space of Retzius behind the abdominal wall and anterior to the peritoneum
patent urachus is diagnosed when there is leakage of urine from the umbilicus. Retrograde injection of contrast into umbilical orifice can directly demonstrate patent urachus. It may also fill up during voiding cystourethrogram, best demonstrated in the lateral projection
Urachal cyst is not delineated on conventional urography studies.
An urachal diverticulum is identified as urine filled anterosuperior protrusion of the bladder dome on cystography.
In adults the urachal diverticulum may be complicated with infection or malignancy (Figs 7 and 8).
Sagittal gadolinium-enhanced T1-weightedfat-suppressed MR images demonstrate a fluid-filled collection (arrows)
Urachal anomalies can be delineated on US, CT and MRI. Ultrasonography reveals a tubular, anechoic structure in the lower, mid anterior abdominal wall. Magnetic resonance imaging is very helpful as it permits multiplanar imaging especially in the sagittal plane.
Penile hypospadias with meatal stenosis
Urethral duplication can be divided into the following types blind and incomplete to complete caudal duplication. [6] In complete caudal duplication, the bladder is usually completely divided in the sagittal plane,
Pubic diastasis and developmental dysplasia involving the right hip joint. A VCUG image (B) shows complete duplication of the bladder (*) and urethra (arrows)
This can be associated with anomalies of the gastrointestinal tract, genital system and lower spine. Anatomy of duplication can be well-demonstrated on US and MRI.
On VCUG, there may or may not be vesicoureteral reflux. In detrusor areflexia VCUG often reveals a smooth, thin-walled bladder with increased capacity, occasionally up to several liters and extending high into the abdomen. Significant postvoid residue is seen in both these conditions.
On US, cystitis show thickened and less distinct bladder wall with internal echoes or debris. Cobblestone appearance of bladder wall can be seen in severe bladder edema due to acute cystitis
Emphysematous cystitis: Sagittal reformatted CT image showing air pockets (arrows) within the bladder wall
Submucosal granulomas containing macrophages with inclusion bodies known as ‘Michaelis–Gutmann bodies’ are characteristic. It may affect any part of the urinary tract.
Radiographically, these are seen as single or multiple mural filling
Primary bladder tumors are mostly epithelial in origin, less than 10% arising from a nonepithelial source.
All epithelial tumors are malignant, majority being transitional cell type with SCC and adenocarcinoma being relatively uncommon.
Nonepithelial tumors may be benign (e.g. leiomyoma, fibroma) or malignant (e.g. leiomyosarcoma and rhabdomyosarcoma).
Various other primary tumors or masses may occur, including pheochromocytoma, hemangioma, leukoplakia, lymphoma and endometriosis. The bladder can also rarely be the site of metastases.
Transitional cell carcinoma (TCC) of bladder: Intravenous urograms image showing large polypoidal filling defects (arrows) within the bladder
Transitional cell carcinoma of bladder: Ultrasonography image showing intraluminal polypoidal mass within the bladder with invasion of left ureter (arrow)
However, CT is not accurate for the early stages and its reliability increases with more advanced disease (Fig. 13). Computed tomography has limited value in early disease as it cannot differentiate between the various layers of the bladder wall and cannot therefore distinguish lesions limited
ransitional cell carcinoma of bladder: Computed tomography axial image showing a large polypoidal growth (arrow) along right lateral wall and base of bladder causing ureteric obstruction. A small tumor is also seen along left lateral wall (ar
The clinical staging (with deep fractioned transurethral resection) is much less accurate in staging invasive (Stages T2–T4) tumors.
Cystogram cannot detect an early growth, extent of extravesical spread or status of the adjacent organs .
Although the intravesical position of many tumors can be visualized on US, an accurate assessment of the depth of penetration of the bladder wall cannot be done with US.
The diagnostic accuracy of the transabdominal US for depth of infiltration ranges from 55 to 95%. Perivesical invasion cannot be frequently determined, however, extravesical spread may be recognized by the asymmetry due to infiltration.
Tumors involving the posterior bladder wall and neck; prostate and seminal vesicles may be visualized better with transrectal approach. Finally, none of the ultrasound methods optimally assesses the regional nodal status.
Transitional cell carcinoma of bladder: Axial T2-weighted image of a papillary transitional cell carcinoma shows a intraluminal mass which is intermediate in signal intensity. The pedicle is clearly seen (arrow). The muscle wall is not infiltrated. Perivesical enlarged vessels are noted adjacent to the tumor on left side
Visualization of the low signal intensity line on T2-weighted images representing the uninvolved bladder wall between the tumor and perivesical fat is an important feature in MRI staging
Ta: non-invasive papillary tumour
Tis: in situ (non-invasive flat)
T1: through lamina propria into sub-epithelial connective tissues
T2: into muscularis propria
T2a: only invades inner half of the muscle
T2b: invades into outer half of the muscle
T3: invasion into perivesical tissues
T3a: microscopic extravesical invasion
T3b: macroscopic extravesical invasion
T4: direct invasion into adjacent structures
T4a: prostate, uterus, vaginal vault
T4b: pelvic side wall and/or abdominal wall
Narrow, elongated, asymmetric, irregular, or absent opacification of normal cone shaped proximal membranous urethra means involvement of the membranous urethra by stricture (seen in more than 90% of cases).20
However, the diagnosis is often not suspected until RGU has been performed. Typically multiple papillary filling defects are seen in the anterior urethra.
Fig. 22:Rectourethral fistula in a young male who had tuberculous prostatic abscesses and presented with pneumaturia: Transrectal US image shows the echogenic fistulous tract (arrows) between the rectum (star) and the prostatic urethra
Retrograde urethrography typically demonstrates an anterior urethral stricture and associated multiple prostatocutaneous and urethrocutaneous fistulas. Similantaneous fistulography may be useful for assessing the entire urethra.
The differential diagnosis includes vaginal cyst (Gartner duct, paramesonephric or müllerian duct cyst, epithelial inclusion cyst), ectopic ureterocele, endometrioma and urethral tumors.26
Urethral diverticula may be complicated by infection, stone formation and malignant degeneration. The most common malignancy arising from diverticulae being adenocarcinoma.
The common MR finding is a mass with relatively decreased signal compared to the normal corporal tissue in both T1- and T2-weighted sequences. Magnetic resonance
imaging can depict invasion of the corpora cavernosa and is used for determining exact tumor site, size and local invasion
