Genitourinary Radiology
Jerry Glowniak, MD
Department of Radiology
Detroit Receiving Hospital
Detroit Medical Center/Wayne State
University
Radiological Anatomy:
Kidneys and adjacent spaces
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The radiological anatomy of the kidneys
consists of the cortex, medulla (renal
pyramids), renal sinus, and the
collecting system.
The kidneys and their adjacent spaces
lie in the retroperitoneum in the
abdomen and pelvis.
Retroperitoneal Spaces
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Radiologically, the retroperitoneum in the
abdomen is divided into the perinephric
spaces, and the anterior and posterior
pararenal spaces.
The retroperitoneal (extraperitoneal)
spaces in the pelvis are more complex.
The abdominal pararenal spaces continue
into the pelvis The perinephric spaces are
confined to the abdomen.
The Perinephric Spaces
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The largest retroperitoneal spaces.
Contents: the kidneys, adrenal glands,
proximal ureters, and perirenal fat. The
right and left spaces communicate
inferiorly.
Delimited by the renal fascia which has a
well-defined anterior component (Gerota’s
fascia, anterior renal fascia) and thinner
posterior component (Zuckerkandl’s
fascia, posterior renal fascia).
Retroperitoneal Spaces:
Abdomen
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AC – Ascending
Colon
DC –
Descending
Colon
D – Duodenum
K – Kidney
A – Aorta
V – Vena Cava
Anterior Pararenal Space
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Single space anterior to the perinephric
spaces.
Contents: Pancreas, second and third
portions of the duodenum, aorta, inferior
vena cava, ascending and descending
colon
Anterior boundary: posterior parietal
peritoneum.
Posterior boundary: Anterior renal fascia
Posterior Pararenal Spaces
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Right and left spaces posterior and
lateral to the perinephric spaces.
Contents: Fat
Anterior boundary: posterior renal
fascia and lateroconal ligament
Posterior boundary: Transversalis fascia
Anterior to the colon, it is continuous
with the properitoneal fat.
Retroperitoneal Spaces:
Detailed View
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DC –
Descendin
g Colon
K – Kidney
PM –
Psoas
Muscle
Imaging Modalities
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Intravenous pyelogram
Computed Tomography (CT)
Ultrasound
Nuclear Medicine
Magnetic Resonance Imaging (MRI)
Plain Film
Intravenous Pyelogram
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Gold Standard 20 years ago
Becoming an obsolete technique
Limited views of kidneys
Two dimensional technique
Largely replaced by CT
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Normal excretory
phase of an IVU
(intravenous
urogram), 10
minute image.
Kidneys are
excreting contrast
into non dilated
calyces (arrows),
renal pelvis (p),
ureters (*) and
bladder (B).
Computed Tomography
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Imaging modality of choice for most
abnormalities.
Advantages: Fast, widely available, high
resolution.
Disadvantages: Radiation, intravenous
contrast, less specific than MRI
CECT kidneys, 60 sec
(nephrogram phase) ,
would show renal
parenchymal lesions well
CECT kidneys; 4 min
( pyelogram phase), showing
excretion of contrast into
collecting system,
would show urothelial lesions
well, such as TCC , stones,
blood clots
1
2
3
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CECT scan of abdomen with
(1) axial, (2) coronal, and (3)
sagittal 3D reconstructions
shows multiple cysts (c) of
varying sizes in the right
kidney in a pattern most
consistent with multicystic
dysplastic kidney disease.
3D reconstructed
image from CT
scan of the
abdomen and
pelvis, a CT
“IVP”,
shows RK (K), a
normal ureter
(arrows), and the
ureter's insertion
into the bladder.
Ultrasound
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Useful in a wide variety of genitourinary tract
abnormalities.
Advantages: Highest resolution, non-invasive,
widely available, fast. Real-time assessment of
blood flow (color flow imaging).
Disadvantages: Highly operator dependent,
images in nonsequential format which makes
anatomy more difficult to appreciate.
Nuclear Medicine
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Used primarily for obtaining functional
information. Limited role in GU imaging.
Advantages: Lower radiation dose than CT, no
adverse effects except for radiation. A few
unique advantages, e.g. In-111 white blood cell
scanning is highly specific for infections.
Disadvantages: Long imaging times, few
specific indications, radiation.
Magnetic Resonance Imaging
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Increasing role in abdominal/pelvic
imaging
Advantages: Many imaging sequences
allow highly tailored studies, no
radiation, more specific than CT
Disadvantages: Cost, longer imaging
times than CT, unable to imaging
calcium (renal/ureteral calculi,
calcifications)
Plain Films
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Useful as a first test in several
applications: Renal calculi,
emphysematous pyelonephritis, renal
size.
Advantages: Cheap, fast, widely
available.
Disadvantages: Rarely diagnostic.
Further tests required.
Renal Imaging:
Radiologic Parameters
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In the more commonly used exams in
which contrast is given – CT, MRI, IVP –
and to a lesser extent, nuclear
medicine, images are obtained
dynamically.
Three phases defined: Arterial
(corticomedullary) 10-20 seconds;
Venous (nephrogram) 40-80 seconds;
excretory – beyond 80 seconds.
Arterial (corticomedullary)
phase – 10 to 20 seconds
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Renal artery
and vein
prominent
(arrows)
Cortex clearly
differentiated
from medulla
Venous (nephrographic) phase
40 – 80 seconds
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Vasculature
less
prominent
The cortex
and medulla
have the
same degree
of
enhancement
Excretory phase – beyond 80
seconds
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Most variable
phase
Begins when
contrast is
seen in the
collecting
systems
Renal Infections
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Pyelonephritis
Renal and perinephric abscess
Emphysematous pyelonephritis
Xanthogranulomatous pyelonephritis
Acute Bacterial Pyelonephritis
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Two main routes of infections: reflux
and blood borne.
Vesicoureteral reflux, primarily in
children, caused by E. coli
Hematogenous, usual cause of infection
in adults, caused by Staph aureus.
In uncomplicated infections, imaging
usually not necessary.
CT imaging of pyelonephritis
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In mild cases, there may be no imaging
findings.
The most specific finding is the “striated
nephrogram” – alternating stripes or
wedges of opacified and nonopacified
parenchyma caused by nonhomogeneous
edema
Focal defects, global enlargement, and
delayed opacification are other less
specific findings
Striated Nephrogram
Pyelonephritis with renal
enlargement
Renal/perirenal abscess
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CT is highly sensitive, but somewhat
nonspecific for abscesses.
The clinical picture of pyuria, flank pain,
fever, and tenderness with characteristic
findings are usually definitive.
CT shows a low attenuation region
without enhancement with a thick,
enhancing capsule, adjacent fascial
thickening, and fat stranding.
Renal abscess
Perinephric abscess
Emphysematous Pyelonephritis
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Emphysematous pyelonephritis is a lifethreatening infection of the kidneys in which
gas is produced. There are 2 types.
Type I: More than one third of the kidney
destroyed, no fluid collections. 70% mortality.
Type II: Less than one third of kidney
destroyed with fluid collections. Mortality
18%.
Usual treatment: nephrectomy.
Emphysematous
pyelonephritis
Emphysematous cystitis
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Gas in the bladder wall usually caused
by E. coli.
Occurs in diabetes, bladder outlet
obstruction, neurogenic bladder
If no other abnormalities present
(abscess, gangrene), usually responds
readily to antibiotics
Emphysematous cystitis
Emphysematous cystitis
Xanthogranulomatous
pyelonephritis
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Chronic indolent, renal infection
Renal parenchyma replaced by lipid
laden macrophages which can form
large masses.
Unusually entire kidney involved.
CT: Low attenuation masses, renal
enlargement, usually a calculus
(staghorn) present, renal enlargement.
Xanthogranulomatous
pyelonephritis
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Staghorn Calculus
Xanthogranulomatous
pyelonephritis
Renal Focal Lesions
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Renal cysts are the most common focal
renal lesion.
Cysts are ubiquitous with 50% of the
population older than 50 having a simple
renal cyst.
Simple cysts are easily recognized, but
complicated cysts are more difficult to
assess in terms of a benign or malignant
lesion.
BOSNIAK CLASSIFICATION
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I Simple Cyst : Nonoperative
II Septated, minimal calcium described
as “egg shell”, thin septa and walls,
high-density cysts (> 20HU), nonenhancing : Nonoperative
III Multiloculated, thick walled, dense
calcifications; nonenhancing solid
component: Renal-sparing surgery
IV Marginal irregularity, enhancing
solid component: Radical Nephrectomy
Simple
cyst
of RK:
Bosniak I
Bosniak II: Faint calcification
with hair thin septation ,
no contrast enhancement
Bosniak III:
lobulated,
cystic lesion
with irregular,
calcified
septum
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Bosniak IV: Cystic and solid lesion
with enhancing solid component:
Renal Cell Carcinoma
Angiomyolipoma
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Angiomyolipomas are hamartomas
containing fat, smooth muscle, and
blood vessels
Most are asymptomatic, but large
lesions (> 4 cm) may bleed.
80 % of pts with tuberous sclerosis
have AML, usually multiple lesions
bilaterally.
AML ; Large fatty mass of RK
pathognomonic finding
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AML in tuberous sclerosis
Ultrasound shows multiple, small, hyperechoic foci
representing fat containing lesions typical of AML
Oncocytoma
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Oncocytomas are benign renal tumors
with no metastatic potential but are
indistinguishable radiographically
from Renal Cell Carcinoma (RCC)
Biopsy is of little use because RCC can
contain elements of oncocytoma
If there is a strong suspicion that the
mass in question is benign, a renal
sparing procedure is an option
Testicular imaging
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Ultrasound is the method of choice
for imaging the scrotum and its
contents
The most common indications for
testicular imaging are torsion and
epididymitis/epididymo-orchitis
Scrotal anatomy
Testis (T) and epididymal head
(arrow): saggital image
T
Epididymitis
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Ultrasound image
Color flow image
Epididymo-orchitis with
hydrocele
Testicular abscess with hydrocele
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Ultrasound image
Color flow image
Right testis
Left testis
 Color flow images of both testes in a patient
with left sided scrotal pain shows no flow to the
left testis. It is important to compare both
testes using the same setting for color flow.
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Take Home Thought
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When I die, I want to go
peacefully, like my
grandfather, who died in his
sleep – not screaming like
the passengers in his car.
Renal Tuberculosis
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Putty Kidney
Emphysematous pyelonephritis
Ultrasound findings
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Longitudinal view
Transverse view
Renal Tuberculosis
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Uncommon infection in the United
States
Classic findings are from scarring with
parenchymal destruction and
obstruction from strictures
Calcifications can be prominent – Putty
kidney
Renal abscess with staghorn
calculus
Perinephric abscess
Renal abscess with staghorn
calculus