Genitourinary Radiology

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Genitourinary Radiology

• Jerry Glowniak, MD
• Department of Radiology
• Detroit Receiving Hospital
• Detroit Medical Center/Wayne State University

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Radiological AnatomyKidneys and adjacent spaces

• 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.

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Retroperitoneal Spaces

• 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.

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The Perinephric Spaces

• 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 (Gerotas fascia,
  anterior renal fascia) and thinner posterior
  component (Zuckerkandls fascia, posterior renal
  fascia).

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Retroperitoneal Spaces Abdomen

• AC Ascending Colon
• DC Descending Colon
• D Duodenum
• K Kidney
• A Aorta
• V Vena Cava

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Anterior Pararenal Space

• 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

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Posterior Pararenal Spaces

• 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.

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Retroperitoneal Spaces Detailed View

• DC Descending Colon
• K Kidney
• PM Psoas Muscle

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Imaging Modalities

• Intravenous pyelogram
• Computed Tomography (CT)
• Ultrasound
• Nuclear Medicine
• Magnetic Resonance Imaging (MRI)
• Plain Film

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Intravenous Pyelogram

• 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).

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Computed Tomography

• Imaging modality of choice for most
  abnormalities.
• Advantages Fast, widely available, high
  resolution.
• Disadvantages Radiation, intravenous contrast,
  less specific than MRI

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CECT kidneys 4 min ( pyelogram phase), showing
excretion of contrast into collecting system,
would show urothelial lesions well, such as TCC
, stones, blood clots

• CECT kidneys, 60 sec (nephrogram phase) ,
•   would show renal parenchymal lesions well

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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.

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• 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.

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Ultrasound

• 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.

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Nuclear Medicine

• 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.

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Magnetic Resonance Imaging

• 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)

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Plain Films

• 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.

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Renal Imaging Radiologic Parameters

• 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.

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Arterial (corticomedullary) phase 10 to 20
seconds

• Renal artery and vein prominent (arrows)
• Cortex clearly differentiated from medulla

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Venous (nephrographic) phase 40 80 seconds

• Vasculature less prominent
• The cortex and medulla have the same degree of
  enhancement

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Excretory phase beyond 80 seconds

• Most variable phase
• Begins when contrast is seen in the collecting
  systems

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Renal Infections

• Pyelonephritis
• Renal and perinephric abscess
• Emphysematous pyelonephritis
• Xanthogranulomatous pyelonephritis

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Acute Bacterial Pyelonephritis

• 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.

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CT imaging of pyelonephritis

• 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

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Striated Nephrogram
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Pyelonephritis with renal enlargement
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Renal/perirenal abscess

• 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.

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Renal abscess
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Perinephric abscess
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Emphysematous Pyelonephritis

• Emphysematous pyelonephritis is a
  life-threatening 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.

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Emphysematous pyelonephritis
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Emphysematous cystitis

• 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

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Emphysematous cystitis
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Emphysematous cystitis
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Xanthogranulomatous pyelonephritis

• 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.

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Xanthogranulomatous pyelonephritis

• Staghorn Calculus

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Xanthogranulomatous pyelonephritis
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Renal Focal Lesions

• 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.

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BOSNIAK CLASSIFICATION

• I Simple Cyst Nonoperative
• II Septated, minimal calcium described as egg
  shell, thin septa and walls, high-density cysts
  (gt 20HU), non-enhancing Nonoperative
• III Multiloculated, thick walled, dense
  calcifications nonenhancing solid component
  Renal-sparing surgery
• IV Marginal irregularity, enhancing solid
  component Radical Nephrectomy

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Simple cyst of RK Bosniak I
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• Bosniak II Faint calcification
• with hair thin septation ,
• no contrast enhancement

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Bosniak IIIlobulated, cystic lesionwith
irregular, calcified septum
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• Bosniak IV Cystic and solid lesion with
  enhancing solid component Renal Cell Carcinoma

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Angiomyolipoma

• Angiomyolipomas are hamartomas containing fat,
  smooth muscle, and blood vessels
• Most are asymptomatic, but large lesions (gt 4 cm)
  may bleed.
• 80 of pts with tuberous sclerosis have AML,
  usually multiple lesions bilaterally.

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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

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Oncocytoma

• 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

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Testicular imaging

• 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-orc
  hitis

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Scrotal anatomy
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Testis (T) and epididymal head (arrow) saggital
image
T
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Epididymitis

• Ultrasound image Color flow image

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Epididymo-orchitis with hydrocele
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Testicular abscess with hydrocele

• Ultrasound image Color flow image

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• 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

• When I die, I want to go peacefully, like my
  grandfather, who died in his sleep not
  screaming like the passengers in his car.

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Renal Tuberculosis

• Putty Kidney

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Emphysematous pyelonephritisUltrasound findings

• Longitudinal view Transverse view

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Renal Tuberculosis

• Uncommon infection in the United States
• Classic findings are from scarring with
  parenchymal destruction and obstruction from
  strictures
• Calcifications can be prominent Putty kidney

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Renal abscess with staghorn calculus
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Perinephric abscess
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Renal abscess with staghorn calculus