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Genitourinary Radiology. Jerry Glowniak, MD Department of Radiology Detroit Receiving Hospital Detroit Medical Center/Wayne State University. Radiological Anatomy: Kidneys and adjacent spaces. - PowerPoint PPT Presentation
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Genitourinary Radiology
Jerry Glowniak, MDDepartment of RadiologyDetroit Receiving Hospital
Detroit Medical Center/Wayne State University
Radiological Anatomy:Kidneys 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.
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.
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 (Gerota’s fascia, anterior renal fascia) and thinner posterior component (Zuckerkandl’s fascia, posterior renal fascia).
Retroperitoneal Spaces: Abdomen
AC – Ascending Colon
DC – Descending Colon
D – Duodenum K – Kidney A – Aorta V – Vena Cava
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
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.
Retroperitoneal Spaces: Detailed View
DC – Descending Colon
K – Kidney
PM – Psoas Muscle
Imaging Modalities
Intravenous pyelogram Computed Tomography (CT) Ultrasound Nuclear Medicine Magnetic Resonance Imaging (MRI) Plain Film
Intravenous Pyelogram
Gold Standard 20 years ago Becoming an obsolete technique Limited views of kidneys Two dimensional technique Largely replaced by CT
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
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
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.
1 2
3
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 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 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 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 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 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
Renal artery and vein prominent (arrows)
Cortex clearly differentiated from medulla
Venous (nephrographic) phase 40 – 80 seconds
Vasculature less prominent
The cortex and medulla have the same degree of enhancement
Excretory phase – beyond 80 seconds
Most variable phase
Begins when contrast is seen in the collecting systems
Renal Infections
Pyelonephritis Renal and perinephric abscess Emphysematous pyelonephritis Xanthogranulomatous
pyelonephritis
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.
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
Striated Nephrogram
Pyelonephritis with renal enlargement
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.
Renal abscess
Perinephric abscess
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.
Emphysematous pyelonephritis
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
Emphysematous cystitis
Emphysematous cystitis
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.
Xanthogranulomatous pyelonephritis
Staghorn Calculus
Xanthogranulomatous pyelonephritis
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.
BOSNIAK CLASSIFICATION
I Simple Cyst : Nonoperative II Septated, minimal calcium described
as “egg shell”, thin septa and walls, high-density cysts (> 20HU), non-enhancing : 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 lesionwith
irregular, calcified septum
Bosniak IV: Cystic and solid lesion with enhancing solid component: Renal Cell Carcinoma
Angiomyolipoma
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
AML in tuberous sclerosis Ultrasound shows multiple, small, hyperechoic
foci representing fat containing lesions typical of AML
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
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-orchitis
Scrotal anatomy
Testis (T) and epididymal head (arrow): saggital image
T
Epididymitis Ultrasound image Color flow image
Epididymo-orchitis with hydrocele
Testicular abscess with hydrocele
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.
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.
Renal Tuberculosis Putty Kidney
Emphysematous pyelonephritis
Ultrasound findings
Longitudinal view Transverse view
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
Renal abscess with staghorn calculus
Perinephric abscess
Renal abscess with staghorn calculus