IMAGING - Urinary System Flashcards by Emily Hunter

What are the limitations of radiography when imaging the urinary system?

Fluid and soft tissue have the same opacity
Kidneys and bladder may not always be visible
Can often only see marked changes in radio-opacity and size

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Why is the right kidney more difficult to visualise on radiography?

The right kidney is often superimposed onto the liver on radiography

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What are the main applications of radiograph contrast studies when imaging the urianry system?

Radiograph contrast studies are useful for assessing for urinary tract ruptures and to assess the intrapelvic structures of the kidneys

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What are negative based radiograph contrast studies?

Negative based contrast studies is where air is used to provide contrast as air will decrease the x-ray attenuation making the structures containing these agents appear darker on the radiograph

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What are positive based radiograph contrast studies?

Positive based contrast studies is where iodine based contrast mediums are used to increase the x-ray attenuation, making the structures containing these agents appear brighter on the radiograph

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Which routes of administration can be used for contrast radiography of the urinary system?

Intravenous urography (IVU)
Retrograde urethral cystography

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What is intravenous urography (IVU)?

Intravenous urography (IVU) is where the contrast medium is administered via the cephalic vein and demonstrates the kidneys and the ureters

|Can only be done with positive contrast methods

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What is retrograde urethral cystography?

Retrograde urethral cystography is where the contrast medium is administered via a urinary catheter to demonstrate the urethra and the bladder

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Why is it so important to correctly position your urinary catheter when doing retrograde urethral cystography?

It is important to position your urinary catheter so that the contrast doesnt spill out but also at the distal end of the urethra in order to visualise as much of the urethra as possible

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What should be done before taking contrast radiographs of the urinary system?

Plain radiographs
Enema

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Why should an enema be done prior to contrast radiography of the urinary system?

An enema should be done prior to contrast radiography of the urinary system as the colonic content can both mask and imitate pathological changes in the urinary system

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Which ultrasound view of the normal kidneys is this?

Long axis view of the kidney

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Which ultrasound view of the normal kidneys is this?

Short axis view of the kidney

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Why is the right kidney more difficult to visualise on ultrasound?

The right kidney is more dorsal and cranial than the left kidney and can be tucked into the ribs

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How does the appearance of the kidneys differ in cats compared to dogs?

In cats, the kidneys are more mobile and have a more rounded outline than in dogs. Cats are also more likely to have a corticomedullary rim sign which can be completely normal in cats

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Which factors should you assess when assessing the kidneys on diagnostic imaging?

Location
Size
Shape
Margins
Internal structures
Echogenicity
Echotexture

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What are the internal structures of the kidneys that you should assess on ultrasound?

Renal cortex
Renal medulla
Corticomedullary junction
Renal pelvis

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What are the differential diagnoses for changes in the renal parenchyma on diagnostic imaging?

Acute renal disease
Chronic renal disease
Chronic endstage kidney disease
Renal dysplasia
Neoplasia

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What are the key signs of acute renal disease on ultrasound?

Renomegaly
Rounded, hazy looking kidney
Retroperitoneal effusion
Reduced corticomedullary definition
Corticomedullary rim signs
Hyperechogenicity

Acute renal disease can look normal on ultrasound

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What are the key signs of chronic renal disease on ultrasound?

Bilateral changes (both kidneys)
Heterogenous renal cortices
Reduced corticomedullary definition
Indentations

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What is indicated by indentations in the renal surface on ultrasound?

Indentations on the renal surface on ultrasound indicate chronic infarcts

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What is renal dysplasia?

Renal dysplasia a congenital renal disease where one or both kidneys do not develop normally in utero

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What are the signs of renal dysplasia on ultrasound?

Reduced corticomedullary definition
Abnormal margins of the kidney
Small kidney

|Usually presents in young animals but can be seen in older animals

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What are the signs of chronic end stage kidney disease on ultrasound?

Disruption of normal renal architecture
Small kidney

|Usually presents in older animals

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What are the differential diagnoses for renal pelvis dilatation on diagnostic imaging?

Hydronephrosis due to urinary obstruction Pyelonephritis Neoplasia

What is hydronephrosis?

Hydronephrosis is the dilatation of the renal pelvis as a results of a urinary flow obstruction

What are the key signs of hydronephrosis on ultrasound?

Dilated renal pelvis Dilated ureter

What should you do if you identify hydronephrosis on ultrasound?

If you identify hydronephrosis on ultrasound you should use the ultrasound to follow the ureter to identify the site of urinary obstruction and check the other kidney and ureter for any changes

What are the key signs of pyelonephritis in the kidneys?

Dilated renal pelvis with thickening and irregular margins of the renal pelvis

What are the key signs of renal neoplasia on ultrasound?

Disruption of normal renal architecture Enlarged lymph nodes

Which further diagnostics should you do if you suspect renal neoplasia on ultrasound?

Further diagnostic imaging *(radiography and CT)* Fine needle aspirate (FNA) Biopsy

What are the differential diagnoses for focal changes in the kidneys on diagnostic imaging?

Renal caliculi Renal cysts Renal abscesses Renal neoplasia

(T/F) All caliculi can be visualised on radiography and ultrasound

FALSE. All caliculi can be seen in ultrasound however only radio-opaque caliculi can be visualised om radiography

Which calculi are visible on radiography?

Struvite Oxalate

Which calculi are **not** visible on radiographs?

Purines

What are the key signs of renal calculi on ultrasound?

Focal hyperechoic areas with acoustic shadowing in the renal pelvis

What should you do if you identify renal caliculi on ultrasound?

If you identify renal caliculi on ultrasound you should assess the ureters for evidence of caliculi which could cause obstruction

What are the key signs of renal cysts on ultrasound?

Well defined, anechoic mass with distal acoustic enhancement

What is distal acoustic enhancement?

Distal acoustic enhancement refers to the hyperechoic area distal to structures that are excellent transmitters of sound waves, such as fluid

What are the general causes of renal cysts?

Congenital cysts Chronic inflammation Polycystic kidney disease (PKD)

What are the key signs of renal abscesses on ultrasound?

Anechoic to heterogenous mass with irregular margins Heterogenous, hyperechoic surrounding reactive fat

What is the normal appearance of the bladder on ultrasound?

Anechoic contents Bladder wall which can vary in thickness depending on how full the bladder is

Which factors should you assess when assessing the bladder on diagnostic imaging?

Location Size Shape Margins Internal contents

What are the differential diagnoses for changes in the bladder wall on diagnostic imaging?

Cystitis Mass Bladder rupture

What are the key signs of cystitis on ultrasound?

Increased bladdder wall thickness when the bladder is full *(as when it is empty the wall will appear thicker even if there is no pathology)*

What are the differential diagnoses for a bladder mass?

Neoplasia Inflammatory polyps

What are the key differences between bladder neoplasia and inflammatory polyps on ultrasound?

Inflammatory polyps are more likely to extend into the lumen and are not going to alter the adjacent urinary bladder wall whereas neoplasia is more likely to cause a loss of layering of the bladder wall and have hyperechoic reactive fat around the bladder wall and possibly enlarged lymph nodes

Which neoplasm is indicated by heterogenous hyperechoic fat around the bladder wall?

Transitional cell carcinoma

What further investigation should you do if you suspect bladder neoplasia?

Further diagnostic imaging *(radiography and CT)* Fine needle aspirate (FNA) Biopsy

What are the potential signs of bladder rupture on ultrasound?

Bladder wall thickening Anechoic fluid outside the bladder

How do you gain a definitive diagnosis for a ruptured bladder?

Retrograde urethral cystography with extravasation of the contrast and loss of serosal detail due to free fluid in the abdomen

What are the differential diagnoses for changes in the bladder contents on diagnostic imaging?

Bladder caliculi/sediment Emphysematous cystitis Cellular debris

What are the key signs of bladder caliculi/sediment on ultrasound?

Hyperechoic lines with acoustic shadowing

How do you differentiate between iatrogenic gas in the bladder from emphysematous cystitis?

Gas can be introduced into the bladder iatrogenically via urinary catheter placement or enema however this gas will typically sit in the centre of the bladder. With emphysematous cystitis, small gas bubbles tend to adhere to the bladder wall

What can be indicated by heterogenous, mobile content within the bladder on ultrasound?

Concentrated urine Haemorrhage Mucus Blood clot

How do you locate the prostate on ultrasound?

To locate the prostate on ultrasound, follow the urethra from the bladder and you should be able to identify the urethra

How does the prostate appear on ultrasound?

Biloped structure Echogenicity similar to the spleen Hyperechoic capsule

How does the appearance of the prostate differ in castrated animals on ultrasound?

The prostate will appear smaller on ultrasound in castrated males

Which factors should you assess when assessing the prostate on diagnostic imaging?

Location Size Shape Margins Echogenicity Echotexture

What are the differential diagnoses for parenchymal changes in the prostate on diagnostic imaging?

Benign prostatic hyperplasia Prostatitis Neoplasia

Which signalement typically presents with benign prostatic hyperplasia?

Older, entire male dogs

What are the key signs of benign prostatic hyperplasia on ultrasound?

Symmetric prostamegaly Homogenous and hyperechoic parenchyma ± Interparenchymal cysts No disruption of the prostatic capsule No lymphadenopathy | However the appearance can range between cases

What are the key signs of prostatitis on ultrasound?

Asymmetrical prostamegaly *(can depend on the presence or absence of cysts or abscesses)* Mixed echogenicity Hyperechoic, reactive periprostatic fat ± Periprostatic fluid ± Lymphadenopathy

What are the key signs of prostatic neoplasia on radiography?

Asymmetrical prostamegaly Mineralisation ± Lymphadenopathy *(medial iliac lymph nodes)*

What are the key signs of prostatic neoplasia on ultrasound?

Asymmetrical prostamegaly Heterogenous parenchyma Irregular margins of the prostate Hyperechoic, reactive periprostatic fat Mineralisation ± Lymphadenopathy *(medial iliac lymph nodes)*

What further investigation should you do if you suspect prostatic neoplasia on ultrasound?

Further diagnostic imaging *(e.g. radiography and CT)* Fine needle aspirate (FNA) Biopsy

What are the differential diagnoses for fluid filled lesions on the prostate on diagnostic imaging?

Prostatic cyst Prostatic abscess Paraprostatic cyst

What are key signs of prostatic cysts on ultrasound?

Well defined, anechoic mass with distal acoustic enhancement

What are key signs of prostatic abscesses on ultrasound?

Anechoic to heterogenous mass with irregular margins Hyperechoic reactive periprostatic fat

What is a paraprostatic cyst?

Paraprostatic cysts are cysts that extend beyond the parenchyma with a narrow stalk

What are the features of a paraprostatic cyst on radiography?

Soft tissue opacity mass Extends outside of the parenchyma of the prostate with a narrow stalk ± Thin egg shell appearance Dorsal displacement of the colon Double bladder sign

Identify this pathology on ultrasound

Paraprostatic cyst