Urinary Imaging Flashcards
What are the different imaging modalities we could use for the urinary system and what could we use them for? (4)
•Radiography
–Still an important tool, particularly presence/absence, size/shape, mineralisation, ruptures, complex spatial relationships
•Ultrasonography
–Extremely helpful, particularly kidneys and bladder
–Complementary to radiography
•CT (and MRI)
–CT being used increasingly, particularly ureters and urethra
–Contrast CT – gold standard
•Endoscopy
- Useful for direct visualisation of the bladder and urethra
When do we image in a urinary case?
•Concentrate on those cases where clinical signs are severe, or recurrent or persistent in the face of treatment as these are the cases which are more likely to have a physical changes which we can detect
clinical signs and other work-up must suggest changes within the urinary tract that will be detected by the chosen method
•What do we call this imaging plane of kidney? Where renal pelvis is asymmetrical at far edge of image?
•Frontal (dorsal) we are going from greater curvature of kidney in near field all the way through to reach the pelvis on other side
•What is NOT routinely visible on plain abdo radiograph? (2)
–Urethra
–Ureter
•On a VD of a dog abdo, what is the normal range for max renal length?
•2.5-3.5 x length L2
•Which radiograph contrast is used for kidneys?
•IV urogram
•Which radiographic contrast study will give the best mucosal detail in the bladder?
- Double contrast cystogream
- Positive – coat mucosa
- Air – see detail
•How many layers are visible in an U/S image of a normal bladder wall? What are they?
- 3
- Mucosal surface
- Muscle
- Serosa
What does this show?
Left – large soft tissue structure. Non contrast; non filtering enlarged L kidney
R – some contrast in ureter and leaving renal pelvis
What can we use IVU for in regards to kidnye function?
IVU provides only very crude assessment of renal function (excretion)
What do we do if one or both kidneys are not visible?
Investigate further
What is the effect of an enlared left kidney?
- Ventral displacement of colon
- Medial displacement of colon and small intestine
What is the effect of an enlarged right kidney?
- Ventral displacement of duodenum
- Medial displacement of ascending colon
What may a reduced renal size be associated with?
Change in shape +/- opacity
What causes reduced renal size? (2)
•Generally chronic renal disease (older) or dysplasia (young)
what is this?
Small kidney and abnormal ca
Was ist Das?
IVU
Mis-shapen – fibrotic
Small
What are the 2 ultrasound changes of the internal renal architecture?
Generalised increase in cortical echogenicity
Medullar rim sign
What causes generalised increase in cortical echogencitity? (3)
-non-specific change in many renal diseases, e.g. early nephritis or lymphoma, or incidental fat accumulation in cats.
What is the medullar rim sign?
-Hyperechoic band in outer medulla
What causes medullary rim sign? (4)
-Causes include hypercalcaemia, acute tubular necrosis, chronic renal disease, FIP
What are these and what is the significance?
Renal coritcal cysts
Fluid filed cavities.
You will see one or two cysts in the cortex! Often incidental. If you have many cysts e.g. polycystic kidney dx – reduce the amount of functional tissue = problems
what is this?
Dilation of renal pelvis
Chunky ureters
What is going on?
Hydronephrosis/ dilated ureters
What can be seen here?
Renal Cyst
Distorting normal renal pelvis anatomy!
Radiography useful but cant tell if ST mass or fluid filled (then use U/S in combo)
What is this?
- Beware superimposition shadows
- Especially in fat animals!
What is shown here?
- Renal medulla can appear very hypoechoic on U/S/
- Can look anechoic in some on some machines! Don’t just jump to renal pelvis dilation
- Can do an IVU if you aren’t 100%
What is going on?
Location
Have we got ectopic ureters? Contrast – very specific to find location
IVU
Retrograde
Pneumocystogram
Can see contrast in v (vagina)
Contrast in UA (urethra)
Contrast in UA we get a thin line which splits out into bladder (we have positive and air)
Dorsal have a wider band joining with ureter. Have proved ureter terminates in urethera!
What is this?
Dilated ureter (megaloureter/hydroureter)
Degree of hydronephrosis
Ectopic ureter
Closer to the kidney easier to see ureter
What is going on here?
Opacity
Ensure you take x ray of WHOLE abdo not just bladder
Thin arrow – ureteric calculi
Thick arrows – renal calculi!
What can be seen?
Only see one normal renal shadow
Arrow heads – increase ST opacity in an enlarged retropeeitonal space
What is this?
Ureteric rupture
Contrast leaking out!
What can be seen on this CT?
frontal image (normal)
What is this?
transverse of kidney
What is this?
Computed Tomography (CT) with contrast – go to for ureters Left – transverse through pelvis, bottom is bladder, 2 circular structures with contrast – ureters RHS normal and LHS is dilated.
What is this?
normal ureteric opening. Have a bladder, mid grey in dorsal part of bladder is urine. Ventral part is contrast. Contrast media is more dense and drops to the bottom. Can see a dribble of contrast dorsal through urine. It is urine coming out… tells u the ureters are normally terminating in the bladder.
What is this highlighting?
- Beware deep circumflex iliac arteries in retroperitoneal space
- Around L5 come out perpendicular to aorta! Get an opaque area.
Whats going on here?
Bladder neck in pelvis – abnormal
What are you thinking about this? What do you do?
Where’s the bladder?!
No sign of bladder in caudal
so did contrast
What is going on?
Caudally displaced
What can cause a reduced bladder size? (4)
–Very small bladder
- Animal has just urinated
- Bilateral ectopic ureters with bladder hypoplasia
- Ureteral rupture
–Bladder rupture
–Bladder displacement
–Peritoneal disease obscures shadow
What can cause bladder enlargement? (2)
•Bladder is highly distensible, so may appear very large in normal animals! Storage organ.
–e.g. if left in kennel for several hours with no opportunity to urinate before radiography!
•Neurological or mechanical causes of pathological enlargement
What is this? Describe the appearance
- Cystic calculi
- Echogenic, often with acoustic shadowing
- Reflect back U/S – echogenic with deep shadows
What can be seen?
Solitary radiopaque calculus
Contain heavy elements e.g. Ca or Mg
What is this?
Radiolucent calculi
They are soft tissue fluid opacity (wont show up against urine. Will need contrast or U/S
What is this?
Radiopaque calculi
What is the appearance of stuvite and calcium oxalate of radigraph?
Radiopaque
What is the appearance of cystine urate on radiograph?
Radiolucent
What is the appearance of acute cystitis on x ray?
- Changes are minimal
- There hasn’t been time for a physical change
What is this? Describe appearance
–Chronic cystitis
- Thickening may be localised(cranioventral)
- Thickening may be generalised
- Irregularity of wall
- Contrast adheres to the mucosa
Complete this table
What can be seen?
Polypod cystitis
Polyps (thick arrow) – finger like lucent projections attached to wall
Calculi (thin arrow) – rounded (irritated wall and led to polyp)
Air bubbles (arrow head) – polygon shape around catheter!
What is this?
Cystitis
Note: the change particulary CrV
Describe and diagnose
Polypoid cystitis
Marked irregularity
Double contrast
Diagnose
Mucosal neoplasia
what is the most common bladder neoplasia?
•Most common neoplasm = urothelial (ex-transitional) cell carcinoma
Where do bladder tumours often effect?
Dorsal wall/trigone
What is the appearance of bladder mucosal tumours?
- Irregular surface
- Protrude into lumen
- Positive contrast adherence
What is this?
Cranioventral bladder wall thickening and associated mass
Describe what you see
Bladder neck mass (blue arrow) and blood clots (yellow arrow)
What has been used to take this image?
Describe what is seen?
Double contrast
Concave with thickening
What is the appearance of bladder mucosal tumours?
- Fixed wall become rigid and distort shape
- May be no mucosal irregularity or mass and no contrast adherence
- If the tumour erodes through epithelium – get similar signs as the epithelial tumours
When filing the bladder for contrast imaging how full do you fill it?
Fill the bladder well, but do not apply too much pressure …….. “two day old party balloon”
Describe what you see!
Leakage of positive contrast medium through the bladder wall in a case of FLUTD.
The bladder wall was grossly intact.
Urothelium is so leaky – leaks through bladder wall!!! Leakage between urothelial cells
These are the same dog… Why the difference in appearance?
Take care interpreting wall thickness with small bladders
2 images from same dog! Just urinated.
Wall relatively thick on left.
What has caused this appearnce?
“Slice thickness” artefact
•Change probe direction
Increase in echogenicity in far side of bladder
What has caused this appearance?
Side/grating lobes artefact
- Reduce gain
- Knock the gain down in the near field to see this
What imaging is this?
Retrograde urethrogram
What imaging is this?
Retrograde vaginourethrogram
Describe what you see
Enlarged prostate
in perineal rupture
Urethra caudally displaced – as is bladder neck.
Describe what you see
Urethral compression – arrows
Problems urinating due to compression
What is this?
Urethral neoplasia
–Radiographic appearance NOT distinguishable from urethritis!!
–Marked irregularity of urethra – widened. Some erosion into bladder neck.
Describe what you see
Urethral rupture – positive contrast are the best way to look
Avulsed urethra off the bladder
What is this?
Urate calculi
What is this?
Urethrolithiasis - dog
What is this?
Urolithiasis
•Which calculi will not be seen on plain radiographs?
- Urate – contains no heavy elements
- (Struvite have Mg and ca in calcium oxalates)
•Which radiograph contrast study should be used to detect rupture of the bladder?
- Positive contrast
- Air will just move through the abdo and cant distinguish from bowel gas!
•Which abnormalities are indistinguishable from urethral neoplasia of positive contrast urethrogram?
•Urethritis
Accidentally added this FC..
CBA to delete it..
What is the normal shape and size of canine kidneys?
- 2.5-3.5 x length of L2 (VD)
- Right kidney
- Located approx T13-L1/2
- Cranially in contact with the caudate love of the liver (may not see this margin)
- Left kidney:
- Usually slighlt further cauda and ventral
- Seperation of kidneys more obvsious on a RLR view
What is the normal shape and size of feline kidneys?
- Tend to be more oval in shape
- More frequently super imposed
- More caudally positioned
- Cranial pole of kidney more often seperated from the liver by fat
- Normal size
- 2-3 x L2
What is IVU?
Positive contrast media
Provides anatomical and functional info
Specific informattion can be obtained at each stage of the IVU, and the actual technique may need to be varied according to the findings at each stage
What are the contraindications of IVU?
Dehydration/hypovolaemia
Severe renal failure/anuria
How do you prepare for IVU?
Starve 24
Thorough cleansing enema
GA
What is the technique of IVU?
High concentration/low volume = inject bolus into peripheral vein
Low concentration/high volume - contrast given in IV drip
Several radiographs taken to track the flow of contrast through urinary tract
What do you do for IVU high concentration low volume.
•Immediate VD view (0 mins) = angiogram
- Opacification of renal vessels
- Rapid phase, easy to miss
•0-1 minutes VD view = nephrogram
–Uniform opacification of renal parenchyma in both kidneys
- (Negative contrast has been placed into bladder - pneumocystogram)
- 5 minutes VD view = pyelogram
–contrast within renal pelvises and ureters
- Normal pelvic width no more than 2-3mm
- Ureteral width approx 2-3mm
–Interrupted ureteral filling is a normal finding due to peristalsis
•10-15 minutes
–Both ureters should run caudally in the retroperitoneal space to terminate at the bladder trigone
How is the bladder often seen on radiographs?
Where is the normal urethra on plain radiograph?
Not visible!!
What is this?
Stifle fabellae may be super imposed on poorly positioned mages and cofused with calculi
What are the contrast radiography of the bladder? (3)
- Pneumocystogram
- Positive contrast cystogram
- Double contrast cystogram
What is bladder contrast readiographs useful for?
–Identification of bladder location
–Investigation of possible rupture
–Detection of radiolucent calculi
–Evaluation of the bladder wall
- Wall thickening
- Masses
- Mucosal surface
What is this?
Double contrast cystogram – chronic cystitis in a cat
What do we do for retrograde cystogram?
Survery films
Cathertise/empty/bladder
Inject contrast medium
What are the retrograde cystogram contrast medias? What are the advantages? (3)
What is this?
Incomplete filling - pneumocystogram
- Inadequate distention of the bladder or urethra is a major cause of poor diagnostic quality with retrograde contrast studies
- Here, the bladder is not fully distended resulting in an irregular shape
- There are also air bubbles in the residual urine in bladder resulting in a honeycomb appearance. This can be avoided by less enthusiastic injection of air through the catheter
What is this?
Artefactual indentation of the bladder wall – positive contrast urethrocystogram
•Again, this bladder is not fully distended with contrast medium
As a result, faeces pressing on the bladder are resulting in an indentation of the dorsal bladder wall
What is this?
- The urinary catheter has been inserted too far into the bladder and is twisting around the wall
- This should be avoided by measuring the catheter against the body before inserting
- Inserting it too far into the bladder may cause iatrogenic damage to the mucosa, and in extreme circumstances it can form a knot when attempting to pull it out, making it impossible to remove (a cystotomy will be necessary!)
How do you do a retrograde vaginourethrogram?
Foley catheter or urinary catheter plus clamp
Injecte diluted iodine contrast media
- Test injection for leaks
- CAREFUL injection - vaginal rupture
Lateral views are suually most helpful, VD view may be helpful for some abnormalities
How do you do a retrograde urethrogram?
Catheterise urethra
Position tip distal to area under investigation
Clamp sheath tightly around catheter
Inject diluted water soluble contrast medium (can mix1:1 with sterile aq gel)
Exposure immediately after end of injection - observe all radiation safety rules
Lateral views are usually most helpful
What are the ultrasound views of the kidneys?
What is the renal anatomy of the ultrasound of the kidney?
What can you see on the mid sagittal section view of renal anatomy?
–The hypoechoic medulla reappears central to the more echogenic cortex
–The pelvic diverticulae are prominent and can be seen as short, evenly-spaced echogenic “islands” traversing the medulla to the cortex (= the fingers of your hands being ’cut’ in transverse section - arrows)
–The renal crest is seen as a hyperechoic line running transversely across the kidney (= the paper)
What can you see on mid transvere section of the renal antomy U/S?
–The medial renal pelvis and peri-pelvic fat can be identified as an echogenic area positioned medially (= the touching palms of your hands)
–The dorsal and ventral parts of the renal pelvis appear as diverging hyperechoic lines (= the separated palms of your hands)
–The renal crest is seen as a hyperechoic line between the pelvic lines (= the paper)
–Cortex and medulla can be identified by their normal appearance
What can be seen in the frontal (dorsal) plane of the renal anatomy?
•Frontal plane – similar appearance to sagittal plane except:
–Eccentric position of the renal pelvis – seen medially in the far field (= palms of hand)
–Diverticulae appear to be longer because they are ‘cut’ through their long axis (= fingers)
–Cortex and medulla appear as usual
What is there a correlation in size of the kidney with in the dog?
•In dogs, there is a correlation between renal size and weight of dog or use kidney:aorta ratio
What is the normal cat kidney length?
3-4.5cm
What is a small and large kidney size in relation to kidney:aorta?
Small if kidney:aorta < 5.5
Large if kidney:aorta > 9.1
What is the normal ultrasound appearance of the bladder?
- Pear-shaped appearance on sagittal section
- Rounded appearance on transverse section
- Degree of distension affects shape, size and wall thickness
What are the 3 bladder layers?
- Inner mucosal interface (hyperechoic)
- Muscle layer (hypoechoic)
- Outer serosal layer (hyperechoic)
What is the normal dog bladder thickness?
•+/- 2.3 mm (minimally distended) – +/- 1.4mm (mod. Distended)
What is the normal cat bladder thickness?
•1.3-1.7mm
