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Urinary Tract Imaging

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sihirlifil's version from 2017-12-04 15:15

Contrast studies (kidneys, ureters, bladder) & Ureter Ultrasound

Question Answer
Which Lat is better for kidney?R (separates L from R better)
Assessment of renal length on which view?VD
Possible causes of renal enlargementAcute inflam
Urinary obstruction
Diffuse neoplastic infiltration
Renal/perinephric cysts
What can be seen in contrast studies of the urinary tract?Kidneys, ureters (antegrade): excretory urography/IV pyelography/urography
Urinary bladder (ante/retro): cystography
Urethra (retrograde): urethrography
Renal vessels: selective angiography
Renal pelvis & ureters: US-guided antegrade phyelography
How is IVP/IVU/Excretory urography done?IV admin of water-soluble iodinated contrast medium (low volume-high concentration technique bolus IV injection OR high volume-low concentration technique, IV infustion of lower concentration over 10-15 min)
CM is excreted via glomerular filtration of the kidneys & collection system/urine
IVP/IVU/Excretory urography: indications?Imaging the kidneys and ureters (and bladder)
Kidneys: abnormal size, shape, margination on plain radiographs, evaluate perfusion, assess renal pelvis (hydronephrosis); marginal information on renal function (i.e. CM uptake yes/no; washout?)
Ureters: dimensions, suspected rupture, obstruction, suspicion of ectopic ureters, investigation of urinary incontinence, hematuria
Risk factors/contraindications of IVP/IVU?Dehydration/shock/hypotony
Anuria
(Known CM hypersensitivity)
Azotemia is not a contraindication
Prevention: adequate hydration before the study
Why does azotemia make IVP/IVU difficult?GFR is decreased
Iohexol/iopamdol CM for IVP/IVU are safer for who?Patients with existing renal disease
Dehydrated
Hypotonic
Possible complications of IVP/IVUNausea/vomiting/hypersalivation
Hypotony --> acute renal failure (no filtration of the CM, i.e. no visible pyelogram phase; renal phase static or increasingly radio-opaque
Acute renal failure from precipitation of proteins in the renal tubules
Anaphylactic shock (rare, caused by CM)
T/F Angiogram is only with low concentration techniqueFalse: only with high concentration/bolus technique
How are vessels opacified with angiogram?Arteries --> veins
What does an angiogram tell us about renal perfusion?Are both L&R renal aa opacified?
Renal vascularization
When do you take radiographs during an angiogram?During CM admin (~10-30 sec after beginning injection)
What is selective renal angiography? What is it for?Alternate way to visualise the renal arteries
Catheter inserted via femoral artery, contrast admin directly into respective renal artery
Which procedure? what's happening?
Selective renal angiography/arteriography
Contrast appears from caudal and opacifies the renal arteries. Renal pelvis not yet visible
How does a selective renal angio/arteriography differ from iVU?IVU: contrast reaches the kidney from cranial
Nephrogram = ? Evident when?Opacification of the kidneys, visible 1 min after contrast admin
What info does a nephrogram give?Size, shape, contour, location of the kidneys
How should a nephrogram look?Kidneys should show homogenous contrast accumulation
Filling defects/abnormal contrast accumulation may reflect a mass (neoplastic), abscess, cyst, ischemic areas such as infarcts
Nephrogram: CM accumulation is dependent onPlasma concentration (amount of CM)
GFR (stay opaque if low)
Osmolality in the tubules
What's this? Note about this?
Angiogram (nephrogram) of 2 cats
Contrast is present in vascular space & renal parenchyma (kidneys appear more opaque than adjacent ST structures)
Contrast is admin systemically, so it's visible in vasculature of other organs too! (lungs, spleen, GI)
Nephrogram of cat (normal: homogenous opacification of both kidneys)
Pyelogram = ? Evident when?Contrast in renal pelvis, 3-10 minutes after injection
Proximal ureters
How should a pyelogram look?Narrow sickle-shaped structure, ureters 2-3mm wide with gaps due to peristalsis
Pyelogram of cat
Arrows = renal pelvis, deer-antler appearance
Are ureters usually seen on plain radiographs?Nope! only if markedly enlarged (tortous tubular structures)
Ureterogram of cat (ureters = small orange arrows)
Yellow arrow: feces in colon; bottom orange = contrast arriving in bladder
Causes of ureter dilationObstruction: Iatrogenic (OVH ligature), ureteral urolith, papilloma/polyp, bladder trigone tumor involving ureter terminations, periureteral mass/stricture
Inflammation (ureteritis)
Ectopic ureter
Trauma
Ureteritis, canine (wide ureters, generalized dilatation
How do normal ureter terminations look w/ combined IVU & pneumocystogram?Hook-shaped end, inserts in trigone area of bladder
How do ectopic ureter terminations look w/ combined IVU & pneumocystogram?Ureter is dilated, tortuous, extends cd to the bladder neck
What are ectopic ureters? in who? what happens?Congenital malformation, mainly young femal (present before 1yo). Breed pred: Retriever, Entelbucher, Newfoundland, Mini poodle, Sib husky
Ureters terminate caudal to the trigone and can be intramural or extramural and uni/bilateral in urethra, vagina
What does IVU of ectopic ureters look like if they bypass the bladder completely?No contrast filling of bladder after IVU
CONTRAST IN THE BLADDER DOES NOT RULE OUT ECTOPIC URETERS
Bilateral ectopic ureters in a dog
Moderate hydronephrosis, severe hydroureters with signs of peristalsis, no evidence of connection to bladder (No CM there)
Unilateral ectopic ureter in a dog
Contrast present in both ureters, both peristalsis, one connected to bladder at trigone, the other continues caudally parallel to bladder neck
Contrast present within bladder lumen
Unilateral ectopic ureter (IVU)
Extremely distended ectopic R ureter, distended renal pelvis
Unilat ectopic ureter in a cat
Radiographic signs of ureter rupture (plain film)Increased retroperitoneal opacity
Reduced retroperitoneal detail
Poor margination of kidneys
Ureter rupture plain study
Radiographic signs of ureter rupture contrast studyExtravasation of CM
Ureteric dilatation proximal to rupture
If rupture is unilateral, bladder will fill normally
1Ureter rupture (contrast study)
Ureter rupture (contrast study)
Arrow = point of rupture, contrast medium leaking out
Indications for radiography of the bladder (Cd abdomen)Changes in urine: Color/hematuria, pollakiuria, dysuria
Pain at micturition
Suspicion of urolithiasis
Suspicion of obstruction
Suspicion of bladder rupture
Species? Problem?
Cat with massive bladder; Likely blocked
Loss of detail cd abdomen around bladder neck, prox urethral
Species? Problem?
Male dog (os penis)
Uroliths radiopaque
Try to see if there are more along the path of urethra
Uroliths: radio-opaqueCa Oxalate (+++)
Struvite (++)
Ammonium urate (+-)
Higher the Ca content = more radio-opaque
Uroliths: radiolucentCystine
Urate
Radio-opaque cystic uroliths extending into the bladder neck
Morphologic features of struviteAmorphous
Morphologic features of Ca OxalateSmall, spiky
Cystography = Imaging the urinary bladder
Can increase the contrast using iodinated CM or gas, administered via urinary catheter: retrograde
CM for cystography?Positive: Iodinated
Negaive: air, CO2, N2O
Double contrast study = iodine + gas
Method of choice to dx bladder ruptureCystography
Indications of Positive contrast cystography
Rupture/suspicion of rupture
Dislocation
Suspicion of bladder wall mass
Anatomical anomalies (vesicourachal diverticulum)
Cystic uroliths creating filling defects (pos contrast cystography)
Radiographic findings of bladder ruptureAbdominal effusion
+/- missing bladder shadow
Extravasation of CM when bladder is filled with CM
Bladder rupture with extravasation of CM
Negative contrast cystography to assess?Thickness of bladder wall (inflammation vs. tumor)
Position of bladder (trauma, adjacent organs, prostate)
Luminal structures: uroliths, blood clots, FB
CONTRAINDICATIONS OF NEGATIVE CYSTOGRAPHY:Severe hematuria = DANGER OF AIR EMBOLISM
Mass surrounded by gas in bladder (neg contrast)
Double contrast cystography used to assess?Bladder wall
Mucosal surface
Ureteral terminations
Double contrast cystography used to diagnose?Filling defects
Mucosal lesions
Wall-based masses
Double-contrast study showing pool of CM in dependent part of bladder 7 luminal gas
How do filling defects distribute differently?Central = cystic uroliths
Periphery & irregular = blood clots
Periphery & ROUND = gas bubbles
How does vesicourachal diverticulum look on radiographs? (double contrast)Pointed bladder apex, with CM accum there
(Can elevate the pelvis to fill diverticulum with contrast)
Vesicourachal diverticulum double contrast
Bladder wall lesions: ddx?Neoplasia
Polyps
Inflammation
Hge
Dx?
Transitional cell carcinoma in trigone area
Broad-based bladder wall lesion in dorsal bladder wall, dilation of distal ureter
Unilateral hydroureter (probably due to obstruction by the mass)
Indications for US of the lower urinary tractHydronephrosis
Suspicion of obstruction
Suspiciion of ectopic ureters
How do ureters look on US?Not normally visible
Become visible when distended i.e. ectopic ureters; mineralized ureteric calculi, thickened walls, luminal plugs
Ureterovesical junctions = ?Small paired elevations in the dorsal bladder wall (trigone area): colliculi, open & close as urine injected into bladder
May not be seen on US if bladder neck is too far caudal
Can see urine jet with color flow doppler
Ectopic ureters visible because distended
Color flow doppler of ureterovesical junction, both terminating in bladder (not ectopic)
(Ureteric jets at 3-6/min, increased after diuretic e.g. furosemide)
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Kidney probs (Chart from LN)

Question Answer
Mildly enlarged, smooth outline, bilateralAcute renal failure
Congenital PSS (+/- calculi)
Renal lymphoma (Cat!)
Amyloidosis
Acromegaly
Nephrogram phase of IVU
Dyctiophyma renale
Mildly enlarged, smooth outline, unilateralCompensatory hypertrophy
Renal neoplasia (NOT lymphoma)
Mildly enlarged, smooth outline, uni OR bilatAcute Glom/interstitial/pyelonephritis
Hydronephrosis
Subcapsular abscess, hematoma, urine
MARKEDLY enlarged, smooth, bilateralFIP causing pyogran nephritis- can also be irregular
MARKEDLY enlarged, smooth, uni OR bilatPerirenal pseudocysts CATS
Enlarged, IRREGULAR outline, bilateralPolycystic kidney disease (inherited)
Metastatic neoplasia
Enlarged, IRREGULAR outline, unilateralRenal cyst(s) or abscess
Primary renal neoplasia: renal cell CA, nephroblastoma, renal cystadenoma, hemantioma/-SA
Enlarged, IRREGULAR outline, uni OR bilatHematoma, granuloma
(small kidney, smooth or irregular, uni or bilat)(Chronic renal disease
Multiple infarcts --> parenchymal atrophy
Developmental hypoplasia/dysplasia
2ry to chronic obstruction
Amyloidosis in CATS)
Normal sizeAcute renal toxicity (ethylene glycol etc)
Amyloidosis
Early stages of all
Increased opacity, diffuseNephrocalcinosis
Cushing's, hyperPTH, hyperCa, ethylene glycol, tubulonephrosis, HOD, drugs
Increased opacity, focalNephrolith (dystrophic mineralization of renal parenchyma)
Calcified renal diverticula (cats)
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