Ultrasonography of the Upper Urinary Tract

The Student will be able to:
Ultrasonography of the
Upper Urinary Tract
Kari L. Anderson, DVM, DACVR
Associate Clinical Professor
University of Minnesota
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List indications and describe protocol for
sonography of the kidneys/ureters
Recognize and describe normal anatomy and
sonographic appearance of kidneys/ureters
Recognize diffuse and focal lesions of the
kidneys/ureters and generate appropriate
differential lists
Recognize and describe the sonographic
appearance of selected diseases
Select which diseases are likely to yield a
diagnosis when sampled and describe sampling
UUT Ultrasound
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Routine procedure providing important
information
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Size and shape of kidneys
Internal architecture
Provides more information than
conventional radiographs
 Guide procedures
 May need to consider excretory
urography
Indications
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Evaluate abnormal
radiographic findings:
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Evaluate internal renal
architecture
Azotemia/uremia
Hematuria
Recurrent urinary tract
infections
Cranial retroperitoneal mass
Screening for PKD
US Analogy
Imaging Protocol
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Transducer
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Highest frequency (>7.5 MHz); may need
lower frequency in certain cases
Scan plane
Patient in dorsal recumbency
Obtain sagittal and transverse images,
supplemental dorsal images
 Right kidney window may be through 11-12th
intercostal space
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=
Abnormal size, shape, position,
non-visualized
Normal Sonographic Appearance
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Normal Sonographic Appearance
medulla
Location
Left kidney: caudal to stomach, medial and
dorsal to spleen body, lateral to aorta
 Right kidney: renal fossa of caudate liver lobe,
dorsal and medial to duodenum, lateral to
cava, more cranial than left
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cortex
Anatomy
US appearance
Glomeruli
 Bright central echo
 Renal tubules
complex
 Interstitium (CT, capillary network,
 Outer medium
lymphatic tissue, smooth muscle cells)
echogenicity
 Vessels
 Inner hypoechoic region
 Pelvis, renal recesses
 Echogenic capsule
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Normal Sonographic Appearance
Renal vein
Anatomy
US appearance
Glomeruli
 Bright central echo
 Renal tubules
complex
 Interstitium (CT, capillary network,
 Outer medium
lymphatic tissue, smooth muscle cells)
echogenicity
 Vessels
 Inner hypoechoic region
 Pelvis, recesses
 Echogenic capsule
Normal Sonographic Appearance
Comparative parenchymal
organ echogenicity
 Renal sinus > spleen >
liver ≥ renal cortex >
renal medulla
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Normal Variation
Normal Sonographic Appearance
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Normal size
Radiographs best
Subjective in dogs
 Cats more standard
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 Length
3.66±0.46 cm
2.53±0.3 cm
 Height 2.21±0.28 cm
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The cortex of the cat is
more echogenic than
that of the dog
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 Width
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Fat vacuoles in cortical
tubular epithelium
accumulation increases
with age
Normal Variation
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Normal Variation
Findings with diuresis:
Increased size of
medulla
 Minimal bilateral or
unilateral pyelectasis
(<2-3 mm)
 NO ureterectasis
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Medullary rim sign
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normal
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mild dilation
Normal Sonographic Appearance
Abnormal Sonographic Appearance
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Long axis movie
Transverse axis movie
Diffuse Abnormalities
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 Increased
Preserved CM differentiation
Non-specific
Many differentials
Amyloidosis
Lyme nephritis
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Patterns and echogenicity
more specific for
focal/multifocal lesions
Often non-specific for diffuse
lesions
Limited use to distinguish
between benign and
malignant
Must correlate findings with
other information
Diffuse Abnormalities
Increased cortical echogenicity
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Non-specific and often
normal in dogs and cats
Thin linear hyperechoic
band in outer of medulla
Microscopic deposits of
mineral
If only finding, 72% dogs
no renal dysfunction
In combination with other
findings, 78% dogs had
renal disease
ATN
cortical echogenicity
Glomerulonephritis
Diffuse Abnormalities
 Increased
cortical echogenicity
Diffuse Abnormalities
 Increased
overall echogenicity
 Decreased
CM differentiation
 Differentials
 Chronic
 Renal
inflammatory diseases
dysplasia
 GN
Renal lymphoma
Hypercalcemic nephropathy
Diffuse Abnormalities
 Increased
overall echogenicity
Diffuse Abnormalities
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Increased overall
echogenicity
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“end-stage” kidney
 Small
and irregularly
shaped
 Poor visualization of
internal architecture
Chronic pyelonephritis
Diffuse Abnormalities
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Decreased echogenicity
Focal Abnormalities
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Ill-defined multifocal
hypoechoic nodules of
lymphoma
 Edema in acute diseases
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Renal cyst
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Characteristics:
 Round
or ovoid
cyst
far enhancement
 Echo-free
 Thin
walls
enhancement
cyst
 Acoustic
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Renal lymphoma
Solitary or multiple
Acquired or congenital
far enhancement
Focal Abnormalities
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Renal cyst
Polycystic Kidney Disease
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Multiple cysts derived from renal tubules
Inherited
Often associated with CRF
cyst
far enhancement
Long axis
Transverse axis
Focal Abnormalities
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Renal cysts
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Focal Abnormalities
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Other differentials if thick or irregular walls,
internal septations, echogenic contents
Renal cysts
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Other differentials if thick or irregular walls,
internal septations, echogenic contents
thick capsule
cavitation
cavitation
Complicated cyst
Necrotic tumor
Focal Abnormalities
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Renal cysts
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Focal Abnormalities
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Other differentials if thick or irregular walls,
internal septations, echogenic contents
Cavitary metastasis
Renal cysts
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Other differentials if thick or irregular walls,
internal septations, echogenic contents
Renal abscess
Focal Abnormalities
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Focal Abnormalities
Renal nodules and
masses
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Renal nodules and masses
Commonly neoplastic
Variable – hypoechoic,
isoechoic, hyperechoic
 Lymphoma
often uniformly
hypoechoic
 May be cavitary
Renal lymphoma
Renal lymphoma
Focal Abnormalities
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Renal nodules and masses
Focal Abnormalities
subcapsular
infiltrate
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Renal nodules and masses
nodule
Round cell neoplasia
Renal lymphoma
Focal Abnormalities
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Focal Abnormalities
Renal nodules and masses
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Primary renal tumor rare – adenocarcinoma
Often begin at one pole
May affect both kidneys
Renal nodules and masses
mass
mass
Renal adenocarcinoma
Renal cell carcinoma
Focal Abnormalities
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Focal Abnormalities
Renal nodules and masses
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Renal adenocarcinoma
Renal nodules and masses
Liver metastatic nodule
Nasal carcinoma met
Focal Abnormalities
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Focal Abnormalities
Renal infarct
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Wedge-shaped
Acute – hypoechoic
Chronic – hyperechoic
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Hyperchoic areas in cortex
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Causes: neoplasia, calcification, fibrosis, gas
Acute infarct
Unknown cause of mineralization
Chronic infarct
Specific “Diseases”
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Acute Renal Failure
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Specific “Diseases”
Acute Renal Failure
US often normal
 May
be enlarged
may be hyper- or
hypoechoic
 May see perirenal fluid
 Cortex
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Diseases that cause
tubular necrosis or
ischemia
Meloxicam toxicity in a cat
Leptospirosis
Specific “Diseases”
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Specific “Diseases”
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Chronic Renal Failure
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Chronic Renal Failure
Non-specific findings:
 Normal
to hyperechoic,
irregularly shaped kidneys
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US generally not indicated
Causes:
 GN,
PKD, autoimmune disease,
nephrotoxins, tubular diseases,
pyelonephritis, etc
Specific “Diseases”
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Specific “Diseases”
Chronic Renal Failure
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spleen
Renal Dysplasia
Anomalous development
Familial forms
 Findings similar to any
chronic infiltrative dz
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 Hyperechoic,
poor CM diff,
abnormal architecture
 Diagnosis based upon young
age and renal biopsy
Glomerulonephritis
Specific “Diseases”
Specific “Diseases”
Halo sign
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Ethylene Glycol Nephrosis
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Hyperechoic cortex
Medullary rim sign
Halo sign
DDx: acute tubular necrosis
Peri-renal Pseudocyst
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Don’t diagnose with US!
US appearance secondary to
oxalate crystal deposition
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Medullary rim sign
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Encapsulated fluid around
kidney
Causes: ureteral obstruction,
trauma, neoplasia, infection
Sonographic appearance:
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Elliptical anechoic collection of
subcapsular fluid
Marked distant enhancement
Internal septa or mildly complex
Often kidney abnormalities
Specific “Diseases”
Peri-renal Pseudocyst
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Renal Pelvis and Ureters
Internal septation
Renal Pelvic Dilation
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Renal Pelvic Dilation
Recognize separation of
renal sinus by anechoic
space
Degree may be minimal
to advanced
Differentiate from renal
vein and normal medulla
DDx:
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diuresis, pyelonephritis,
obstruction of outflow,
congenital disease
Normal pelvis
Renal Pelvic Dilation
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Renal Pelvic Dilation
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Hydronephrosis:
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Most dramatic form of
dilation
dilation
of diverticulum
Mild to severe
Dilated anechoic renal pelvis
and recess with acoustic
enhancement
May only see thin rim of
cortex and oval dilation in
long standing cases
Pyelectasia
Always search for a cause!
Calculi in pelvis or ureters
Ureteral or bladder (trigone) mass
 Pyelonephritis
 Ectopic ureter
 Ureteritis
 Ureteral stricture
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dilation of pelvis
dilation of pelvis
Mild hydronephrosis
Calculi
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Calculi
Can see all calculi, although
may be better localized with
radiographs
Sonographic appearance:
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Hyperechoic focus with strong
acoustic shadowing
Shadowing depends upon size
of calculus, respect of calculus
to focal zone, frequency of
transducer
May see accompanying
distention
calculus
calculus
acoustic shadow
Calculi
Calculi
Acute ureteral obstruction due to calculus
Renal Pelvic Dilation
Bladder tumor leading to ureteral obstruction
pelvis
mass
ureter
Kidney transverse
Ureter longitudinal
Renal Pelvic Dilation
Ureteral infiltrate leading to ureteral obstruction
Renal Pelvic Dilation
Pyelonephritis
Ectopic ureter
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Acute form
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ureter
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Dilated pelvis (mild) and
proximal ureter
Paralleling hyperechoic line
+/- renomegaly
Hyperechoic cortex or
medulla, patchy hyper- or
hypoechoic areas
Poor CM differentiation
Severe hydronephrosis
Acute Pyelonephritis
Acute Pyelonephritis
Acute pyelonephritis with ureteral obstruction
- obstruction due to pus clot
Echogenic debris in dilated pelvis
Pyelonephritis
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Chronic Pyelonephritis
Chronic form
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Changes secondary to
fibrosis
Mild to mod dilation and
distortion of pelvis and
recesses
Proximal ureteral dilation
Often small and irregular
kidneys
Increased echogenicity with
poor CM
Distorted pelvis
Aspergillosis pyelonephritis
Pyelonephritis
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Excretory urogram
more sensitive for
pyelonephritis,
especially the
chronic form
Renal Pelvic Mass
Rare
 Differentials:
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dilated pelvis
Hematoma
 won’t
shadow like
calculus
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Tumor
 often
from renal
parenchyma
mass
US-guided renal sampling
Can you differentiate the following?
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May need sampling due to non-specific nature of
ultrasound findings
Fine-needle aspiration
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Relatively safe
Can sample cortex, medulla, pelvis
Core biospy
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US-guided renal sampling
More invasive
Requires heavy sedation or anesthesia
Only cortex sampled
US-guided renal sampling
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Can inject iodinated contrast into dilated
renal pelvis after sampling urine
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Ultrasound-guided percutaneous pyelogram
Renal FNA
Useful for:
 lymphoma
 carcinoma
 metastatic/disseminated
neoplasia
 FIP
 abscess
 fungal infection
 cyst
Renal Biopsy
Not useful for:
 congenital/hereditary
anomalies
 GN
 glomerulonephropathy
 interstitial nephritis
 amyloidosis
 PKD
 vascular abnormalities
 nephrocalcinosis
 multifocal renal
cystadenocarcinomas
Indications:
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Not indicated:
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Renal Biopsy
Contra-indications:
 Uncorrectable
coagulopathy
 Severe anemia
 Hydronephrosis
 Uncontrolled
hypertension
 Large or multiple cysts
 Peri-renal abscess
 Extensive
pyelonephritis
 End-stage renal
disease
Complications:
 AV fistula formation
 Cyst formation
 Hemorrhage
 Micro- and
macroscopic hematuria
 Peri- or intrarenal
hematoma
 Lacerated vessel
 Hydronephrosis
 Infarction and
thrombosis
 fibrosis
Doppler effect
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Apparent shift in sound
frequency as sound waves
reflected from moving blood
cells
Doppler shift: difference
between received and
transmitted frequencies
Spectral waveform
displayed on monitor
Have identified underlying cause of glomerular disease and
treatment leads to resolution of proteinuria
Chronic or end-stage renal failure
 Unlikely to alter prognosis, therapy, outcome
 Unlikely that cause will be determined
 Increased risk of complication
Renal Biopsy
Technique:
 16 or 18 gauge
 Cortex only
 Samples
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Glomerular disease – 2
quality samples
ARF – may only need 1
sample
Apply digital pressure for
5 minutes
Doppler Vascular Studies
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Consider when results are likely to alter patient management by
 providing histologic diagnosis or
 facilitating prognostication
Glomerular disease
Acute renal failure – persistently severe deterioration despite
appropriate medical management
Vaden SL. Renal biopsy: methods and
interpretations. Vet Clin Small Anim,
34:887-908, 2004.
Doppler Vascular Studies
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Can provide information in renal disease by
calculating the renal vascular resistance
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May be useful in ureteral obstruction, acute
renal failure, renal transplants, renal tumors
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(Dias freq – Peak Sys freq)/Peak Sys freq
Doppler Vascular Studies
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Doppler Vascular Studies
Normal RI < 0.70
Acute obstruction
1.5 yo MN DSH: mild azotemia, recurrent
UTI
Clinical Correlation
Other than mineral, are the
kidneys:
a. Normal
b. Small
c. Large
1.5 yo MN DSH: mild azotemia, recurrent
UTI
Based upon the US images, what is the likely
diagnosis?
a. Hydronephrosis
b. Lymphoma
c. Polycystic kidney disease
9 yo FS Springer: intermittent hematuria
treated with abx
Which kidney is abnormal?
a.Left
b.Right
9 yo FS Springer: intermittent hematuria
treated with abx
7 yo FS DMH: lethargy, enlarged abdomen
Based upon the US
image, what is the
most likely diagnosis?
a. Abscess
b. Cyst
c. Neoplasia
7 yo FS DMH: lethargy, enlarged abdomen
Based upon the ultrasound
image, what is the most likely
diagnosis?
a. Hydronephrosis
b. Neoplasia
c. Peri-renal pseudocyst
5 yo MN Schnauzer: hematuria
What is the likely cause of the
US findings?
a. polycystic kidney disease
b. pyelonephritis
c. ureteral obstruction