Urinary Tract Imaging- Basic
Principles
Campbell’s Chapter 4
Christi Hughart, D.O.
Plain Films
• Scout film, primary survey, to follow known
stones, check placement of
catheters/stents/drains/foreign bodies
• False +: vascular calcifications, bowel opacities,
phleboliths, appendicoliths, GS
• False -: stone over sacrum/ilium, radiolucent (uric
acid)
• If scout before ESWL shows no stone, may need
to reassess
Plain FilmLeft Distal Ureteral Calculus
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Contrast Films
• Rapidly concentrated by kidneys and opacifies
urinary tract
• Low osmolar nonionic contrast material (LOCM)50% less osmolar load- fewer complications than
high osmolar
• Reactions: dose related or idiosyncratic
– Allergic, CV changes, renal toxicity, shock
– Tx- antihistamines, beta agonist, epinephrine
– Renal toxicity risk (average patient)- 1%
• Direct toxicity to renal tubules, ischemia, altered circulation,
precipitation of uric acid
• Prevention- well hydrated, LOCM, small load
IV Urography
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Renal parenchyma, collecting system, ureter
Evaluates- urothelial abnormality, hematuria, urolithiasis
+/- bowel prep/npo
Scout, +/- obliques
Contrast- bolus or drip
Nephrographic phase- immediate to first minutes- parenchyma
Pyelographic phase- 5 minutes- collecting system
– +/- compression, oblique- calyces, prone to distend ureter, uprightrenal ptosis/layering in severe hydro, post-void- evaluate
BOO/diverticulae/filling defect
Normal Urogram
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Urogram with Prone Filmbetter visualization of ureters
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Loopography
• Imaging of urinary conduit or diversion (always order with indication
clearly explained)
• Reflux required to see ureters if no IV contrast used (constrast
sensitivity not contraindication)
• If non-refluxing anastamosis- need IVU, antegrade nephrostomy, CT,
MRI
• Indications- hematuria, stones, stoma stenosis, loop ischemia, urinary
fistulae, urine leak, stricture at anastamosis, hydro, tansitional cell
cancer surveillance
• Prep- bowel prep if previous contrast, antibiotics, GU irrigant
• Contrast goes in thru catheter
• Scout, supine, conduit distension, drainage film
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Static Cystourethrography
• Evaluate bladder lesion, rupture, leak, s/p
trauma/sx- bladder integrity/anast/fistulas
• Scout, fill bladder with 200-400 mL contrast
via catheter, A/P and obliques (shows
extravasation posterior to bladder), postdrainage film
Voiding Cystourethrogram
(VCUG)
• Functional and anatomic evaluation of bladder
• Typically for children with recurrent UTIs
• Dx- reflux, urethral valves, ureterocele, dysfunctional voiding, urethral
strictures, bladder/urethral diverticula
• Scout
• Pediatric: 5 or 8 F feeding tube, fill bladder with contrast (age +2 x
30)
• Adult: standard catheter
• Film during filling- bladder pathology, early reflux
• Films during void- reflux, urethral abnormality
• Oblique- evaluate grade 1 reflux, males
• Post-void film
Normal Male Cystogram
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VCUG
Retrograde Urethrogram (RUG)
• Evaluate anterior and posterior urethrastrictures, trauma
• 8-16 F foley in fossa navicularis, fill
balloon with 1-2 mL and inject 30-50%
contrast while filming obliquely
• Some resistance at membranous urethra and
sphincter
Normal RUG
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Retrograde Pyelography
• Evaluate renal collecting system and ureters
• Indications- hematuria, contrast sensitivity, suboptimal
IVU, needs cysto
• Pre-op- get sterile urine culture
• IV sedation
• Scout, injection catheter placed in UO, inject 50% contrast
under real time fluoro, drainage film at 5-10 minutes
• Backflow- contrast extravasation into surrounding tissues
due to high injection pressure
Normal RP
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Nephrostogram
• Antegrade urogram- inject contrast into
nephrostomy tube
• Indications- post-sx to evaluate for urine
leak, post-perc neph to evaluate residual
stones, evaluate site of ureter obstruction,
dx ureteral fistulas
• Prep- sterile urine sample, +/- antibiotics
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Ultrasound
Grayscale and doppler
High frequency- high resolution but low penetration depth
Renal- parenchyma, solid vs cystic, hydro
– Use with IVP to evaluate hematuria
– Assess allografts, congenital abnormalities, stones
– Cortex vs medulla- pyramids (medulla) less echogenic than cortex
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Adrenal- CT/MRI better except in peds (no RP fat)
– Nodules, cysts, hemorrhage, location, tumors
– Cortex hypoechoic, medulla echogenic
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Bladder- examine wall, lesions
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Transvaginal, transabdominal, transrectal
Normal wall >= 6 mm
Echogenicity in bladder fluid- debri, FB, infection
PVR, bladder volume
Ureteral jets- should appear in 15 minutes unless obstruction exists
Prostate- transrectal, access for biopsy
Ultrasound (cont.)
• Scrotal– Use high frequency probe (up to 10 MHz)
– Evaluate- mass, pain, torsion, orchitis, epididymitis, hydrocele,
hernia, varicoceles
– Testicle- granular, 4 x 3 cm, small anterior fluid collectiontunica, epididymis- hyperechoic
– Veins- >2mm= varicocele- evaluate in erect position with valsalva
• Urethral– Male- evaluate stricture- scar length and depth, longitudinal along
phallus or intraluminal
– Female- diverticulum
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CT
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Contrast- parenchyma, adrenals
3-D or CTA- evaluate vascular abnormality
100-150 mL IV bolus injection
Renal– Precontrast- stones, parenchyma, vascular
calcifications, renal contour
– Corticomedullary- 30 sec- cortex vs medulla
– Nephrographic- 100 sec- uniform enhancement of
parencyma (masses)
– Pyelographic- excretory- collecting system
– Left renal vein- anterior to aorta, inf/post to SMA
– Right renal vein- extends posterolateral from IVC
CT (cont.)
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Adrenal– Malignancy, mets, functional adenoma
– Adenoma- HU <0
– HU >20- ? Mets- do perc bx
– MRI if suspect pheo
Bladder– Depends on amount of distension
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Prostate/seminal vesicle– To detect abscess or cyst
– If prominent median lobe- appears to extend into bladder
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CT urography– Enhanced CT of ureters
CTA
• Rapid contrast injection with helical CT
during arterial phase
• Soft tissue and bone reduced
• 3D reconstruction
• Indications- prep for donor nephrectomy,
eval extra vessels to eval UPJ obstruction,
renal artery stenosis
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MRI
• No iodinated contrast
• Soft tissue resolution better than CT
• Contraindications- pacer, aneurysm clips, FB,
prosthesis
• Allignment of protons in response to external
magnet- radiofrequency applied causes difference
in their energy
• T1- fluid dark, fat bright
• T2- fluid bright, fat dark
MRI (cont.)
• Renal- do if need cross-sectional images but contrast contraindicated,
will not evaluate stones, determine tumor thrombus in IVC, cortex
bright on T1
• Adrenal- adenomas contain more fat than cancers/pheos, pheo bright
on T2, gland seen easily on T1, T2- adrenals isodense with liver
• Bladder- to id invasion of wall by transitional cell cancer or other
pelvic neoplasms (on T2)
• Prostate- evaluate prostate cancer for capsular invasion. T1-distinct
from surrounding fat/seminal vesicles (intermediate intensity), T2peripheral zone (high intensity), central (intermediate), neurovascular
bundles bright, seminal vesicles (high)
• Urethral- intraluminal coil to evaluate stricture/diverticulum
• MRU- to id obstruction- ureters/collecting system- T2- fluid bright,
tissue dark (can’t distinguish stone from clot/tumor)
MRA
• Gadolinium
• Indications- abdominal aorta, ranal artery
stenosis, pre-donor nephrectomy
Nuclear Scintigraphy
• Physiologic and anatomic info
• TC-99 m (t ½= 6 hrs)
• MAG3- cleared by tubular secretion, no
glomerular infiltration- evaluate renal function and
renal plasma flow
• DTPA- glomerular filtration- evaluate obstruction
and renal function
• DMSA- cleared by filtration and secretion- renal
cortical image
Diuretic Scintigraphy
• For hydro not necessarily caused by
obstruction
• Done with DTPA or MAG3 (better for renal
insufficiency)
• When tracer reaches collecting system,
diuretic given and t ½ calculated based on
slope of curve given in response to diuretic
Renal Cortical Scintigraphy
• DMSA to evaluate for cortical scars or
pyelo
• Do 3 months after infection