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U of M CVM 6104 - Special Procedures in Veterinary Radiology - Urogenital

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1Special Procedures in Veterinary Radiology--UrogenitalTravis C. Saveraid, DVM, DACVRAssistant Clinical ProfessorCollege of Veterinary Medicine –University of MinnesotaRoentgen Signs•Margin• Opacity• Size • Shape•Number • Location2Urogenital Contrast Procedures• Intravenous Pyelogram (IVP); a.k.a. Intravenous Urogram (IVU), Excretory Urogram (EU)• Cystography (positive, negative, double)• Urethrography (retrograde, normograde)• VaginographyIVPIVP-indications• Identification / characterization of kidneys and ureters• Ectopic ureters• Suspected renal or ureteral calculi• Identification of enhancement voids in renal parenchyma• Rough estimate of renal function3IVP-indications• Abnormal renal size/shape on survey radiographs or palpation• Inability to identify kidney(s) on palpation or radiographs• Identify filling defects in renal pelvis / ureters• Hematuria without lower urinary tract signs• Suspected ureter ruptureIVP-indications• Incontinence• Assess involvement of kidney/ureter in adjacent disease processes (e.g. neoplasia in bladder trigone)• Suspected pyelonephritis4Renal PelvisDiverticulumUreterIVP-contraindications• DEHYDRATION• Allergy to Iodine• Heart failure• Renal failure/azotemia are NOT contraindications but will affect the quality of the study5IVP-complications• Vomiting• Hemodynamic effects (hypotension, hypervolemia)• Contrast medium induced renal failure• Allergic reaction to contrast (hives, anaphylaxis)• Non-diagnostic studyIVP-materials• Enema materials• Contrast agent— iodinated (ionic fine for most patients, consider using non-ionic for azotemic or critical patients• IV catheter – typically cephalic veinIVP-materials• Compression band? - Vetrap• Fluoroscopy unit – if available• Crash kit– Fluids– Endotracheal tube– Drugs (epinephrine, steroids, antihistamines, dopamine)6IVP-preparations• Fast 12-24 Hours, enemas as needed to clear colon • Survey radiographs to establish technique, assess preparation, and check for changes since last radiographs• Sedation or anesthesia can be helpful in some patientsNon-prepared abdomen.Prepared Abdomen7Collect Urine for Urinanalysisbefore IVP• Most contrast will increase urine specific gravity for up to 24 hours following IVP• Some contrast medium inhibits growth of urinary pathogens• If urine not collected before IVP, collect urine at least 24 hours after procedure.IVP-procedure• Details vary from reference to reference and radiologist to radiologist• Basic principles– Adequate dose for opacification of tract– Adequate timing to assess functional questions– Adequate views to assess anatomic questions (e.g. obliques for ureter termination)IVP-procedure• Typical dose 800-900 mg I/kg body weight–Most ionic agents are 350-400 mg I/ml, so 1 ml/lb (Omnipaque is 240 mg I/ml)– Maximum volume 90ml– Dose may be increased 1.5 to 2 X for azotemic patients to compensate for poor uptake– Inject as a bolus through catheter – Helps to warm contrast (less viscous)8IVP-procedure• Ventrodorsal view at time 0• VD and lateral views at 5, 10, 20 and 40 minutes• Oblique lateral views (or fluoro) at 5 minutes to assess termination of distal ureters IVP-options• Compression band is referred to in some references– Tight bandage around caudal abdomen– Increases distension of pelvis and proximal ureters– Yields little additional information and carries small riskIVP-options• Concurrent negative cystogram – Urethral catheter placed, bladder distended with gas (room air o.k. in most situations, NO2or CO2in cases of hematuria)– Provides improved contrast with the ureters as they enter the trigone– Helpful for suspected ectopic ureters9IVP-options• “Paddle” views– Radiolucent paddle (e.g. wooden spoon) gently applied to abdomen during exposure to displace organs– Particularly useful to displace intestines away from kidneys and bladder– Less useful in large, blocky patients– May need to decrease technique (thinner)Bladder Stones?Yes – Look closely!10IVP-normal findings• Three phases– Angiogram phase: all blood vessels opacify, very brief (usually miss it), not too relevant in our patients– Nephrogram phase: kidneys are actively concentrating iodine, persists to some degree throughout study. Early phase cortex brighter than medulla, later enhancement is uniform– Pyelogram phase: pelvis and ureters enhanceSurveyAngiography phase to early Nephrogram phaseIVP-normal findings• Uniform, symmetric renal enhancement• Opacity of kidneys fades over time• Size (on VD view)– Dog: 2.5-3.5 x L2– Cat: 2.4(1.9?)-3.0 x L2• Shape elongated, may be flattened on lateral view (cats slightly rounded)11IVP-normal findings• Without abdominal compression, renal pelvis and pelvic recesses approximately 2mm or less• Pelvis and recesses sharply marginated• Proximal ureter generally less than 2.5 mm• Visibility of ureters is variable due to peristalsisIVP-normalIVP-normal12IVP-normal findings• Ureters course medially on VD, dorsally on lateral from renal pelvis• Ureters often superimposed on spine on VD, each other on lateral• Ureters terminate at trigone dorsally, with a hook• Bladder gradually fills with contrast IVP-normal findingsIVP-abnormal findings• Enhancement timing– Never– Poor, fading– Poor, persistent– Poor, increasing– Fair-good, fading (normal)– Fair-good, persistent– Fair-good, increasing13IVP-no enhancement• Renal absence (agenesis, excision)• No blood flow (infarcted, transected, ligated, avulsed)• Nonfunctional (may get vascular blush)• Contrast dose too low, too slow or wrong place (extravascular, connectors popped loose)Unilateral enhancement14IVP-Poor, fading• Any cause of polyuricrenal failure• Contrast dose too low or too slowIVP-poor, persistent• Chronic glomerulardysfunction• Non-specific generalized renal diseaseIVP-poor, increasing• Acute obstruction• Hypotension• Ischemia15IVP-good, persistent• Acute tubular necrosis• Contrast medium-induced renal failure• Hypotension post-contrastIVP-good, increasing• Hypotension post contrast• Acute obstruction• Contrast medium-induced renal failureIVP-abnormal findings• Enhancement pattern– Uniform (normal)– Focally non-uniform– Multifocally non-uniform– Absent16IVP-focal• NAG (neoplasia, abscess, granuloma)• Cyst• InfarctIVP-focalIVP-multifocal• NAGs

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