1. Special Procedures
RVT: Chapter 25

2. Special Procedures: Learning Objectives
Understand the differences between types of contrast media
Understand the appropriate patient preparation for contrast studies
Know procedures & protocols for various studies

3. Special Procedures: General Principles
Contrast media is used to cause a difference in density and organ visibility
2 types of contrast media:
____________-contrast: Appears white or radiopaque
____________-contrast: Appears dark or radiolucent
Contrast agents are used in 2 ways:
Demonstrate anatomy by outlining or filling
Demonstrate physiology via excretion through an organ

4. Special Procedures: General Principles
_________ radiographs should be performed before contrast procedures
Injected contrast substance should be harmless to patient
Higher kVps typically needed in contrast studies
Ultrasound & other imaging techniques have replaced contrast radiography in many evaluations

5. Positive-Contrast Media
Barium sulfate
Used to radiograph the GI tract
Delineates mucosal walls well
Not absorbed in intestines
Administer orally or ____________
Low cost & palatable
*Cautions:
Cannot be used if a gastrointestinal perforation is suspected
Aspiration in lung can be fatal

6. Barium Aspiration: Lungs

7. Positive-Contrast Media
2. Organic Iodides
Use for suspected GI perforation/ obstruction
Water soluble
Intravenous or injected into body cavities
Non-irritating if aspirated or leaked into body cavities
2 types: ionic and ____________
Used for functional studies as well
Mixes with blood/body fluids & is excreted via the kidneys
More expensive than barium

8. Negative & Double-Contrast Media
Negative-contrast media:
Low atomic number or low-density agents
Air, nitrous oxide, oxygen, and carbon dioxide
Absorb fewer x-rays than soft tissue
Less mucosal detail with negative vs positive-contrast
Double-contrast procedures:
Use both positive & negative agents
Normally used to image the urinary bladder, stomach, or colon

9. Negative Contrast

10. GI Tract Studies Patient preparation: Evaluate: Contraindications:
Fasting + a cathartic or enema
Take survey rads prior to administration of contrast
Take required number of radiographs for study
4 views generally needed
Evaluate:
Organ size, shape, mucosal lining defects
Luminal contents (masses/foreign bodies)
GI transit time and blockages
Contraindications:
Distended stomach
Gastric torsion
Gastric perforation

11. GI Tract Studies Contrast agents: Barium suspension is most common
It’s a suspension…
Given via syringe, orogastric tube, feeding tube
Spilling barium on the fur will cause a radiographic artifact
Do not get barium on the radiograph equipment!

12. Esophagography
Contrast radiography of the esophagus to identify lesions
Evaluates morphological or structural alterations
Uses a paste of positive contrast media
Indications:
Dysphagia
Regurgitation, gagging, or retching
Megaesophagus
Abnormal swallowing
Esophageal dysfunction
Foreign bodies
*Fluoroscopy may be better

13. Esophagography Precautions: Patient preparation: Comments:
Patients with dysphagia are at risk for aspiration
Contrast may not be needed if esophagus is fluid or food-filled
Patient will remain awake for procdure
Patient preparation:
If evaluating megaesophagus – empty prior to administration
Can mix barium with canned food to thicken it
Comments:
Avoid barium artifacts!

14. Megaesophagus

15. Upper GI Study
Barium is given orally, then images are taken during transit through stomach and small bowel
Studies can be done for:
Morphology – Form & structure of organs
Size, shape, and position or organs
Character of stomach wall & contents
Lesions in the GI tract
Function – How organ works
Gastric motility
Intestinal function
Indications:
Any GI irregularities (vomiting, diarrhea, anorexia, weight loss, etc.)
Inconclusive results of survey radiograph

16. Upper GI Study Precautions: Patient preparation:
For suspected perforation or rupture, use iodides
Ultrasonography may be preferred
Delay study if full stomach
Gastric distention is not recommended immediately after gastric surgery
Patient preparation:
GI tract should be empty – fast at least 12 hours prior
Administer enema 2-4 hours prior
If using orogastric tube - verify placement in esophagus
Before removing, clear with small amount of air and kink to prevent aspiration

17. Upper GI Study Procedure: Comments & tips: Administer barium (slowly)
Take 4 radiographs centering over cranial abdomen
Both VD and lateral views
Label films carefully!!
Comments & tips:
If slow GI emptying is suspected, start study early in the day
Give a sufficient volume of barium
Gastrogram is finished when the majority of barium is no longer visible in the stomach
Upper GI is complete when the barium is in the colon

18. Barium Upper GI Study: Dog
15 minutes
30 minutes
60 minutes
(Stomach, duodenum)
(Stomach, duodenum, jejunum)

19. Lower GI Study Used for examination of the cecum, colon, and rectum
Evaluates for masses and lesions
Full distention with removal of feces is required
Retrograde administration of barium may be required
Cathartic & warm water enemas the night before
Fast for hours (water allowed until 4 hours prior)
Sedation is usually warranted
Endoscopy may be preferred

20. Lower GI Study (barium)

21. BIPS Barium-impregnated polyurethane spheres
A way to quantify gastric emptying (motility and transit time)
Dosage is number of large & small spheres
Gastric emptying rate is calculated based on number in areas of GI tract
Avoid drugs that reduce GI motility!

22. Urinary System Contrast Studies
Evaluate: Kidneys, ureter, bladder, urethra, and prostate
Sedated/anesthetized patient is preferred
Before administration:
Fast/enema given to patient
Collect any samples
Empty bladder
Three main types:
1. Excretory urography
2. Retrograde cystography
3. Urethrography

23. Excretory Urography (IVP)
Asses size, shape, and function of the kidneys and bladder
Commonly paired with ultrasound
IV iodinated contrast media
Place IVC and check patency
Solution should be clear and colorless
Bottle must be discarded the same day
Kidney will concentrate and then excrete the iodine
Iodine is what is providing the contrast on film
Contraindication: _____________

24. Excretory Urography Begin x-raying patient immediately after bolus!
Multiple views needed
__________ lateral abdominal radiograph separates kidneys better
Media will be in the bladder within 20 mins
*Why might you see contrast in the liver?

25. Retrograde Cystography
Infusion of contrast media into bladder through the urethra
Given via urinary catheter
Supplies needed:
Positive or negative contrast can be used
If hematuria- use negative
CO2 or nitrous oxide best due to solubility
Paired with IVP commonly
Ok to use is suspect bladder rupture

26. Urethrography Placing positive or negative contrast in the urethra
Evaluate urethra due to abnormal passage of urine
Can be a retrograde urethrogram or voiding urethrogram
Retrograde- usually male dogs
Voiding- easier; common to perform after cystography

27. Myelography Injection of contrast media into the subarachnoid space
Evaluation of the spinal cord
What is found in this space?
Can tell size of lesions or amount of spinal cord compression
Anesthesia required
Aseptic prep, usually in the cervical or lumbar region
CT and MRI are replacing this technique

29. Links to Case Studies
Barium Study in a Dog (Virtuavet) /26/barium-study-in-a-dog/
8-Year Old Curly-Coat Retriever Takes a Long Road to a Simple Answer (Virtuavet)-
“Titus”