Special Procedures RVT: Chapter 25

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

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

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

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

Barium Aspiration: Lungs

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

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

Negative Contrast

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

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!

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

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!

Megaesophagus

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

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

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

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

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 24-36 hours (water allowed until 4 hours prior) Sedation is usually warranted Endoscopy may be preferred

Lower GI Study (barium)

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!

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

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: _____________

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?

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

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

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

Links to Case Studies Barium Study in a Dog (Virtuavet)- http://virtuavet.wordpress.com/2010/ 10/26/barium-study-in-a-dog/ 8-Year Old Curly-Coat Retriever Takes a Long Road to a Simple Answer (Virtuavet)- http://virtuavet.wordpress.com/2010/03/28/8-year-old-curly-coat-retriever-takes-a-long-road-to-a-simple-answer/ “Titus”