Contrast Radiology Flashcards
What is contrast radiography?
Introduction of a substance to create opacity interfaces where none exist
What type of contrast radiology can be used in the bladder?
Urine in the bladder can be replaced with gas (negative contrast) or positive contrast material (barium).
How can positive contrast material be used in the kidneys?
Positive contrast medium injected into the veins to be excreted by the kidneys to demonstrate the excretory urinary system.
Positive contrast medium can be injected into the arteries…
To replace blood.
Angiogram.
What contrast can be used in the stomach/bowel?
Gas or barium to interface with the mucosa.
Negative contrast materials?
Gas (air, CO2, O2, nitrous, ect).
Less opaque.
What is the concern with negative contrast medium?
Air embolism
What is the natural contrast medium of the bowel and lung?
Gas (air) is a natural contrast medium.
What are positive contrast medium materials?
Barium (paste, powder, suspension)
Organic iodide (water based)
*Oil based organic iodide is rarely used today.
Organic iodide
Ionic
Used as a positive contrast medium.
Ionic: diatrizoate and iothalamate
*Benzene ring, tri-iodated.
Original iodides, ionic media are typically hypertonic.
Dehydrated patient will have fluid sucked out of the patient, negative effect, separate and form different bonds (dissociation).
They come apart in the blood stream and fuse with other ions to form different compounds (organic chemistry)
Organic iodide
Non-ionic
NON-ionic: iopamidol *Benzene ring, tri-iodated. NEWER Safer Provide longer opacification Much more expensive. Non-ionic contrasts do NOT dissociate.
The use of ionic salts..
IONIC SALTS ARE NOT USED ANYMORE. (some say it is malpractice to use ionic salts) -Diatrizoate (Urografin, angiografin) -Iothalamate (Conray) -Metrizoate (Isopaque)
Two examples of non-ionic iodide used in practice?
Most commonly used:
Iohexol
Iopamidol
What are two organ systems that would use barium compounds for a positive contrast study?
Gastrointestinal and possible cystogram.
When would you use non-ionic organic iodides?
Myelograph (do NOT use ionic) Vascular Urography and Cystography Fistulograms GI if concerned about barium (non-ionic) CT contrast (diluted low dose of non-ionic)
GI contrast studies
Esophagram use of..
Barium swallow
*Gastrography (stomach and small intestine) also
GI contrast studies..
Colonograph uses..
Barium enema
Contrast studies in the GI have been largely replaced by..
Ultrasonography and endoscopy.
What can confuse the diagnosis of GI tract when using contrast radiology?
Motility present (peristaltic waves)
Once is an accident, twice a coincidence, three times is probably real!
*If present on three films its probably a lesion.
*Take enough films to be confident.
It is a balance between the “QUALITY” (confidence level) of a lesion and the number of times seen.
Esophagram
Contrast medium of barium is always used.
-Paste is thick and tenacious.
-Coats the mucosa, will show ulcerations and small irregularities (esophagitis)
Liquid barium (more volume)
Mixed with food (handling solids, obstruction)
How do you administer barium to a patient for an esophagram?
Administer in the cheek pouch and hope they swallow it. Paste works well on the roof of the mouth (like peanut butter).
X-ray immediately and hope you can catch it (multiple x-rays).
+/- ventrodorsal and oblique views for stomach and bowel.
+ fluoroscopy
What is fluoroscopy?
Real time imaging to see movement. If you can use, you have to take several images to see the bolus go down.
What are normal findings associated with an esophagram?
No significant retention.
Dogs: longitudinal folds.
Cats: longitudinal cranially, then oblique folds caudally.
-Herringbone pattern*
What are normal findings associated with an esophagram in dogs?
Longitudinal folds
No retention
What are normal findings associated with an esophagram in cats?
Cats: longitudinal cranially, then oblique folds caudally.
- Herringbone pattern*
- No retention
What is the contrast medium used for a liquid esophagram?
Barium Liquid
30-60% W/V
-Oropharyngeal and esophageal motility.
-Esophageal position and patency (general)
-15 to 30 ml as needed depending on the size of the patient.
What is the contrast medium used for a liquid PLUS food esophagram?
(soft food or kibble)
oropharyngeal and esophageal motility (with solid food)
esophageal patency (stricture)
What material do you want to avoid using in an esophagogram?
Avoid barium sulfate (USP)
What contrast medium should you use if you suspect a perforation?
Large perforations: contrast is generally not needed.
Very rarely will ID the location of the perforation.
Fear* of barium with possible perforation:
-Small amounts of barium no worse then food.
-Hypertonic ionic iodides are useless for small perforations (dilutes therefore easy to miss the lesions, causes pulmonary edema if aspirated)
What contrast medium should you use if you suspect a perforation?
Can use what if there is no mediastinal gas?
You can use barium if there is no mediastinal gas.
BETTER CHOICE: use of isotonic iodide (iohexol) -NON-ionic!