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!
What is the danger of using barium?
Large amounts can dehydrate and kill you!
If you do not see any evidence of free gas.
If you see a leak with barium, there is also GI leaking.
What do you do if you come across a patient and observe pneumomediastinum and you want to do a contrast study?
Only use barium if there is no mediastinal gas.
In the case with pneumomediastium, use isotonic, non-ionic iodide or refer!
What are the abnormalities you will see on an esophogram?
- Dilation (same as on survey rads)
- Constriction (esophagitis, intramural masses, extramural masses)
- Opacity (filling defects; foreign objects, granulomas, neoplasia)
- Function (peristalsis vs aperistalsis)
If you are looking for dilation of the esophagus..
You don’t need to do a contrast study, due to the risk of aspiration, instead you can see on radiographs.
Esophagram abnormalities:
Dilation:
Segmental (vascular ring)
**Persistent right 4th aortic arch (PRAA) is the most common.
Right subclavian anomaly
Double aortic arch
Others
Esophagram abnormalities:
Opacity (filling defects)
--Opacity (filling defects)-- Foreign objects Granulomas Neoplasia Gastoesophageal intussusception Hiatal hernia Food *cant tell the difference between
Esophagram abnormalities:
Function
Peristalsis vs aperistalsis
- Can observe if the esophagus is dilated.
- If not dilated, requires real time radiography
- -Fluoroscopy, display, monitor video recording, substitute (multiple serial images)
A foreign object in the stomach is an example of..
A natural negative contrast medium (increased opacity of the object).
Stomach has lots of natural contrast medium.
What is Pneumogastrography?
Used when you suspect an FB (object).
-Soda (pop) (lemon-lime) dosage prn as needed.
-Room air (10 ml/kg for a cat) and (20 ml/kg for a dog)
Radiographs (at least a lateral and a VD, should make all 4 views)
Upper GI (stomach and small intestine) contrast studies.. When will you perform? (3)
- Clinical signs with negative survey radiographs.
- Confirm suspected abnormalities on survey radiographs
- To outline size, shape or position of organs.
Upper GI (stomach and small intestine contrast studies.. Contrast agents?
**Barium sulfate suspensions (30%)
-8-12 mg/kg
**Organic iodides
Non-ionic isotonic compounds (iohexol); 10 ml/kg diluted 1:1 with water depending on the concentration.
Upper GI stomach and small intestine contrast studies..
Patient preparation for contrast studies?
- *Empty GI tract if at all possible! (contents alter the transit time, empty colon is important, food and feces produce filling defects)
- *Survey radiographs (may not need contrast, use for comparison)
- *Sedation if needed, Dogs; acepromazine and cats; ketamine/valium. Nervous or frightened patient can result in altered transit time.
What two drugs for dogs and cats has the least effect on bowel motility and GI dilation?
**Sedation if needed, Dogs; acepromazine and cats; ketamine/valium. Nervous or frightened patient can result in altered transit time.
How do you administer contrast agent to avoid less air?
Danger?
Administer with a stomach tube, but make sure the stomach tube is in the stomach!!!
Check tube before instilling barium to avoid barium in the lungs. Feel for two tubes, trachea and stomach tube. Add a few mls of water or saline.
How do you time the exposures in dogs with upper GI stomach and small intestine contrast studies?
Timing of exposures in dogs:
- VD, DV, and both laterals IMMEDIATELY after administration.
- Same views 15, 30, and 60 minutes later after administration.
- VD and lateral at hourly intervals until most of the barium is out of the colon.
- Immediately you will see the barium in the stomach, 15 minutes the stomach and most of the upper half of the small intestines, 30 minutes it left the stomach and it is all over the small intestines, by 2 hours you should see it in the colon.
How do you time the exposures in cats with upper GI stomach and small intestine contrast studies?
Timing of exposure variants;
Cats will go faster.
Iodides will go faster.
Need 4 views in early portion to evaluate the stomach due to the effect of gravity in the large “hallow” organ.
Psudeoulcers in dogs..
Normal architectural variations that maybe found.
Are actually peyers patches.
Bead-like segments in the GI of cats.
Segmentation is normal in cats.
What is the normal mucosal/contrast interface in the GI?
Should be smooth.
-May have fine fimbriated pattern in the dog.
-Normal peristalsis- smooth boarders (peristalses will change location during the exam, if not consider mass or foreign object).
Bowels should change location and appearance throughout the study, they should NOT be fixed!
What is a barium enema?
Double contrast, more informative.
Procedure: 24 hour fasting, soapy enemas.
Sedation or anesthesia.
Barium 10-15%, variable volume (~10 ml/kg)
Foley catheter + large syringe.
Distention of the colon.
**Hardly used today due to colonoscopy!
What are examples of urinary contrast studies?
Excretory Urogram Pneumocystogram Positive contrast cystogram Double contrast cystogram (puddle study) Urethrogram (looks for blockage or constriction) Vaginogram
What is an excretory urogram requires?
Visualization of contrast medium in the renal pelvis and ureter requires:
- Adequate renal blood flow
- Functional glomeruli to filter the medium
- Tubular resorption of water to concentrate the medium
- Patent collecting system.
What is an excretory urogram?
Visualization of contrast medium in the renal pelvis and ureter.
Inject metal opacity (iodine based) contrast agent into the bloodstream to be excreted by the kidneys to create an opacity interface with the inside of the urinary tract (kidneys, ureters and bladder).
Decreased excretion of a contrast medium during an excretory urogram can mean…
Urinary obstruction Damage of functional renal tissue Decreased renal blood flow Inadequate dose of the contrast medium Overhydration
***Can you assess renal function with an excretory urogram?
NO
It relies on renal function, but not an accurate assessment of function.
What is the contrast agent used with an excretory urogram?
Ionic agents are contra-indicated in dehydrated patients.
Iohexol (non-ionic) is more expensive, but a safer isotonic medium.
excretory urogram
contraindications?
- Anuria or clinical dehydration (hydroscope)
- Severe elevation in BUN and serum creatinine indicating renal failure.
- Dehydration, proteinuria
- Diabetes mellitus
- Heart failure
- Hypertension
- If you need to perform an excretory urogram on these patients you need to do a pre-med + assessment to avoid crash!
What are the 3 phases of an excretory urogram?
Vascular phase
Nephrogram (seeing kidney, out in the parenchyma)
Pyelogram
*20 minute compression help see the renal pelvis.
Nephrogram tends to fade, if it greats brighter that is a problem!
*Treat with fluids!
This type of cystography is most used, least useful..
Pneumocystogram
This type of cystography can assess bladder position and rupture.
Positive contrast cystogram
This type of cystography is also called a puddle study. Looks at bladder mucosa, looks for bladder masses and cystic calculi.
Double contrast cystogram.
How do you perform a cystography?
Empty the GI tract (causes interfering interfaces)
Place a catheter aseptically
Instill 2-5 ml of lidocaine
Withdraw as much urine as possible
5-10 ml/kg of 20% iodinated contrast medium (diluted with saline) slowly while palpating the bladder
-diseased bladder may not hold this much, may take more or less depending on the issue.
Make lateral and VD, oblique radiographs to see the os penis
-ruptured bladder may only require a lateral view
Remove contrast medium from the bladder.
How do you perform a double contrast study?
- 2-5 ml organic iodide contrast medium in an empty bladder.
- Then you fill the bladder with gas (CO2) (3-5 mls)
*Prep as with positive contrast and place the catheter.
Instill full strength contrast medium into empty bladder
Dog: 1-6 ml dose depending on size
Cat: 0.5 to 1 ml total dose
Distend the bladder with CO2 or room air
-5 to 10 ml/kg slowly white palpating the bladder.
-Diseased bladder may not hold this much.
Make left lateral and VD, and oblique radiographs
Remove gas and fluid from the bladder.
Why do you want to do a double contrast study of the bladder in left lateral recumbency?
To avoid systemic air embolization.
Where will you see gas bubbles in a double contrast study?
On the edge of the bladder
Where will you see calculi in a double contrast study?
In the middle
Where will you see blood clots in a double contrast study?
Float all over
Urethrography in a male canine
Pediatric Foley catheter - prefilled.
Balloon at the base of the os penis.
Inject 1-2 ml/kg- dilute (50/50)
Film at end injection, lateral and oblique.
Urethrography in a female canine
Place foley catheter just inside distal urethra
Inject contrast 0.5 to 1.0 ml/kg
Lateral and VD films at end injection.
Urethrography will find..
Dysuria Hematuria Trauma Uroliths Obstruction
What is the contrast study in the female highlighting the reproductive tract and the urinary tract?
Vaginourethrogram
*Contrast radiology lecture; slide 42
What is the contrast study that highlights the aorta and the heart?
Angiograph
Angiocardiography
*Contrast radiology lecture; slide 43
What is the contrast study of the spinal column?
Myelography
*Contrast radiology lecture; slide 44
What is the contrast study of the joint?
Arthrography
*Contrast radiology lecture; slide 45
What is the contrast study used to observe abscesses in a patient?
Fistulography
- Put contrast medium into the opening.
- On this image filling defect due to a foreign object.
*Contrast radiology lecture; slide 46
This technique involves injecting radio-opaque (positive) contrast medium through the punctum in the eye and the canliculus and making radiographs as the medium passes through the nasolacrimal system..
Dacryocystorhinography
seen in rabbits
Contrast studies are less popular due to the emergence of..
CT, ultrasound and MRI
Safer, easier and yield more information in most cases.
