Contrast media Flashcards
Name the 2 basic categories of CM
- Positive CM
- Negative CM
How do positive CM appear on an x-ray film and why?
- Positive CM contains elements with a high atomic number.
- These are radio-opaque.
- They appear white on an x-ray film.
How do negative CM appear on an x-ray film and why?
- Negative CM are gases with low density.
- These are radiolucent.
- They appear black on an x-ray film.
Name 2 examples of positive CM
- Barium
- Water Soluble Iodine
Name 4 gases commonly used for negative CM
- Room air
- O2
- CO2
- N2O
What is a double contrast radiograph?
It is when negative CM and positive CM are both used to view a specific area
What is used in a double contrast gastrogram?
Positive CM barium is used to line the stomach and then distended with Negative CM air
What is used in a double contrast cystogram?
Positive CM iodine is used to line the bladder and then distended with Negative CM air
What forms can barium come in?
- powder
- paste
- solution
What are the advantages of Barium?
- inert
- insoluble
What is a disadvantage of Barium?
May cause foreign body reaction if it leaks from GI tract
When should Barium NOT be used in the GI tract?
Do not use if there is a GI rupture as it will cause reaction in peritoneum and could be fatal
Name a brand of water soluble iodine
- Conray
- Gastro-conray
- Urografin
- Gastrografin
- Hypaque
How is water soluble iodine excreted if administered IV?
Via the kidneys
Name 2 places water soluble iodine can be used as a CM.
- The lower urinary tract
- The GI tract (not as good as barium)
When should water soluble iodine be used instead of barium for a GI tract CM?
If there is a GI rupture
Water soluble iodine is ………… - tonic.
Hyper
List 4 side effects of water soluble iodine
- fall in blood pressure (if IV)
- anaphylactic reaction (if IV)
- whining (if conscious)
- retching (if conscious)
Give an example of a brand of Lower Osmolar Ionic Media
Hexabrix
What done ionic mean?
contains salts
What is not suitable for a myelogram and why?
- Lower osmolar ionic solution
- Because it’s a salt solution therefore draws water in to the cisterna magna causing pressure to build up in the area.
List 2 advantages of Lower Osmolar ionic media
- Fewer side effects than water soluble iodine
- Better contrast in GI tract than water soluble iodine
What CM is suitable for a myelogram?
Lower osmolar non-ionic media
Give an example of lower osmolar non-ionic media brand name
Omnipaque
What does non-ionic mean?
does not contain salts
What is lower osmolar non-ionic media especially safe for and why?
Myelography because there’s no salt so no water is drawn in to the costerna magna and pressure remains safe.
What should be carried out before doing a myelogram?
Normal x-rays
Why perform a myelogram?
To indicate lesions that are not detectable on ordinary x-rays
Why would myeography be indicated?
- spinal pain
- neurological signs
- prolapsed intervertebral disks
What method of restraint should be carried out for a myelogram?
General anaesthetic
How would the patient be prepared and what equipment would be needed for myelography?
- Patient anaesthetised
- Clip relevent area
- Surgical scrub of patients skin
- Patient head elevated
- Spinal needle selected (size depends on size of patient)
- Correct dose of appropriate contrast media (warmed)
- Syringe
- Sample bottle for CSF
- Vet should scrub up as if for sterile surgery and don sterile gloves
Why should the head be elevated during myelography?
Convulsions can occur if the head is not elevated
Where would the spinal needle be placed for a myelogram?
- Most commonly the Cisterna Magna
- Less commonly the Lumbar
Explain the Cisterna Magna puncture method.
- Tilt the table to 10°
- Clip and surgically clean site
- Head flexed to 90° of spine
- VS inserts needle between skull and atlas vertibra
- Needle advanced slowly until CSF drips out of hub (needle is in cisterna magna now)
- Take CSF sample for cytology
- Inject warm CM slowly over 1 min
- Patient must remain completely still during procedure
- Head extended once needle removed
- radiographs of both lateral views and VD once lesion identified
- Head remains elevated until completely recovered
What should be kept to hand during myelography?
- Crash box
- Diazepam in case of seizure
The patient should always have an ……… ………………. placed and be well …………………. prior to CM.
The patient should always have an IV Catheter placed and be well hydrated prior to CM.
What drug should NOT be given prior to myelography and why?
ACP - lowers seizure threshold
When can reactions occur due to the CM?
They could happen straight away or be delayed.
Why would an Upper Gastrointestinal Study be carried out?
To evaluate the stomach and small intestines (But CM can be used to study the oesophagus right through to the anus.)
What would indicate an upper gastrointestinal study?
- vomiting
- abnormal bowel movements
- suspected foreign body or obstruction
- chronic weight loss
- persistent abdominal pain
How would the CM media be administered for a upper gastrointestinal study?
Orally using syringe if patient willing to swallow or a stomach tube if not.
What CM would be used in a upper gastrointestinal study?
- Barium sulphate normally used (positive CM)
- Water soluble iodine if perforation suspected (positive CM)
- Positive and Negative CM can be used if stomach is the target
List the equipment needed to do a upper gastrointestinal study.
- Stomach tube
- Large syringe (catheter tip preferrably)
- Contrast Media
- Lubricant
How long should a patient be fasted prior to a upper gastrointestinal study?
Fast for 24 hours prior to upper gastrointestinal study.
When should enemas be performed prior to the upper gastrointestinal study?
- 24 hours before
- 4 hours before
- 1 hour before
What drugs are suggested for upper gastrointestinal study and why?
- ACP = sedative
- Glucagon = gastrointestinal hypotonic agent that induces gastric hypomotility
- GA = slows gut
- Atropine = slows gut
How can you ensure the orogastric tube is placed correctly?
Inject small amount of water in to tube. If patient coughs then tube is incorrectly placed in the trachea. Tube should be re-placed.
What intervals should radiographs be taken at after CM administered for upper gastrointestinal study?
- immediately after CM administration
- 15 mins
- 30 mins
- 60 mins
- 90 mins
What types of radiographs should be taken after CM administration for upper gastrointestinal study?
- DV
- VD
- R. Lat
- L. Lat
What is the dose rate for water soluble iodine used in a upper gastrointestinal study?
1ml/1lb
What are the indications for a cystogram?
- haematuria
- dysuria
- infection
- bladder rupture
- anuria
- calculi
What are the precautions for a cystogram?
- palpate bladder while administering CM so as not to rupture or over-distend
- place patient in left lateral recumbency to administer CM to reduce risk of air embolism
List the equipment needed for a cystogram
- urinary catheter
- 3 way tap
- syringes
- sterile lubricant
- skin prep solution
- gauze
- 2% lidocaine
- sterile gloves
- otoscope speculum
- kidney dish
- water soluble iodine
What is the patient prep for a cystogram?
- fasted for 12-24 hours
- enema 4 hours prior to exam
- abdo images should be taken prior to sedating/anaesthetising the patient
- sedate/anaesthetise patient
How is a cystogram performed?
- take R. lat and VD radiographs of abdomen
- external area cleaned with appropriate solution
- apply sterile lubricant to catheter
- insert catheter aseptically
- empty as much urine as possible
- administer 3-5ml of 2% lidocaine in to bladder (less for feline patients)
- L. lat recumbency for CM administration
- bladder held as air administered to prevent over distension
- slowly administer water soluble iodine and roll patient 360° to coat mucosa with CM
- take L.lat, VD and oblique radiographs of bladder
