Contrast Media Flashcards
Why is contrast media used?
-to visualise soft tissues
How does contrast media work?
-reduced affect so x-ray beam hits soft tissues differently
-addresses the lack of contrast by selectively absorbing more x-ray photons than the soft tissues
Where is contrast media absorbed?
-into the body to increase the contrast or structures of liquids
How does contrast media exit the body?
Excreted from the body
Where can contrast media be introduced into?
Blood vessels
Visceral
Cavities
Joints
What is negative contrast media?
-has a very low physical density
-radiolucennt (appears black)
-used to define location of viscus rather than anatomical detail
What are examples of negative contrast media?
Room air
Carbon dioxide
Oxygen
What is positive contrast media?
-high atomic number and attenuate the x-ray beam more with viscus, organs and vacates
-radipaque (appears whiter than bone)
What are examples of positive contrast media?
Barium
Iodine
When is barium used?
Only for gastrointestinal studies
What are advantages of using barium?
Insoluble
Inert (moves slowly)
Has therapeutic effects
What are disadvantages of using barium?
May cause foreign body reaction if leaks
Constipation
What are the different ways of giving barium, and when each is used?
Suspension - swallowing and oesophageal cases or GI tract
Paste - pharyngeal and oesophagus
Powders - not commonly used due to them building up
When is iodine used as a contrast media?
Intravascular studies (GI tract)
Lower urinary tract studies
Joints
Salivary glands
Lacrimal sac and ducts
What are advantages of using iodine?
Water soluble
Excreted by the kidneys
What are disadvantages of using iodine?
Difficult to administer as is not palatable
Can cause fall in blood pressure
Cannot be used when conscious
Shows poor contrast for bowel
How should ionic iodine contrast be given?
Should be warmed to body temp prior to use
Is viscous
When should ionic iodine contrast be used?
Cardiovascular
Urinary tract
Why is non-ionic iodine contrast used?
Less allergic reactions
More expensive
Shaper contrast bordered for an increased time
What are the 5 methods of contrast radiography?
Gastrogram
Myelography
Retrograde urethrography
IV urography
Cystogram
What does myelography indicate?
Lesions that are not detectable on ordinary x-ray
When is myelography used?
Spinal pain
Neurological signs
Prolapsed invertebrate discs
What are methods of myelography?
Cisterns magna puncture
Lumbar puncture
**GA is essential
What contrast media is used for upper gastrointestinal study and how is it administered?
Barium sulphate
Orally administered using a stomach tube
What patient preparation is required for upper gastrointestinal studies?
Fast for 12-24 hours
Cleansing enema 24hrs prior before and 3 and 1 hr before
X-rays taken 1hr after procedure
What radiographs are taken for upper gastric study and when are they taken?
Dorso-ventral
Right lateral
Left lateral
Immediately after administration
Taken at 15, 30, 60, 90 mins intervals
What contrast media is used for double cystography?
Air or gas
Water soluble ionic or non-ionic agents
What patient prep is required for double cystography?
Fasted 12-24hrs
Enema at least 4hrs prior to exam m
Abdominal images taken prior to sedation
What contrast media is used for pneumocystography?
Gas or air
Such as carbon dioxide
What special precautions are taken when administering contrast for pneumocystography?
Patient positioned in left lateral recumbency to administer gas to reduce the risk of an air embolism
Palpate bladder whilst administering gas to prevent rupture
What patient prep is required for pneumocystography?
Fast for 12-24 hrs
Enema at least 4hrs prior to exam
Abdominal images taken prior to sedation
What is the procedure of a pneumocystography?
R lateral and VD views of abdomen
Insert catheter and empty bladder
Plain radiograph taken before contrast
Administer 2% lidocaine into bladder
Place in L lateral and administer gas
Take views of bladder with contrast
When is double contrast used?
On hollow organs such as stomach or bladder
Both positive and negative contrast media is utilised
Used on cystogram and gastrogram
What equipment required for GI blockage?
Barium solution
Stomach tube
Syringe
X-day machine
Barium used as not absorbed too quickly
What equipment required for GI perforation?
Iodine
Stomach tube
Syringe
X-ray machine
Iodine as will be absorbed quickly
Should the air be removed after contrast media study?
Must be removed
What equipment is required for double cystogram?
Sedation
Iodine solution
Air (oxygen)
Catheter
Lube
Syringe
