Contrast studies Flashcards
Contrast radiography
Taking of radiographs using a contrast media
Enables the visualisation of internal organs and structures, where contrast is low
changes the density of the specific structures of interest.
Uses
On plain radiographs two organs of similar densities cannot be distinguished between
Uses
Contrast studies aim to render these structures and organs more visible and to outline the mucosal surface where appropriate
it does this by changing the radiopacity of the structure or that of the surrounding tissues. Ie. The contrast
Uses
The most common contrast studies seen in practice include:
Gastrointestinal studies - xray exams that examine your GI tract
Myleography - a diagnostic imaging test generally done by a radiologist
urinary tract studies - diagnosis of UTIs is primarily made by the presence of typical symptoms
Arthrography - a type of imaging test used too look at a joint, such as the shoulder, knee or hip
cystography - a procedure used to visualise the urinary bladder
urography - imaging and contrast material to evaluate or detect blood in urine, kidney or bladder stones and cancer in urinary tract.
Properties of Contrast Media
Contrast medias should be:
Easy to administer
-Non - toxic
- Non - irritant
- Provide optimum contrast to surrounding tissues
Positive contrast media - Barium Sulphate
-High atomic number
- Absorb large proportions of x-ray beam
-Radiopaque
Barium sulphate
white chalky material
used for GIT studies not for injection into blood vessels
Positive contrast media - Barium
Used for barium swallows and meals
does not react with acid in the stomach
unable to use in anaesthetized patients - can’t swallow
Non - toxic and well tolerated by patient
insoluble - not diluted by body fluids so maintains contrast along length of the gut
do not give if perforation is suspected
BIPs
Barium impregnated polyethene spheres
- fed to patient - large or small capsules
- gelatine capsule containing the sphere of barium
- safer as less likely to leak if perforated gut
- passed in feaces
Barium Enema
24 hour pre-procedure starve
Enema
Rectal catheter placed
Barium runs into colon until backflow
- can follow with double contrast using air
- Barium drains out into enema bag
- bag lower than patient - gravity
- compress bag gently - air at top reflates colon
Conventional water soluble iodine +/ve contrast
ionic salt - high osmotic pressure.
Liscenced for I/v and P/O administration
Anaphylaxis is a possibility - What do you need to consider before induction
Nausea and retching likely if given to conscious patient
Excreted by the kidneys outlining the upper urinary tract
Used for GIT studies when perforation suspected. Contradicated in shock/dehydration cases - osmotic pressure drawing fluid out of system
Non Ionic Low Osmolar Iodine
Much safer contrast media
Can be used for myelography as they have much less affect on sensitive nervous tissue
suitable for use in all studies but much more expensive
can be used instead of barium in gut studies if perforation is a possibility
Negative Contrast Media
- Low atomic number
- low absorption of x rays beam
- Radiolucent appears black on x-ray
poor mucosal detailing
Air
Carbon dioxide
Oxygen
Double contrast
negative and positive contrast media are used together
usually in the bladder / GIT
a small amount of positive contrast agaent is used to coat the inner lining of the organ, which is then distended using negative contrast agent
provides excellent mucosal detail
Use of contrast
POM-V
checks should be made and SOPs should be followed
- date and type of contrast
-Quantity and concentration required
-correct route of administration
-warm the contrast medium - check for foreign particules
- aseptic porcedures
-record type and amount given on patient record
-Nursing considerations specific to procedure
