Contrast Studies Flashcards
What are the common contrast studies used?
*Gastrointestinal studies
*Myelography- the spinal canal
*Urinary tract studies
*Cystography- helping diagnosing problems in bladder
*Urography- urinary tract studies
*Arthrography- creating a picture inside a joint
What are the types of water iodine soluble preparation techniques?
conventional water soluble iodine +/- contrast
non ionic low osmolar iodine
negative contrast media
double contrast
What are the features of conventional water-soluble iodine +/- contrast?
ionic salt- high pressure
licensed for i/v and p/o administration
anaphylaxis possible- hypotensive used for GI tract studies when perforation suspected
NOT USED IN MYELOGRAPHY- toxic to tissues
What are the features of non ionic low osmolar iodine?
safer, can be used in myelography- low osmotic pressure
suitable for all studied but EXPENSIVE
can be used instead of barium in gut studies
What are the features of negative contrast media?
low anatomic number, absorption of x-rays
radiolucent appears black, poor mucosal detailing
air
carbon dioxide
oxygen
What are the features of double contrast?
negative and positive contrast used together, bladder GI,
small amount-
positive contrast agent used to coat inner lining of organ, distended using negative contrast agent e.g. air
Provides excellent mucosal detail
How does positive contrast appear?
white. radiopaque
How does negative contrast appear?
black, radiolucent
What is barium sulphate atomic number
56
When should barium sulphate NOT be given?
if perforation is suspected
Define Density
degree of blackening film, determined by exposure used and processing tech
Define Contrast
difference between radiographic densities (shades of grey)- on radiograph
Define Definition
sharpness/ clarity of the structures, visible on radiographs
Overexposure-
can rescale image through grey-scale, areas with lowest density BLACK
Underexposure-
images appear grainy, insufficient photons reaching detectors-
unable to differentiate between background electronic noise and low signal created by x-ray photons
REDUCED CONTRAST
