Contrast Media Flashcards
define contrast media
substances that increase radiographic contrast in an area of typically low contrast
what are the 2 types of contrast media
radiolucent/negative agents - appear black on image - air, CO2
radiopaque/positive agents- appear white on image - contrast agents
describe iodine agents
best contrast agents
can be administered orally or via IV
describe barium agents
aka barium suphate used for GI tract orally and rectal administration possible not absorbed significantly by GI can cause GI side effects - drink water
define non ionic vs ionic
non - remains whole (isnt broken down)
ionic - creates 2 ions in blood
define osmolality
the ability of a liquid to give up or take on water from another liquid separated by a semipermeable membrane
for contrast media what osmolality do we want? high or low?
low - specifically isomolar as that is the same as blood
what are the 2 types of contrast solutions used by CCMB
visipaque (IV)
telebrix (oral)
describe visipaque
intravenous
nonionic
iodine content -320mg/ml
osmolality - 290 (isomolar)
describe telebrix
orally taken
ionic solution
iodine content - 768mg/ml
osmolality - 2100 (high)
list some types of non-injected contrast
oral
rectal
cystogram - inbladder
cervix - tampon soaked with contrast
define viscosity
the thickness or resistance to flow of a liquid
what does viscosity have to do with injection rate
higher viscosity = slower injection rate (due to resistance)
fyi - heat can improve viscosity (easier to inject = low)
is IV contrast metabolized
nope
how is IV contrast excreted
filtered through kidneys excreted via urine
why are power injectors necessary
scan times are short and contrast can move through blood quickly
therefore constant administration is needed
it is very difficult to administer manually due to viscosity
what are the risks of power inectors
extravasion and air emboli
what are the symptoms of extravasion
pain, swelling @ injection site
what are some ways to prevent extravasion
feel injection site after initial injection
keep canulla minimum 20G
what are some symptoms of air emboli
stroke
usually undetected tho and get absorbed quickly
what is a way we can prevent air emboli
inspect tubing for air bubles
what vein is commonly used for power injector, why is it used
vein of antecubital fossa - cephalic and basilic
large and easily palpable
** can accept the pressure of the power injector
list 3 venipuncture equipment
catheter - soft, pliable with blunt end, attached to hub
stylet - AKA trocar, metal, with beveled tip + flash back chamber to fit inside catheter
protective cap - covers catheter and hub
what is the main implication of contrast media with tx planning
sims imaging involves a 1:1 ratio between CT numbers and density
therefore by administering contrast this ratio is not true
this creates a level of uncertainty when it comes to the path of the photon beam through the structures
