chapter 12 contrast agents Flashcards
to distinguish adjacent tissues on a CT image the tissues must have different
densities (attenuation)
CT has 2 main contrast enhancements
intravscular and gastrointestinal
when the contrast agent is of higher density it is refereed to as
positive agent
when the contrast agent is of a lower density
negative agent
contrast has an atomic number of
53
2 tissues must differ by at least ___Hounsfield units to be visibly iffernt on a Ct scan
10
most intravascular drugs are nearly
isotonic
isotonic
have nearly the same number of particles in a solution per unit liquid of blood
osmolaity
refers to the number of particles in solution ,per unit liquid, as compared to blood
high osmolaity
have seven times the osmolaity of blood
low osmolaity
have 2 times the osmolaity of blood
the osmolaity of blood plasma is
290 mOsm/kg water
viscosity
is a physical property that may be described as the thickness or friction of the fluid
half life on contrast
2 hours
contrast does not metabolize and is excreted by the body nearly exclusively by the kidneys through
glomerular filtration
the most common formula for calculating the dose og contrast for peds
2mL/kg
less than ___ of the dose of contrast agent given to the mother is excreted into breast milk
1%
contrast reactions can be broadly categorized as
chemotoxic or idoiosyncratic
when steroid premedication is used it must be given _____before contrast
6 hours
chemotoxic
reactions that stem from the contrast pharamacologic properties
the overall kidney function is described as
clearance
clearance
the volume of plasma that is cleared of a specific substance in a given time
normal adult GFR
120 mL/ min
normal ERPF
500 ml/min
