Contrast Media Flashcards
Define attenuation
Reduction of the intensity ( number of photons
Photons get absorbed or scatter
Define radiolucent
Objects that easily allow x rays to pass through ( lung tissue)
Define radiopaque
Objects that’s do not allow X-rays to pass through easily (hip prosthesis)
Define differential absorption
Objects are demonstrated on a image when they absorb different amounts of X-rays than surrounding structures
What do contrast agents do?
They change the absorption of structures so they are visible/ create differential absorption
Define positive contrast media
Increase absorption
-barium (56 protons )
-iodine ( 53 protons)
Radiopaque
Has high attenuation (shows up bright)
Define negative contract’s agents
Decreases absorption (dark area on images)
-gases
-air
-co2
Radiolucent
Low attenuation
Define barium
-Barium sulfate is a heavy metal
- preferred contrast for most GI studies
- Not for parenteral use
- only for enteral (GI) use
-liquid suspension mixture
What is iodinated contrast media (gastroview)
Free Iodine (I2) is toxic and good for killing germs
Define ionic ICM
-Has a charge
-Water soluble iodine
-Has a high osmolar contrast media (HOCM) (very salty)
- frequent contrast reactions due to high osmolarity
-used for non vascular studies
Define non ionic ICM
-Low osmolar contrast media (LOCM)
-only ICM that is IV injectable
- fewer reactions
-used for vascular and non vascular studies
Define monomeric ICM
-monomer
- 3 iodine/mol
- LOCM
- Isovue & omnipaque
Define dimeric IMC
-Dimer
-6 iodine/ mol ( more iodine w/ less molecules
- IOCM ( iso osmolar contrast media)
- visipaque ( vascular studies )
Define viscosity ICM
-LOCM & IOCM have significant viscosity
- warming contrast to body temp reduced viscosity
-slow to inject
Define osmolarity
- based on the number of particles in a solution
-HOCM adds lots of particles (salt water) - blood is very sensitive to osmolar and ion changes
- higher concentrations are usually more hypertonic
Discuss absorption characteristics
-Barium cannot be absorbed into bloodstream
-ICM can be absorbed from GI tract, intrathecal space, & peritoneal cavity
Discuss distribution characteristics
IV injection ( LOCM/HOCM)
Goes where the blood goes
In the kidney within 1 min
In the bladder and ureters within 3 mins
Discuss elimination characteristics
IV injections (LOCM/IOCM)
Cleared via kidneys
90+% passed In urine
Discuss indications, actions, & effects
Indications: for xray/ CT exams
Actions: absorbs x rays
Effects: enhances visualization of structures by increasing differential absorption
What factors influence dosage
Exam
Pt size
Concentration
Physician preference or mood
Pt condition
What is found in contrast media labels for MRI
It contains Gadolinium
It influences magnetic field during MRI scan
Bright in T1 MR images
What is the osmolarity of blood
290
Can you inject Ionic ICM?
no
used for non-vascular studies only (GI,Cystograms)
What are some Ionic HOCM
Gastroview
Gastografin
Cystografin
