MRAD 2410: Module 3 (P3: Contrast Media)

how does positive contrast media appear on a radiograph

white

does positive contrast media absorb radiation

yes

how does negative contrast media appear on a radiograph

black

does negative contrast media absorb radiation

no

define osmolarity of contrast media

the concentration of iodine particles per 1 kg of water

when contrast agents with varying osmolarity enter the blood, how does it affect the pt

pt may experience changes in blood volume, BP, and CO

T or F: higher iodine concentration = high osmolarity

true

define viscosity

thickness of a suspension

T or F: highly viscous = harder to inject

true

higher viscous = harder to inject. what does this feel like for the pt

burning or stinging as it travels through blood vessels

higher concentration of iodine = higher or lower viscosity

higher

what makes a mixture toxic

it disagrees with the pts metabolism and chemical balance

T or F: toxicity is the major factor in determining the likelihood of an adverse effect occurring to a pt

true

solid contrast media is found in what forms

pill, granule

role of solid contrast media

produce gas that allow the stomach to expand

why do we want the stomach to expand during an exam

permits double contrast exam to occur (pt will ingest barium after ingesting the gas-producing pills)

describe the role of Iocetamic acid (aka Cholebrine)

solid contrast media that makes the gallbladder opaque

common gas contrast media

room air, CO2

what type of exam are gas contrast medias used in

double contrast exams; stomach, barium enemas, arthrography (joints), myelography (spine)

what are the requirements for medical gas contrast

most be non-toxic, absorbable by the body, and last long enough for the exam

why is CO2 preferred over nitrogen for gas contrast media

nitrogen absorbs more slowly

what type of gas contrast media is used in ultrasound

microbubbles: tiny injectable gas bubbles

role of microbubbles in ultrasound

provide vascular contrast by being detectable in the bloodstream

uses of microbubbles as gas contrast media

monitor chemo response, detect liver/kidney masses, identify cardiac pathologies, assess blood perfusion

list the two major classes of liquid contrast media

iodinated, non-iodinated

why do we use iodine specifically as a contrast media

high atomic number that is greater than most body structures = differential photoelectric absorption = good image contrast. also iodine’s k shell binding energy is similar to the average energy of xrays = photoelectric absorption is more likely to occur = good contrast

contraindications of iodinated contrast media

previous severe reaction, angioedema, bronchospasms, renal failure

when is high osmolarity contrast media used

used for GI and GU exams where barium sulphate isn’t feasible

when is barium sulphate not feasible

query perforation, stenosis, hemorrhage, GI fistulas, megacolon

how is HOCM administered

orally, rectally

why do we like low osmolarity contrast media

closer to the osmolarity of human serum = not as toxic

how is LOCM administered

intravenously, intrathecally

what is iso-osmolar contrast media used for

IV contrast media injections

what is non-water soluble contrast media used for

limited use: sclerotherapy, hysterisalpinography

what is the most common non-iodinated contrast media

barium sulphate

how is barium sulphate administered

orally, rectally

when do we use barium sulphate

GI exams with fluoro

why do we use barium specifically

high atomic number = high attenuation of xrays, cannot be absorbed by the GI system = non toxic

what forms do we use barium in

powder, tablet, paste, liquid

optimal barium viscosity for upper GI exams

both thick and thin

optimal barium viscosity for lower GI exams

thick

what does barium do to the GI system

coats it = visualization of GI lining

contraindications of barium

suspected GI perforation, risk of aspiration

possible complications of barium

peritonitis if an unknown perforation is present, plugging of distal airway due to aspiration