Flashcards in Contrast media Deck (60):
what organs display a low amount of subject contrast? (6)
stomach, kidney, liver, spleen, pancreas, and bowel
what is subject contrast?
is the radiographic contrast caused by the difference in the composition of the patients body tissues
what is subject contrast caused by?
the tissue differences, the anatomic number differences and the thickness of the patients body parts
what 3 organ systems display a low subject contrast?
digestive, urinary and cerebrovascular
what parts of the stomach and intenstine can you see on plain films?
fundus of the stomach due to the gastric bubble and any part in the large intestine that has fecal matter or gas
what is contrast media?
are diagnostic agents that are introduces into the body orifices or injected into the vascular system, joints and ducts to enhance subject contrast in anatomic areas where low subject contrast exists
what does the contrast media depend on? (2)
the anatomic number of the element used in a particular medium and the concentration of atoms of the element per volume of medium
what are the 3 types of contrast media?
1. radiolucent (negative) contrast agents
2. radiopaque (positive) contrast agents
3. speciality contrast agents
what are the MRI contrast agents?
gadolinium diethylenetrianminepentaacetic acid (DTPA)--metalic and magnetic agent that affects signal intensity
how do ultrasound enhance subject contrast?
gas filled microcmubbles that affect the sound wave to enhance ultrasound contrast
what are the physical properties of negative contrast agents?
-composed of elements with low atomic numbers and decrease the attenuation of the x-ray beam
negative contrasts can be administered by 2 way?
gas (air) and carbon dioxide (tablets, crystals, soda water)
what kind of density does the negative contrast agents produce?
increased density, as more x-rays reach the film the structure that is filled with negative contrast agents appear black on the radiograph
what kind of air is the most common negative contrast agent?
room ari- the air in the lungs serve as a negative contrast medium on the chest radiograph
what is a double contrast effect?
when a negative agent may be combined with a positive contrast agent
what kind of agent is barium?
positive contrast agent
what kind of contrast agent must never been injected intravenously? why?
negative, can cause serious or fatal affects
what are positive contrast agents composed of?
elements with high atomic numbers
how do positive contrast agents appear on a radiograph?
absorb more x-rays and appear bright
how much more x-rays do positive agents absorb than bone? soft tissue?
bone about 3 times, and 5 times more than soft tissue
what are 2 types of positive contrast agents?
barium (56) & iodine (53)
what is the atomic number of barium?
what is the atomic number of iodine?
what is the atomic number of soft tissue?
what is the atomic number of gadolinium?
2 types of iodinated compounds?
water soluble and oil based
what is barium sulfate used for?
inert power composed of crystals that is used for examination of digestive system
what is the chemical equation for barium?
BaSO4- one atom of barium to one atom of sulfur to 4 atoms of oxygen
the mixture of barium and water forms?
colloidal suspension--never dissolves in water
what is flocculation?
when powder clumps and come out of suspension
what are used to prevent flocculation?
what are the stabilizing agents?
sodium carbonate and sodium citrate
what does enteral mean?
within, or by way of, the intestine or gastrointestinal tract
why can't barium be used intravascularly or intrathecally
because of its inability to be absorbed by the body
what is intrathecal?
introduced into or occurring in the space under the arachnoid membrane of the spinal cord or brain
what are the adverse reactions of barium? (6)
barium in the appendix, sedated patient, allergic reactions, hypervolemia, vaginal rupture, extravasation, and obstruction/constipation
what is extravasation?
leakage from a vessel into the tissue
what can extravasation lead to?
who is prone to extravasation after barium?
elderly, long term steroid patients, patients with diverticulitis and ulcerative colitis
what is a vaginal rupture?
rare complication of barium sulfate administration, it is due to the misplacement of the catheter before lower GI examinations--you should ask female patients if they feel enema tip in the rectum
what is hypervolemia?
a blood disorder consisting of an increase in the volume of circulating blood --this can occur when water from the cleansing enema or barium enema is shift from the colon to the circulatory system resulting increase blood volume
what are the consequences of hypervolemia?
edema, seizures, coma or death
what is added to barium by manufacturer to reduce the possibility of hypervolemia
what atomic number does iodine have?
what would oiled based contrasts be used for?
lymphangiograms and bronchograms
what were oil based contrast used for in the past?
myelograms, bronchograms, hysterosalpingograms, sialograms and dacryocystograms
what has replaced oil based contrasts
water soluble iodinated contrast media
what kind oil based or water soluble should not be injected intravenously?
oil based- not miscible with blood
what is miscible?
capable of being mixed together
what are oil based medias made from?
what is a two carbon atom chemical group called
what is viscous?
of a liquid, not pouring freely, having the consistency of syrup or honey
what is insoluble?
not soluble, unable to dissolve
what is the main disadvantage of oil based iodine?
they persist in the body because they are water soluble
what is anaphylactic shock?
is the result of an exaggerated hypersensitivity reaction to an antigen that was previously encountered by the body immune system
what is the most common cause of anaphylaxis ?
iodinated contrast agents
water soluble contrast may be described as either?
ionic iodinated contrast media or nonionic iodinated contrast media
what long does it take the body (kidneys) to excrete the water soluble contrast?
What is osmolslity
Refers to the concentration or number of particles in the solution per kg of water and is directly related to the occurrence of adverse reactions