Contrast radiography Flashcards
What is contras radiography
the use of contrast medium to improve radiographic contrast between soft tissue structures
contrast study improves the visualization of:
1) shape, size,location
2) mucosal skeleton
3) luminal contents
4) organ function in some cases
What is Positive Contrast Agents and what color do they appear on radiographs
are used to fill or outline a hollow organ
they appear white (are radiopaque to x-rays)
give examples of positive contrast agents and what route are they administered (4)
barium- po or emema
gastrografin- po or emema
oral hypaque- po or emema
renografin -IV or urinary catheter
what is an angiography
contrast study of the blood vessels
what is contrast urography
contrast study of the urinary system
What is contrast medium
a substance that is either radiolucent or radiopaque that can be administered to an animal to increase radiographic contrast within an organ or organ system
Water-soluble iodine preparation
tir-iodinated compounds supplies as sodium or meglumine salts of iothalamic or metrizoic acids, or a mixture of both
name the 6 characteristics of water soluble iodine contrast
1) radiopaque
2) pharmacological inert
3) low in viscosity
4) low in toxicity
5) rapid renal excretion
6) chemically stable
name the 3 indications for water-soluble iodine contrast
1) administer IV to visualize the vasculature and or the excretory system
2) administer for UGI or LGI if G.I. perforation is suspected
3) administer via urinary catheter for cystography
name 2 contraindications for water-soluble iodine contrast
1) not suitable for myelography or arthrography
2) the rapid transit time through the GI tract and dilution of the agent while it is passing through the GI tract (does not produce as much contrast)
what is the preferred contrast agent to use for GI studies
Barium
when should you not use barium and why?
if perforation is suspected- it does not get absorbed
what could happen if you use water-soluble iodine contrast for myelography or arthrography studies
causes tissue irritation and inflammation when one of these agents is injected into the subarachnoid space (may cause seizure) or into a synovial joint space (cause arthritis)
name possible side effects of water-soluble iodine contrast agents (6)
Mild discomfort and nausea (MOST COMMON) dehydration local tissue irritation (causing inflammation) hypovolemia and shock (RARE) cardiac arrest (RARE) allergic reaction (mild-to severe)
what is anaphylaxis
an acute allergic reaction to an antigen to which the body has become hypersensitive
treatment epinephrine
name 3 Characteristics of of low osmolar contrast agents
nonionic (no salt compound)
fewer side effects
suitable for myelography or arthrography
name 3 examples of low osmolar contrast agents
mettixamide
iopamidol
iohexol
Name 2 characteristics of barium sulfate
insoluble in water
liquid, paste, or powder
name some indications for a GI contrast using Barium
persistent diarrhea or vomiting, regurgitation, dysphagia, intestinal obstruction, chronic weight loss, persistent abdominal pain, abnormal bowel movements, intussusception, rectal mass, abdominal mass, and intestinal stricture
what happens if barium leaks into the abdominal cavity, and if it does, what do you do
produces severe peritonitis with high mortality
surgically flushed out within 6-8 hours
name the 5 negative agents
room air CO2 nitrogen nitrous oxide O2
name 3 properties/ uses of negative agents
used for negative contrast studies
are radiolucent
admin via stomach tube or urinary cath
why do you need to use caution when using room air as a negative contrast agent
may cause air embolism in the bloodstream
explain double contrast study
both a positive and negative agents are used
best for viewing mucosal detail
how long should the patient go without food before a study
12-24 hr
how far in advance do you need to perform an enema before a contrast study
2-4 hours
if the patient cant be NPO before the study, what can you do to minimize the presence of food in the GI tract
feed low granular food (ex baby food or AD)
what sedation is ok to use for contrast studies of the GI tract and why
Phenothiazine tranquilizers (Acepromazine) -minimal effect of peristalsis
Why is atropine contraindicated
slows down peristalsis
anticholinergic effect
name 4 side effects of soluble agents administered IV
vomiting
hypotension
allergic reaction
dehydration
