Contrast Media Flashcards
what is contrast media
a compound used to enhance the contrast of a structure during medical imaging
what does the administration of oral and IV contrast do
aid distinction of the GI tract and vascular structures from other tissues
function of contrast - in the brain
contrast can enhance the tumour from the normal surrounding tissues in which it is located, thus improving the delineation of the gross tumour volume
this only applies to tumours of the brain
oral administration of contrast
used to visualise the GI tract
barium or water soluble gastrografin
rectally administered contrast
used to outline rectum
Intravenously administered contrast
used to visualise tumour mass, blood vessels and urinary system
Intravenously administered contrast
used to visualise tumour mass, blood vessels and urinary system
when is IV contrast used in oncology
to define the treatment area for RT planning
what are the contraindications for oral and rectal contrast
GI perforation
GI obstruction
Ulcerative colitis
Diverticulitis of GI tract
what are the contraindications to IV contrast
previous reaction to IV contrast
impaired renal function
certain diabetes drugs (Metformin)
how does a previous reaction to IV contrast effect the patient
increases the risk of a severe adverse reaction by a factor of 5
why is impaired renal function a contraindication to IV contrast
IV contrast is excreted through the kidneys and can impact on kidney function
what is used to assess patients renal function prior to administration of IV contrast
serum creatinine levels
what do creatinine levels in the blood show
how well your kidneys are functioning
what does estimated glomerular filtration rate (eGFR) do
it converts creatinine levels through a formula to an estimated rate of kidney function
other contraindications of IV contrast
multiple allergies pregnancy/lactation potential pulmonary effects - asthma liver failure blood clotting disorder multiple myeloma
what determines the volume of the contrast and the flow rate at which it is administered?
a MDT consultation
what is extravasion
the leakage of an intravenous drug from the vein into the surrounding tissue
what is an air embolus
a blood vessel blockage caused by one or more bubbles of air or other gases in the circulatory system
how do you prevent air embolism when administering IV contrast ?
ensure all air is expelled from the line prior to administration of IV contrast
what are the side effects of contrast injection to the patient?
- metallic taste in the mouth
- generalised hot/warm sensation in the body
- sensation that they have passed urine
what is the time frame for the greatest risk of reacting to IV contrast?
within first 5 minutes after administration
