Contrast Media

Question 1

what is the purpose of contrast media

Answer 1

To distinguish areas of anatomy during imaging

Question 2

Types of contrast media

Answer 2

iodine based, gadolinium, Barium sulphate

Question 3

which modalities use contrast?

Answer 3

CT, MRI, General Radiography, Fluoroscopy, Cath labs, Endoscopy

Question 4

How is contrast administered?

Answer 4

Injected, Orally and Rectally

Question 5

what happens to the contrast after the imaging ?

Answer 5

it is excreted via urine or bowel movements

Question 6

High risk groups for iodine based contrast

Answer 6

• Diabetic patients
• Patients with kidney disease (including renal transplants)
• Those who have had previous reactions to contrast
• any severe allergies
• dehydrated patient
• those who have received a large volume of contrast in the past 24 hrs

Question 7

measures that are put in place to reduce risks

Answer 7

• pre-scan blood tests (eGFR required. Potential Urea and Creatinine)
• pre-scan safety questionnaire
• keep contrast dosage as low as possible
• warming of the contrast

Question 8

Estimated glomerular filtration rate (eGFR)

Answer 8

This is a test to measure the level of kidney function

- calculated from the patient’s blood creatinine test, age, body size and gender

Question 9

eGFR values and administering contrast

Answer 9

eGFR > 60mls/min = patient can have contrast
eGFR between 30-60mls/min = needs further discussion
eGFR <30mls/min = patient should NOT have IV contrast

Question 10

pre-scan safety questionnaire

Answer 10

• Have you previously had iodine based contrast?
• Have you previously reacted to iodine based contrast?
• Do you have any drug/food allergies?
• Are you allergic to latex or plasters?
• Do you have diabetes?
• Do you take Metformin (if so must be stopped for 48hrs prior to the scan if eGFR is abnormal)
• Do you have asthma?
• Do you have kidney disease?
• Any previous heart attacks?
• Do you take any blood thinning medication?

Question 11

warming contrast

Answer 11

• contrast should be kept in a warmer prior to the scan- warmed to 37 degrees
• warming the liquid reduces the viscosity - which reduces the resistance within the vessel
• 10x less likely to induce a reaction in the patient

Question 12

adverse reactions to contrast (mild)

Answer 12

• nausea
• itching
• flushing
• minor skin rash

Question 13

adverse reactions to contrast (moderate)

Answer 13

• severe rash
• wheezing
• abnormal heart rhythm
• SOB
• abnormally high/low blood pressure

Question 14

adverse reactions to contrast (severe)

Answer 14

• swelling of throat
• difficulty breathing
• respiratory arrest
• convulsions (spasms causing jerky motions)
• cardiac arrest

Question 15

Extravasations

Answer 15

leakage of fluids (e.g. contrast) from a vein into the surrounding tissues.

Question 16

signs of Extravasation

Answer 16

• pain and tenderness
• swelling
• itching
• tightness of the skin
• redness

Question 17

steps to take after Extravasation

Answer 17

• discontinue the contrast injection
• raise the limb
• apply an ice pack
• inform the radiologist
• keep the patient under observation