1, 2 Contrast agents

Question 1

What are radiocontrast media?

List the positive and negative contrast

Answer 1

X-ray contrast agents.
Positive:
Iodinated ionic and non-ionic media
Non-iodine based media, Barium Sulfate (barium sulfate enemas)

Negative:
Air or carbon dioxide gas (negative x-ray contrast is basically just used during the double contrast barium enema)

Question 2

What is the osmolarity of ionic and non-ionic radiocontrast agents

Answer 2

ionic, above 1000 mOsm.

non-ionic, iso or hyposmolar (isosmolar is 290mOsm)

Question 3

What are hepatotropic contrast medias

Answer 3

Contrast agents that are excreted by the liver, and can image the bilary system.

Question 4

What are the oily contrast medias?

Answer 4

They are used for chemoembolization of some tumors.

Question 5

Non-iodinated contrast media

Answer 5

Most common one is Barium Sulphate
Used orally or rectally.

Not for IV, water insoluble, and will cause peritonitis or mediastinitis if it leaks out of the GI tract via a perforation. Contraindicated in any suspected/potential perf.
If it is aspirated it causes pneumonitis.

Question 6

What are the ionic and non ionic based media

Answer 6

Iodine based agents. Water soluble.
Are classified as ionic or non-ionic.

Ionics are excreted by the kidney, and have more nephrotoxic side effects. So, they are NOT used by IV, but are used for bowel contrast.

Non-ionic medias are also kidney excreted by have fewer side effects and are used for IV.

Question 7

MRI contrast agents

Answer 7

Alter the local magnetic field.

Paramagnetic contrast agents- Shorten T1 relaxation time -
Chelated Gadolinium agents.
Used for IV.

Superparamagnetic contrast agents- Shorten the T2 relaxation time -
Manganese chelates, Iron salts.
Used as oral contrast medium for GI imaging.

Question 8

Ultrasound contrast agents

Answer 8

Gas filled microbubbles that increase the echogeneicity of blood or whatever chamber they are in.

Cause the fluid to be hyperechoic, brighter/whiter on the US.