Contrast Media

Question 1

What is Contrast Media?

Answer 1

A substance administered to a patient that is either more radiolucent or opaque than the surrounding tissues

Administered to enhance radiographic contrast within a system or organ to enable differentiation of surrounding structures

Question 2

What is a plain radiograph?

Answer 2

Soft tissue structures & organs are difficult to identify & indistinguishable from each other due to their similar tissue opacity resulting in a lack of contrast

Question 3

Administer contrast media

Answer 3

Soft tissue structures & organs are identifiable due to the increase in radiographic contrast

Question 4

What are the 3 types of contrast media?

Answer 4

Positive contrast media, negative contrast media, double contrast media

Question 5

What is positive contrast media?

Answer 5

• Agents containing elements of high atomic number & increased density
• Highly radiopaque
• White appearance on a radiograph
• Provide positive contrast with soft tissues

Shows up as white due to the high atomic number, high specific gravity & high density of the contrast agent

Question 6

What is negative contrast media?

Answer 6

• Gases
• Black appearance on a radiograph
• Highly radiolucent
• Provide negative contrast with the surrounding tissue

Pneumocystogram: shows up as black due to the low atomic number, low specific gravity & low density of the contrast agent

Question 7

What is a double contrast media?

Answer 7

Negative & positive contrast agents are used in combination

Most commonly used to perform studies on hollow organs such as the bladder as it provides optimal mucosal detail

Question 8

Ideal properties of contrast media

Answer 8

Non-toxic
Non-irritant
Inert (lacks the power to move)
Cost effective
Provide optimum contrast to the surrounding tissues
Be eliminated from the body

Question 9

What are the 4 categories of contrast media?

Answer 9

1. negative contrast agents
2. barium preparations
3. Iodine Preparations - Ionic Water-soluble iodine based media (hyperosmolar)
4. Iodine Preparations - Non-ionic Water-soluble iodine based media (low osmolar)

Question 10

What are negative contrast agents?

Answer 10

Most common agent is room air
May use oxygen, co2 & nitrous oxide

Question 11

What are barium preparations?

Answer 11

Barium sulphate is positive contrast medium & used solely for alimentary tract studies
Insoluble agents
Not diluted by alimentary secretions & not absorbed & digested by the intestines

Question 12

What are Iodine Preparations - Ionic Water-soluble iodine based media (hyperosmolar)?

Answer 12

Used for a wide range of studies (mainly CV & urinary)
High osmotic pressure (x8 that of normal body fluid)
Side effects include brain & nervous tissue damage
Examples include Conray & Urografin

Question 13

What are Iodine Preparations - Non-ionic Water-soluble iodine based media (low osmolar)?

Answer 13

Similar to ionic but much lower osmotic pressure making them safer for myelography. Fewer allergic reactions
Can be used for other studies (CV & urinary) & when IWSIBM is contradicted
More expensive than ionic media
Examples include Omnipaque & Niopam