week 1: contrast media

Question 1

what are the two types of contrast?

Answer 1

1) positive
- barium, iodine
- give white appearance (absorb more X-rays)

2) Negative
- Air, gas
- Gives black appearance (allows more x-rays through)

Question 2

What is subject contrast

Answer 2

If structures have same density and atomic number then there will be no subject contrast.

therefore if there is a great difference in atomic number and density there will be a high amount of subject contrast.

subject contrast can therefor be artificial changed by adding contrast medias

Question 3

What are the requirements of Positive contrast medium

Answer 3

e.g barium, iodine

• Water soluble (won’t block arteries)
• Non-toxic
• High atomic number (e.g iodine=53)

Question 4

What happens to contrast in brain for normal person

Answer 4

Blood brain barriers work to hold in contrast within parenchyma.

if contrast enters parenchyma indicative of tumour

Question 5

what are variables that exist between iodinated contrast mediums

Answer 5

1) Ionic/ non ionic relative to blood
2) strength/ concentration
- Determines radiopaque. (high= better, but dangerous)
3) visocity
4) osmolarity
5) chemotoxicity. (ionic=more effects)

Question 6

What is Ionic vs Non-Ionic contrast

Answer 6

Ionic= when one substance is dissolved into another forming two charged particles (anion=neg, cation=positive)
- Have more effects.

Non Ionic= Do not dissolve into charged particles

Question 7

what is the osmolarity of contrast media, and what is it responsible for

Answer 7

measure of how many particles are dissolved in water

responsible for:
warm feeling
nausea, vomiting
renal damage
blood barrier damage

Question 8

what effects can osmolarity have to red blood cells

Answer 8

isotonic (CM=RBC)
- no effect

hypertonic (CM>RBC)
- rbc’s loose water, shrink

Hypotonic (CM

Question 9

what is the viscosity of CM

Answer 9

• Thickness due to resistance

hot temp=faster movement

Question 10

what are some reactions to CM

Answer 10

Mild
- warmth, vomit, nausea, cough

Moderate
- fascial edema, larnygeal edema, severe vomiting

Servere.
- hypotensive shock, cardiac arrest, convolsions.

• can occur 1hour- 1 week after

Question 11

high risk patients to CM reactions

Answer 11

• Old
• Asthma
• Previous reaction
• Known heart condition
• sickel cell
• anxious patients
• known renal damage.

Question 12

measures to ensure safe environment

Answer 12

• use non-ionic
• Calm environment
• pre med
• Keep pt monitored for 30 mins

Question 13

Why check blood creatine

Answer 13

amount of creatine in blood is indicator of how kidney function.
Normal creatine should be 0.6-1.2mg
(eGFR is better -) should be less then 45ml/min

Question 14

What is extravasation

Answer 14

when CM leaks out of BV

can cause compartment syndrome