Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

THRALL - Thom > 6. Contrast media > Flashcards

6. Contrast media Flashcards

1
Q

What is the effective atomic number of soft tissue, Barium, Iodine and Gadolinium?

A

ST = 7

Ba = 56

I = 53

Gd = 64

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What advantages make barium a good GI contrast medium? what is one downside of pure barium?

A
  • Pros: Inert, not absorbed by GI, highly attenuating
  • Pure barium FLOCULATES - poor mucosal coverage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What complications / contraindications are associated with barium administration?

A
  • Leakage into abdomen / mediastinum-> Severe complication - forms fibinous adhesive peritonitis, with associated exudative process whitch results in hypovolameia and hypoalbuminaemia
  • Aspiration: Small volume likely Ok (used to do bronchography), but large volume can be fatal. May persist -> incorporation into macrophages, interstitium and regional nodes => TIME AND VOLUME DEPENDENT
  • Others: retention in colon (barolith), IV migration, allergic reactions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

If perforation likely, what agent should be used?

A
  • Non-ionic iodinated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Features of BIPs

A
  • 1.5 and 5mm sizes
  • CANNOT assess mucosa
  • Primarly used for : pyloric or intestinal obstruction. May be useful in partial, as smaller BIPS pass and larger BIPs cannot.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the effect of ionisation, osmolality and dimerisation on IODINATED contrast media

A
  • Ionisation -> greater osmolality as dissociate in solution
  • Osmolality -> effect on osmosis, resulting on more adverse reaction
  • Dimerisation -> adding additional iodine containing benzene rings into molecule = more iodine with less solute -> less osmolar. HOWEVER larger molecule, more viscous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Descrive contrast agent ratio

A

Contrast agent ratio = number of iodine atoms / number of particles in solution

=> DIMERS have 2 x ratio of non-ionic monomer, but more viscous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Iodinated contrast media adverse effects - OSMOLALITY ASSOCIATED

A

RBC dessication / small vessel obstrucion and hypoxia

Leukocyte dysfunction

Endothelial disturbance -> TE +- pulmonary oedema

Anticoagulant properties

Haemodynamic: vasodilation / osmotic hypervolaemia

Cardiac rhythm disturbances, HR and BP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What % of dogs and cats demonstrate >10% change in HR, RR or MAP following IV iodinated contrast admin?

A

Dogs :37.1%

Cats: 31%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What CATIONS are present in ionic contrast media

A

Either SODIUM or MEGLUMINE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What role does protein binding have on ionic contrast media? Give an example

A
  • Increased protein binding delays renal excretion and increased hepatic excretion

=> USE IN BILIARY CONTRAST e.g. meglumine iotroxate (Biloscopin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What specific effect can ionicity have on local tissues (besides increased osmolaltiy)?

A
  • Effects e.g. nerve condution, so no good for myelography
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Features of Ionic Monomers x 4. WHAT IS THE IP RATIO?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Features of Nonionic Monomers x 8. WHAT IS THE IP RATIO?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Features of Ionic Dimers x 1 WHAT IS THE IP RATIO

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Features of Non-ionic Dimers x 2. WHAT IS THE IP RATIO?

A
17
Q

Learn overall trends of iodinate contrast media table

A
18
Q

Learn contrast agent ratios for different groups of iodinated contrast

A
19
Q

Define and detail ACUTE / ANAPHYLACTOID contrast reactions

A
  • <1 hour after admin
  • Less severe: Vomiting, urticaria
  • More severe: Bronchospasm, layrngeal oedema, hypotensive shock, pulmonary oedema, respiratory or cardiac arrest

E.g. Horses with distal limb CT: 5% urticaria / oedema, 4% HR / BP changes

FATALITY ESTIMATED AT 1 in 80 PATIENTS!!!!!

20
Q

Define and detail LATE adverse contrast reactions

A

>1 hr - < 1 week

-> T cell mediated skin reactions.

21
Q

Define and detail Contrast Induced Nephropathy (CIN)

A
  • Definition: Increase in serum creat > 25% / >44micmol/L / 0.5mg/dl WITHIN 3 DAYS, where other causes ruled out
  • Rx features: persistent nephrogram 24-48hrs post
  • Risk factors: Renal impairment (particularly diabetic neprhopathy in people), dehydration, CHF, nephrotoxic drugs (NSAIDS, aminoglycosides), Metformin administration

=> increased creat seen within 1 week in 7.6% of dogs in one study

22
Q

Detail the effects of iodinated contrast on thyroid function

A
  • Iodine induced thyrotoxicosis - advised to not give to HyperT people. NOT REPORTED IN ANIMALS
  • Small amount of free iodine -> may interfere with uptake of radioactive iodine

=> Advise delay (circa 14 days) between contrast and RI

23
Q

What adverse effect is reported with negative contrast?

A
  • Air embolism
  • CO2 or NO2 (MORE SOLUBLE) preferred over room air
24
Q

What effect do paramagnetic contrast agents have on T1 and T2 relaxation times?

A
  • SHORTEN BOTH T1 AND T2

=> Increased T1 signal, decreased T2 signal

E.g. Gad, manganese

Gad (heavy metal) used as has most pronounced shortening effect on T1 relaxation times

25
Q

What toxic effects does Gad have? How is this avoided?

A
  • Hepatic necrosis! Highly toxic
  • Chelated to limit tox
26
Q

What are the two broad categories of Gad based agents?

A
  • Non-specific extracellular -> act like nonionic iodine and excreted by kidney
  • Hig relaxivity / Organ specific -> protein bound, excreted e.g. by hepatobiliary system
27
Q

What are linear Gad agents, and Features of linear Gad agents x 6

A
  • Linear vs cyclic refers to ligand bound to Gad. Linear less stable
28
Q

What are macrocyclic gad agents? Details of x 3

A

Macrocyclic -> surround gad ion, more stable than linear

29
Q

List adverse effects associated with Gad

A
  • Rarer than iodine
  • Acute: renal / CIN (uncommon), mild haemotdynamic, anaphlyaxis reported

=> Non renal effects less common because, despite potential high osmolality of some agents, LOWER DOSES of agent

30
Q

What is nephrogenic systemic fibrosis (NSF)?

A
  • Gad associated adverse effect in reduced renal function -> NOT DESCRIBED IN ANIMALS
  • Longer retention of gad in body -> more free gad -> Macrophages -> fibrotic changes => thickenign / hardening of skin, muscle weakness, bone pain, joint contractures, major involvement of lower extremitites
  • Occurs weeks to years after
  • ASSOCIATED WITH LESS STABLE LINEAR AGENTS -> tend to use cyclic agents now
31
Q

How is a bubble study performed?

A
  • Injection of agitated saline in venous catheter -> Visualised in R SIDE of heart
  • Will pass into pulmonary circulation, and not reach L side as break down (large bubbles cannot pass through capillary bed)
  • Should not arrive in L side unless R-> L shunt.
32
Q

Compare and contrast CEUS agents -> 0, 1st and 2nd gen

A
  • Agitated saline -> large air bubbles, cannot pass through pulmonary circulation (cardiac bubble studies)
  • 1st gen (e.g. Levovist) -> Smaller air bubbles, stabilised by surfactant. More stable, longer window. BUT still dissolution into blood so reduced SNR
  • 2nd gen (e.g. Sonovue) -> smaller iner gas bubbles, more stable, longer window, insoluble!
33
Q

What parameters affect microbubble behaviour? Which one is most important, and how do the bubble behave at different settings?

A
  • ACOUSTIC POWER, resonance frequency, depth, properties of agent
  • POWER MOST IMPORTANT

Mechanical index (MI) = summarises contribution of factors to power e.g. output, transmitted freq, attenuation with depth.

MI < 0.2 = bubbles oscillate in linear fasion, similar to surrounding tissue

MI 0.2-0.5 = non-linear oscillation, generate harmonics -> differentiate from tissue

MI >0.5 = expand and destroyed -> transient strong non linear echo

34
Q

List adverse reactions reported with CEUS

A
  • Very uncommon: nausea, headaches reported in people
  • In dogs: collapse, vomiting reported. 1 severe adverse reactiont to Opitson -> likley due to human albumin content

THRALL - Thom (40 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions