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CT > Contrast Media > Flashcards

Contrast Media Flashcards

1
Q

What are the types of contrast media?

A

Positive and negative

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2
Q

What are types of positive contrast media (administration)?

A

Oral or IV

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3
Q

What are examples of positive contrast media?

A
  1. Iodine
  2. Barium
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4
Q

How do positive contrast media appear radiographically?

A

High density and white

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5
Q

What are types of negative contrast media (administration)?

A

CO2 or room air (rectal) or gas crystal

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6
Q

How does negative contrast media appear radiographically?

A

Low density and black

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7
Q

What is osmolality?

A

Number of particles in a solution per unit liquid

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8
Q

What is viscosity?

A

Thickness or friction of the fluid as it flows

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9
Q

What is iconicity?

A

Whether a solution contains molecules that form ions or not (aka ionic or non ionic)

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10
Q

What is clearance?

A

The body distributing and excreting the iodinated contrast through the kidneys

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11
Q

The body excretes contrast nearly exclusively by the kidneys via . . .

A

Glomerular filtration

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12
Q

What is the half life of contrast in a patient with normal renal function?

A

2 hours

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13
Q

What do LOCM and HOCM stand for?

A

LOCM = Low Osmolality Contrast Media
HOCM = High Osmolality Contrast Media

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14
Q

What type of IVs are used for venous access?

A

Indwelling catheter or CVC (if there is one)

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15
Q

What is the best vein to use for venous access?

A

Median cubital

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16
Q

What may need to be changed if a small vein is used to contrast?

A

Injection rate

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17
Q

What medical history may be gathered during pre injection interviews (aka contraindication)?

A
  1. Allergies
  2. Asthma
  3. Renal function
  4. Thyroid disease
  5. Pregnancy
  6. Diabetic (on metformin)
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18
Q

What lab work must be gathered and considered before contrast administration?

A

Creatinine and GFR

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19
Q

What basic information must be gathered during patient preparation(4)?

A
  1. Medical history
  2. Lab work
  3. Patient educating about exam and informed consent
  4. Documentation
20
Q

What type of contrast can cause adverse reactions?

A

Iodinated contrast

21
Q

What are the types of contrast adverse reactions(3)?

A
  1. Mild
  2. Moderate
  3. Severe
22
Q

What are symptoms of a mild adverse reaction?

A

Cough, itching, hives, eye swelling, nasal congestion

23
Q

What is the treatment for mild adverse reactions?

A

Over the counter antihistamines (ex: Benadryl)

24
Q

What is the role of the tech during mild adverse reactions?

A

Monitor the patient and tell radiologist

25
Q

What are symptoms of moderate adverse reactions?

A

Respiratory difficulty, pulse change, hyper or hypotension

26
Q

What is the treatment for moderate adverse reactions?

A

IV Benadryl

27
Q

What is the role of the tech for moderate adverse reactions?

A

Assess vitals, inform rad

*maintain IV access in case drug admin is required or out one back in!

28
Q

What are symptoms of a severe adverse reaction?

A

Substantial respiratory distress, unresponsive, convulsions, cardiac arrest

29
Q

What is the treatment of a severe adverse reaction?

A

CPR or oxygen or something

30
Q

What is the role of the tech in a severe adverse reaction?

A

Call a code blue and alert the rad, be an extra set of hands but get out of the way

31
Q

What do you do if a patient has had a previous contrast allergic reaction?

A
  1. Change the contrast agent (omnipaque or isovue)
  2. Premeditate the patient
32
Q

How do you pre medicate the patient before an exam with a contrast allergy?

A

13 hrs before appt: 50mg or prednisone

7 hrs before appt: 50mg or prednisone

1 hr before appt: 50mg of prednisone + 50mg diphenhydramine/20mg cetirizine

33
Q

What causes chemotoxic reactions?

A

Physicochemical properties of contrast media, dose, and speed of injection

34
Q

What might happen if metformin is taken during exam and kidney function changes?

A

May cause lactic acidosis

35
Q

What might happen if metformin is taken during exam and kidney function changes?

A

May cause lactic acidosis

36
Q

What is CIN?

A

Contrast Induced Nephropathy

Toxicity to kidneys due to acute increases in SeCr

37
Q

What is extravasation?

A

Leakage of blood or other fluid (i.e. contrast) into surrounding tissue causing inflammation

38
Q

Ways to avoid extravasation

A
  1. Indwelling catheter with flexible cannula (18 to 20 gauge)
  2. Monitor injection site
  3. Keep contrast media warm
  4. Use LOCM
39
Q

How do you treat extravasation?

A
  1. Stop injecting
  2. Notify rad
  3. Elevate + apply ice pack
40
Q

What are complications of extravasation?

A

Ulceration, necrosis, compartment syndrome

41
Q

What are the three phases of tissue enhancement?

A
  1. Bolus/arterial phase
  2. Non equilibrium phase
  3. Equilibrium phase
42
Q

Bolus phase

A

Starts: ~20 sec after injection

Contrast starts in peripheral vein, through mediastinum, to and out of the aorta (appear bright)

*cortex of kidney enhanced

43
Q

Nonequilibrium phase

A

Starts: ~60 to 80 sec after injection

Venous structures now appear opacified, liver parenchyma bright as well

Homogenous kidney enhancement (in tubules now)

44
Q

Equilibrium phase

A

Starts: 2 min after Bolus phase

Highlights organ parenchyma, not vascular structures enhanced

Kidneys no longer enhanced

45
Q

What factors affect enhancement quality?

A
  1. Patient weight
  2. Cardiac output
  3. Scan speed (delay increases = duration decreases)

CT (7 decks)

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