MRI MRI Contrast Agents

Question 1

What is the mechanism of action of gadolinium-based contrast agents (GBCAs) in MRI?

Accepted Answer

They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images

Answer

They directly emit radio waves that increase signal

Answer

They increase T2 relaxation time, increasing signal on T2-weighted images

Answer

They block radiofrequency pulses to create contrast

Question 2

Nephrogenic Systemic Fibrosis (NSF) is a serious complication associated with GBCA administration in patients with:

Accepted Answer

Severe renal impairment (GFR <30 mL/min/1.73m²)

Answer

Liver failure

Answer

Active infection

Answer

Allergy to iodine

Question 3

Which classification of GBCAs carries the LOWEST risk for NSF based on ACR guidance?

Accepted Answer

Group III (macrocyclic)

Answer

Group I (linear ionic)

Answer

Group II (linear non-ionic)

Answer

All GBCAs carry equal NSF risk

Question 4

The standard dose of a non-specific extracellular GBCA for most MRI examinations is:

Accepted Answer

0.1 mmol/kg

Answer

0.01 mmol/kg

Answer

0.05 mmol/kg

Answer

0.3 mmol/kg

Question 5

Which GBCA is approved by the FDA as a liver-specific agent taken up by hepatocytes?

Accepted Answer

Gadoxetate disodium (Eovist/Primovist)

Answer

Gadobutrol (Gadavist)

Answer

Gadopentetate dimeglumine (Magnevist)

Answer

Gadobenate dimeglumine (MultiHance)

Question 6

A patient reports a prior allergic-like reaction to a GBCA. Which of the following is the recommended premedication protocol?

Accepted Answer

Corticosteroid + antihistamine, with the first steroid dose 13 hours before injection

Answer

Antihistamine only, 1 hour before

Answer

Aspirin 24 hours before

Answer

No premedication is effective for GBCA reactions