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

Gadolinium shortens the T1 relaxation time of surrounding water protons through dipole-dipole interactions, causing increased signal intensity on T1-weighted sequences.

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

NSF occurs almost exclusively in patients with severe kidney disease (GFR <30) because impaired renal clearance prolongs gadolinium exposure, allowing transmetallation and tissue deposition.

Question 3

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

Accepted Answer

Group III (macrocyclic)

Answer

Macrocyclic GBCAs (Group III) have a more stable cage-like structure that resists transmetallation and are associated with the lowest 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

The standard dose for most extracellular GBCAs is 0.1 mmol/kg body weight, which provides adequate contrast enhancement for most clinical applications.

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

Gadoxetate disodium (Eovist in the US, Primovist in Europe) is taken up by functioning hepatocytes via OATP transporters, providing hepatobiliary phase imaging for liver lesion characterization.

MRI - Magnetic Resonance Imaging Practice Test

MRI - Magnetic Resonance Imaging Practice Test

MRI MRI Contrast Agents