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MRI Contrast Agents Flashcards

6 cards from real MRI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Iron oxide nanoparticles (e.g., USPIO) used as MRI contrast agents primarily shorten which relaxation time?

    Answer: T2 and T2* (susceptibility effect)

    Iron oxide particles create local magnetic field inhomogeneities that predominantly shorten T2 and T2*, causing signal loss (darkening) on T2-weighted and gradient echo images.

  2. A patient with a GFR of 45 mL/min/1.73m² requires a contrast-enhanced MRI. According to ACR guidelines, which GBCA group is preferred?

    Answer: Group III macrocyclic agents

    The ACR recommends macrocyclic GBCAs (Group III) for patients with reduced renal function (GFR 30–60) due to their superior thermodynamic and kinetic stability.

  3. The 'late gadolinium enhancement' (LGE) pattern of subendocardial distribution in cardiac MRI is most consistent with which diagnosis?

    Answer: Ischemic scar (prior myocardial infarction)

    Subendocardial LGE following a coronary territory distribution is the classic pattern of ischemic scar from prior myocardial infarction.

  4. What is the primary reason gadolinium-based contrast agents should not be used in patients undergoing hemodialysis without a specific clinical indication?

    Answer: Risk of NSF remains even after hemodialysis removes gadolinium

    While hemodialysis can remove most gadolinium, some residual free gadolinium remains after each session, and repeated exposure can still cause NSF in high-risk patients.

  5. In dynamic contrast-enhanced (DCE) MRI of the breast, which kinetic enhancement curve pattern is most concerning for malignancy?

    Answer: Washout (type III)

    A washout (type III) kinetic curve — rapid initial enhancement followed by signal decrease — is most suspicious for malignancy due to arteriovenous shunting in tumor neovasculature.

  6. Which of the following precautions is required before administering a GBCA to a breastfeeding mother, according to ACR recommendations?

    Answer: No precautions are required as only trace amounts enter breast milk

    The ACR states that GBCAs enter breast milk in very small amounts (<0.04%) and oral bioavailability is negligible; no interruption is required, though the mother may choose to withhold for 12–24 hours if concerned.