Practice Test GeeksMRI - Magnetic Resonance Imaging Practice Test
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Knowledge Flashcards

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

Read the first 7 Knowledge flashcards as text

  1. What is the Larmor frequency in MRI?

    Answer: The resonant frequency at which protons precess in a given magnetic field

    The Larmor frequency (ω₀ = γB₀) is the precise resonant frequency at which protons absorb and emit RF energy in the applied field.

  2. Which MRI sequence is most sensitive for detecting acute subarachnoid hemorrhage?

    Answer: FLAIR (Fluid Attenuated Inversion Recovery)

    FLAIR suppresses CSF signal, making subarachnoid blood appear hyperintense against a dark CSF background.

  3. What is the effect of increasing the number of signal averages (NSA/NEX) on MRI image quality?

    Answer: SNR improves proportionally to the square root of NSA

    Averaging multiple acquisitions improves SNR by a factor of √NSA, though it linearly increases scan time.

  4. Which MRI technique is used to assess brain perfusion by tracking the first pass of a gadolinium bolus?

    Answer: Dynamic Susceptibility Contrast (DSC) perfusion

    DSC perfusion MRI uses rapid T2*-weighted sequences to measure signal drop as gadolinium transits through the brain capillaries.

  5. A patient with a cochlear implant is scheduled for MRI. What is the primary concern?

    Answer: Device displacement or demagnetization by the static field and RF heating

    Cochlear implants contain magnets that can torque, displace, or demagnetize in the MRI field, posing significant safety risks.

  6. What does 'isotropic voxel' mean in MRI acquisition?

    Answer: Voxel with equal dimensions in all three spatial directions

    An isotropic voxel has identical length, width, and height, allowing high-quality multiplanar reformats without resolution loss.

  7. Which MRI contrast agent class is associated with the highest risk of nephrogenic systemic fibrosis (NSF)?

    Answer: Linear non-ionic agents

    Linear non-ionic (and some linear ionic) gadolinium agents release free Gd³⁺ more readily and carry the highest NSF risk in patients with severe renal impairment.