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MRI Artifacts 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.

Read the first 6 MRI Artifacts flashcards as text

  1. Which MRI artifact appears as a ghosting or smearing of bright structures in the phase-encoding direction?

    Answer: Motion (ghosting) artifact

    Motion artifact manifests as ghost images displaced in the phase-encoding direction because phase-encoding samples data over many TR intervals while frequency encoding is instantaneous.

  2. Chemical shift artifact of the first kind occurs at interfaces between fat and water and manifests as:

    Answer: A bright band and a dark band at the fat-water interface in the frequency-encoding direction

    First-kind chemical shift artifact creates a bright rim on one side and a dark void on the other side at fat-water interfaces in the frequency-encoding direction due to the 3.5 ppm resonance frequency difference.

  3. Gibbs (truncation) artifact is caused by:

    Answer: Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces

    Gibbs artifact arises from the Fourier series representation of sharp edges when high spatial-frequency k-space data is truncated, producing ringing lines parallel to the interface.

  4. Wraparound (aliasing) artifact in MRI is caused by:

    Answer: Structures outside the FOV contributing signal that is folded back into the image

    When anatomy extends beyond the selected FOV in the phase-encode direction, it is aliased and appears superimposed on the opposite side of the image.

  5. Which technique is most effective for reducing susceptibility artifact from a metallic implant in MRI?

    Answer: Use a spin-echo or fast spin-echo (FSE) sequence with narrow bandwidth

    Spin-echo and FSE sequences use 180° refocusing pulses that compensate for susceptibility-induced dephasing, and a narrow bandwidth reduces chemical shift but a wide bandwidth reduces susceptibility — MARS protocols use high bandwidth FSE.

  6. Zipper artifact on an MRI image appears as a line of alternating bright and dark pixels across the image, most often caused by:

    Answer: External RF interference from inadequate shielding or open RF cage door

    Zipper artifact is caused by external radiofrequency interference entering the scan room, typically due to an open waveguide, broken shielding, or improperly closed scanner room door.