Practice Test GeeksMRI - Magnetic Resonance Imaging Practice Test
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Physics 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 Physics flashcards as text

  1. In k-space, what does the center of k-space primarily determine?

    Answer: Image contrast

    The center of k-space contains low spatial frequencies that carry the bulk of image contrast and overall signal intensity.

  2. Which MRI sequence is most sensitive to hemorrhage detection because of its sensitivity to blood products?

    Answer: Gradient echo (GRE)

    Gradient echo sequences are sensitive to magnetic susceptibility differences caused by hemosiderin and deoxyhemoglobin, making them ideal for detecting hemorrhage.

  3. What is the effect of increasing the echo time (TE) on T2-weighted images?

    Answer: Increases T2 weighting by allowing more transverse relaxation

    A longer TE allows more time for T2 decay, so tissues with short T2 lose more signal, increasing contrast between tissues with different T2 values.

  4. During inversion recovery, the null point (TI) for fat suppression (STIR) is set to:

    Answer: TI = T1(fat) × ln(2)

    The null point occurs when the recovering longitudinal magnetization of fat passes through zero, which is at TI ≈ T1(fat) × ln(2) ≈ 0.693 × T1(fat).

  5. Which gradient is primarily responsible for frequency encoding in MRI?

    Answer: Readout gradient

    The readout (frequency-encoding) gradient is applied during signal acquisition, causing spins at different positions to precess at different frequencies.

  6. Gibbs ringing artifact is caused by:

    Answer: Truncation of k-space data at high spatial frequencies

    Gibbs ringing (truncation artifact) occurs when k-space is sampled with insufficient high-frequency data, causing oscillating bands near sharp tissue interfaces.

  7. What is the main advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

    Answer: Reduced acquisition time by undersampling k-space using multiple coil elements

    Parallel imaging uses the spatial sensitivity profiles of phased-array coils to reconstruct missing k-space lines, allowing faster acquisitions at the cost of some SNR.