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Free MRI practice questions.
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Try 15 questions on signal, image quality, and MR safety. Choose your answer, then use the explanation to check your reasoning.

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A quick note before you start

This set is for MRI students and technologists reviewing the basics. Some questions are straightforward; others ask you to keep track of the conditions. For the SNR questions, use the idealized model stated in the stem—not a promise of what every scanner will do.

If you are studying for the ARRT MRI registry, use this as a small review exercise alongside your course material. It does not cover the full exam blueprint or predict a passing score. These are independently written questions, not actual or recalled ARRT exam items. MRITechStudio is not affiliated with or endorsed by ARRT.

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Question 1 / 15 · SNR & artifactsYou increase the number of averages from 1 to 4. In an idealized acquisition with all other factors fixed, what happens to SNR and acquisition time?
Answer and explanation

Answer B: SNR doubles; acquisition time increases fourfold.

SNR follows the square root of the number of independent averages. Four averages give twice the modeled SNR and four times the acquisition time. Setup and other fixed overhead are outside this comparison.

How the choices compare

  • A. The SNR change is right, but four averages take four acquisition repetitions.
  • B. Both changes follow the fixed-parameter averaging model.
  • C. The SNR gain follows a square root, not a linear increase.
  • D. Independent averaging improves modeled SNR as well as increasing time.
Question 2 / 15 · SNR & artifactsReceiver bandwidth doubles while the acquired matrix, voxel dimensions, sequence timing and other signal factors stay fixed. What is the approximate SNR ratio relative to the original scan?
Answer and explanation

Answer D: 0.71×

In this limited model, SNR changes with the inverse square root of receiver bandwidth: 1/√2 is about 0.71. A real scanner may also change linked timing parameters, which this question holds fixed.

How the choices compare

  • A. Doubling receiver bandwidth does not double SNR.
  • B. This reverses the bandwidth relationship.
  • C. Bandwidth affects noise, even with the voxel dimensions fixed.
  • D. The fixed-parameter ratio is 1/√2.
Question 3 / 15 · SNR & artifactsYou halve the acquired slice thickness in a conventional 2D series. The in-plane voxel dimensions, number of averages, and other signal factors stay fixed. Which trade-off should you expect?
Answer and explanation

Answer A: Less through-plane partial-volume averaging, with lower modeled SNR.

Thinner acquired slices reduce through-plane mixing of tissues within a voxel. The smaller voxel also provides less signal: under these fixed conditions, halving thickness gives half the modeled SNR. The question asks about that trade-off before compensation.

How the choices compare

  • A. This pairs the finer through-plane sampling with the expected SNR cost.
  • B. The partial-volume change is right, but the smaller voxel lowers modeled SNR.
  • C. The SNR change is right, but thinner slices reduce through-plane partial-volume averaging.
  • D. Both changes are reversed for thinner acquired slices under these conditions.
Question 4 / 15 · Signal & spatial detailOn conventional T1- and T2-weighted spin-echo images, with no contrast agent or fluid suppression, how does stationary simple fluid usually appear?
Answer and explanation

Answer C: Dark on T1 and bright on T2.

Stationary simple fluid is usually dark on conventional T1-weighted images and bright on T2-weighted images. The wording matters: FLAIR deliberately suppresses fluid, and blood or protein-rich material may behave differently.

How the choices compare

  • A. This reverses the usual simple-fluid pattern.
  • B. Fluid suppression could darken fluid, but it is excluded here.
  • C. This is the usual pattern under the conditions in the question.
  • D. Simple fluid is not usually bright on conventional T1-weighted images.
Question 5 / 15 · Signal & spatial detailWhich combination generally favors T1 weighting in a conventional spin-echo acquisition? Treat “short” and “long” as relative to the tissues being imaged.
Answer and explanation

Answer B: Short TR and short TE.

A short TR preserves differences in T1 recovery; a short TE limits T2-related signal loss. This familiar pairing applies to conventional spin echo, not every sequence family.

How the choices compare

  • A. This generally favors proton-density weighting.
  • B. This is the conventional T1-weighted pairing.
  • C. This generally favors T2 weighting.
  • D. A long TE adds T2-related effects to a short-TR acquisition.
Question 6 / 15 · Signal & spatial detailA 240 mm field of view is sampled with 256 acquired pixels along one axis. Approximately how wide is an acquired pixel along that axis?
Answer and explanation

Answer B: 0.94 mm

Divide the field of view by the acquired matrix: 240 ÷ 256 = 0.9375 mm, or about 0.94 mm. Display interpolation does not change that acquired sampling interval.

How the choices compare

  • A. This would correspond to 512 samples across the same FOV.
  • B. This is 240 mm divided by 256.
  • C. This reverses FOV/matrix; 256 divided by 240 is not the pixel width in millimeters.
  • D. This would correspond to 128 samples across the same FOV.
Question 7 / 15 · SNR & artifactsAnatomy outside the selected field of view appears on the opposite side of a conventional Cartesian MR image. Which artifact best describes that pattern?
Answer and explanation

Answer D: Wraparound

Wraparound misplaces signal from anatomy outside the sampled field of view. The pattern is different from repeated motion ghosts, fat–water displacement or ringing near a sharp boundary.

How the choices compare

  • A. Motion ghosting produces replicas related to motion during acquisition.
  • B. Type 1 chemical shift displaces fat relative to water.
  • C. Gibbs ringing produces oscillating bands near a sharp signal boundary.
  • D. Outside-FOV anatomy appearing across the image is the defining clue.
Question 8 / 15 · SNR & artifactsIn a conventional Cartesian acquisition, periodic breathing produces repeated copies of abdominal anatomy along the phase-encoding direction. Which explanation best fits?
Answer and explanation

Answer C: Changing signal during phase encoding creates motion ghosts.

Periodic motion can create repeated ghosts along the phase-encoding direction. The stem describes changing anatomy over acquisition time, rather than a fat–water boundary or an undersized field of view.

How the choices compare

  • A. This describes type 1 chemical-shift misregistration.
  • B. This describes wraparound.
  • C. Periodic breathing and repeated phase-direction copies fit motion ghosting.
  • D. This describes Gibbs ringing.
Question 9 / 15 · SNR & artifactsWhat causes type 1 chemical-shift misregistration between fat and water in the frequency-encoding direction?
Answer and explanation

Answer A: Fat and water resonate at slightly different frequencies.

Fat and water resonate at slightly different frequencies. Frequency-based spatial encoding can therefore assign them different positions even at the same physical location. Type 1 misregistration is distinct from opposed-phase cancellation.

How the choices compare

  • A. The resonance-frequency difference is the mechanism being tested.
  • B. Different T1 recovery affects contrast, not this positional error.
  • C. Different T2 decay affects contrast, not this positional error.
  • D. Periodic movement can produce motion artifacts instead.
Question 10 / 15 · Signal & spatial detailWhich description correctly pairs the center and outer parts of Cartesian k-space?
Answer and explanation

Answer D: The center contains low spatial frequencies; the outer parts contain higher spatial frequencies.

K-space organizes spatial-frequency information. Its center contains low spatial frequencies, while the outer parts contain higher frequencies associated with finer changes in image structure. Each k-space sample contributes across the reconstructed image.

How the choices compare

  • A. This reverses the spatial-frequency arrangement.
  • B. K-space position is not a direct map of anatomical position.
  • C. Spatial frequency, rather than display brightness, distinguishes the regions.
  • D. This is the correct low-to-high spatial-frequency arrangement.
Question 11 / 15 · MR safetyAn implant is described as MR Conditional. What does that label mean?
Answer and explanation

Answer B: Its use in MRI depends on meeting the listed conditions.

MR Conditional applies only under the specified conditions for that device. The responsible MR team must verify the device and applicable conditions through the approved local workflow; the label alone is not clearance.

How the choices compare

  • A. This describes MR Safe, rather than MR Conditional.
  • B. The listed conditions define the limits of the MR Conditional designation.
  • C. This describes MR Unsafe, rather than MR Conditional.
  • D. An unverified safety status is not the meaning of MR Conditional.
Question 12 / 15 · MR safetyWhich part of the MR environment is primarily responsible for pulling a ferromagnetic object toward the scanner?
Answer and explanation

Answer C: The main static magnetic field and its spatial gradient.

The main static field, together with its spatial variation, can exert a strong translational force on ferromagnetic objects. Screening equipment for the MR environment helps prevent projectile events.

How the choices compare

  • A. RF energy is associated with heating hazards rather than this pulling force.
  • B. Gradient switching has other effects, including nerve stimulation and noise.
  • C. This is the field interaction behind projectile risk.
  • D. The received MR signal is not the source of the projectile force.
Question 13 / 15 · MR safetyThe system documentation describes its standard headphones as communication-only. For acoustic protection, which check matters most before scanning?
Answer and explanation

Answer D: That properly fitted hearing protection meets the system's sound-attenuation requirements.

Communication-only headphones do not establish adequate hearing protection. Check the system's specified attenuation requirements and the fit of the appropriate protection. Whether the patient can hear the intercom or tolerates the noise does not establish that attenuation.

How the choices compare

  • A. Intercom audibility checks communication, not the required noise attenuation.
  • B. A short sequence does not establish that the required acoustic protection is in place.
  • C. Subjective comfort is not a check of the specified attenuation.
  • D. This checks both the required acoustic protection and its proper fit.
Question 14 / 15 · MR safetyA patient is being positioned for MRI. Which preparation best addresses RF-related burn risk?
Answer and explanation

Answer A: Use the specified padding and cable arrangement in the manufacturer's instructions.

Use the specified insulating padding and follow the equipment's cable-routing instructions. Cable loops, skin-to-skin contact, and replacing the specified padding with ordinary bedding can introduce avoidable burn risks. Comfort checks complement these precautions; they do not replace them.

How the choices compare

  • A. This follows the specified precautions for contact points and cable routing.
  • B. Coiling cables can introduce conductive paths associated with heating risk.
  • C. Comfort alone does not remove the risk at skin-to-skin contact points.
  • D. Ordinary sheets are not a substitute for the specified insulating padding.
Question 15 / 15 · Signal & spatial detailAfter RF excitation, what directly produces the tissue signal detected by the MR receive coil?
Answer and explanation

Answer C: Precessing transverse magnetization in the excited tissue.

Precessing transverse magnetization produces a changing magnetic flux that induces the received signal. RF transmission excites the tissue; gradients encode position. Longitudinal recovery affects the signal available after later excitations but is not itself the detected RF signal.

How the choices compare

  • A. The excitation pulse prepares the tissue; it is not the received tissue signal.
  • B. Gradients encode spatial information but are not the source of the tissue RF signal.
  • C. Transverse precession induces the signal in the receive coil.
  • D. T1 recovery changes longitudinal magnetization rather than directly creating the received RF signal.
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Keep a useful next step

If a calculation tripped you up, try the SNR and scan-time learning lab. For pattern questions, revisit the MRI artifact guide. The T1 vs T2 guide helps with contrast basics.