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CAMRT MRI Exam study materials
CAMRT MRI Exam study resources

CAMRT MRI Exam practice questions

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Question 1Entry-to-Practice Competency Profile domains (not enumerated in source)

A technologist is preparing to image a patient with a ferromagnetic intraocular foreign body. Which safety concern is the primary reason MRI is generally contraindicated in this situation?

  1. The foreign body will cause the patient to experience claustrophobia during the scan
  2. The foreign body may be displaced or heated by the magnetic and radiofrequency fields, risking ocular injury Correct answer.
  3. The foreign body will trigger the scanner's emergency quench system automatically
  4. The foreign body will degrade the homogeneity of the static field and ruin image quality

Explanation

Ferromagnetic material in or near the eye can experience translational force from the static field and torque, and can heat from radiofrequency energy, potentially causing serious injury. For this reason a suspected metallic intraocular foreign body is a strong contraindication until its composition is established.

Question 2Entry-to-Practice Competency Profile domains (not enumerated in source)

Which tissue relaxation property primarily determines the contrast seen on a T1-weighted spin-echo image?

  1. Magnetic susceptibility
  2. Proton density
  3. T2 relaxation time
  4. T1 relaxation time Correct answer.

Explanation

A T1-weighted sequence uses a short repetition time and short echo time so that differences in T1 relaxation times between tissues dominate the signal. Tissues with short T1 recover longitudinal magnetization quickly and appear bright.

Question 3Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient with a cardiac pacemaker that is not MR-conditional is scheduled for an MRI. What is the most appropriate action for the technologist?

  1. Proceed but limit the scan to the head only
  2. Screen the patient and escalate to the radiologist, as the device is generally a contraindication Correct answer.
  3. Proceed with the scan if the patient signs a consent form
  4. Proceed using a lower static field strength to reduce risk

Explanation

Non-conditional pacemakers and leads can experience heating, induced currents, and unpredictable behavior in the MR environment, so they are generally contraindicated. The technologist must screen carefully and involve the supervising radiologist rather than deciding unilaterally.

Question 4Entry-to-Practice Competency Profile domains (not enumerated in source)

Which sequence is most susceptible to magnetic susceptibility artifact from a metallic orthopedic implant?

  1. Gradient-echo sequence Correct answer.
  2. Inversion-recovery sequence
  3. Fast spin-echo sequence
  4. Single-shot fast spin-echo sequence

Explanation

Gradient-echo sequences lack a refocusing 180-degree pulse, so they do not compensate for local field inhomogeneities caused by metal. This makes them markedly more susceptible to signal loss and geometric distortion than spin-echo techniques.

Question 5Entry-to-Practice Competency Profile domains (not enumerated in source)

What is the primary purpose of the radiofrequency shielding in an MRI scanner room?

  1. To keep the helium cryogen from escaping the magnet
  2. To reduce acoustic noise generated during scanning
  3. To prevent external RF signals from interfering with image acquisition Correct answer.
  4. To protect patients from the static magnetic field outside the room

Explanation

The RF shield, typically a copper-lined enclosure, keeps ambient radiofrequency signals from entering the scan room and contaminating the very weak MR signal. It also prevents the scanner's transmitted RF from escaping and interfering with other equipment.

Question 6Entry-to-Practice Competency Profile domains (not enumerated in source)

Which parameter change would most directly increase the spatial resolution of a spin-echo image?

  1. Increasing the slice thickness
  2. Reducing the number of signal averages
  3. Increasing the echo time
  4. Decreasing the field of view while keeping matrix constant Correct answer.

Explanation

Spatial resolution is set by the field of view divided by the matrix size. Reducing the field of view while holding the matrix constant decreases pixel size and improves spatial resolution, though at a cost of signal-to-noise ratio.

Question 7Entry-to-Practice Competency Profile domains (not enumerated in source)

Which agent is commonly used as an oral negative contrast agent to reduce signal from bowel in abdominal MRI?

  1. Barium sulfate suspension
  2. Iodinated contrast
  3. Gadolinium chelate
  4. Dilute ferumoxsil or a manganese-based preparation Correct answer.

Explanation

Negative oral agents such as ferumoxsil or manganese-based preparations shorten T2 and reduce bowel signal, helping distinguish bowel from adjacent pathology. Gadolinium is used intravenously for enhancement rather than as an oral negative agent.

Question 8Entry-to-Practice Competency Profile domains (not enumerated in source)

During an MR scan, a technologist notices the patient's skin is warm and the patient reports a tingling sensation near a monitoring lead. What is the most appropriate immediate response?

  1. Reduce the field of view and continue
  2. Stop the scan, remove the source of the induced current, and reassess the patient Correct answer.
  3. Continue scanning and document the event afterward
  4. Increase the repetition time to reduce heating

Explanation

Tingling near a lead suggests RF-induced current and potential heating at a contact point, which can cause burns. Scanning should be stopped, the offending lead or contact addressed, and the patient assessed before proceeding.

Question 9Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement best describes the difference between a gradient-echo and a spin-echo sequence in terms of the refocusing mechanism?

  1. Gradient-echo uses a 180-degree RF pulse to refocus spins; spin-echo uses gradients
  2. Both rely solely on a 180-degree RF pulse for refocusing
  3. Gradient-echo refocuses spins using magnetic field gradients; spin-echo uses a 180-degree RF pulse Correct answer.
  4. Both rely solely on gradients for refocusing

Explanation

Gradient-echo sequences reverse the read gradient to form an echo, refocusing dephasing caused by gradient application. Spin-echo sequences apply a 180-degree RF pulse that refocuses static field inhomogeneities as well, which is why they are more robust to susceptibility.

Question 10Entry-to-Practice Competency Profile domains (not enumerated in source)

A technologist wants to reduce motion artifact from respiration in a thoracic spine scan. Which approach is most appropriate?

  1. Increasing the bandwidth to reduce motion sensitivity
  2. Respiratory triggering or gating with the acquisition Correct answer.
  3. Increasing the flip angle
  4. Reducing the number of phase-encoding steps

Explanation

Respiratory gating or triggering synchronizes data acquisition to the patient's breathing cycle so that data are collected during a consistent phase of respiration. This reduces ghosting and blurring from diaphragmatic motion.

Question 11Entry-to-Practice Competency Profile domains (not enumerated in source)

In MR angiography, what is the main mechanism of blood vessel contrast in a time-of-flight sequence?

  1. Susceptibility differences between oxygenated and deoxygenated blood
  2. Contrast from gadolinium shortening of blood T1
  3. Inflow of fully magnetized spins into the imaging slice Correct answer.
  4. Differences in blood versus tissue proton density

Explanation

Time-of-flight angiography relies on flow-related enhancement: unsaturated spins flowing into the slice give high signal relative to saturated stationary tissue. It does not require contrast media.

Question 12Entry-to-Practice Competency Profile domains (not enumerated in source)

Which factor most strongly determines the signal-to-noise ratio of a spin-echo image?

  1. The number of phase-encoding steps only
  2. The patient's heart rate
  3. Voxel volume, number of averages, and receiver bandwidth Correct answer.
  4. The gradient slew rate

Explanation

Signal-to-noise ratio increases with larger voxel volume, more signal averages, and narrower receiver bandwidth, among other factors. These parameters trade off against resolution and scan time.

Question 13Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient has a tattoo on the arm that will be inside the bore during a shoulder scan. What is the appropriate technologist action?

  1. Ignore it since tattoos are never a concern
  2. Increase the field strength to shorten the scan
  3. Screen for the tattoo and apply a cold compress or pad, monitoring for heating Correct answer.
  4. Cancel all MRI for any patient with a tattoo

Explanation

Some tattoo inks contain metallic compounds that can heat or cause local artifact during scanning. The technologist should identify the tattoo, place a cool compress or padding, and monitor the patient during the scan.

Question 14Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement about the specific absorption rate is correct?

  1. SAR increases with higher RF power deposition and is regulated to limit tissue heating Correct answer.
  2. SAR is independent of patient weight and body composition
  3. SAR is a measure of the static magnetic field strength
  4. SAR applies only to gradient-echo sequences

Explanation

Specific absorption rate quantifies RF energy deposited per unit mass of tissue and is regulated to limit heating. It depends on factors such as flip angle, repetition time, body size, and coil type.

Question 15Entry-to-Practice Competency Profile domains (not enumerated in source)

Which artifact appears as a bright band or ghost shifted along the phase-encoding direction due to periodic motion?

  1. Zipper artifact
  2. Radiofrequency overflow artifact
  3. Ghosting artifact Correct answer.
  4. Chemical shift artifact

Explanation

Periodic motion such as respiration or cardiac pulsation produces ghost images replicated along the phase-encoding direction. This occurs because motion during encoding creates inconsistent phase information.

Question 16Entry-to-Practice Competency Profile domains (not enumerated in source)

Which parameter change would reduce chemical shift artifact at a fat-water interface?

  1. Increasing the echo time
  2. Decreasing the field of view
  3. Reducing the number of averages
  4. Increasing the receiver bandwidth Correct answer.

Explanation

Chemical shift artifact results from the small frequency difference between fat and water protons. Increasing receiver bandwidth reduces the frequency shift per pixel, thereby reducing the artifact.

Question 17Entry-to-Practice Competency Profile domains (not enumerated in source)

Which of the following is the most appropriate action for a technologist when a patient arrives with an unfamiliar implanted device and documentation is unavailable?

  1. Scan the patient because the device is likely safe
  2. Delay the scan and pursue device identification and radiologist review before proceeding Correct answer.
  3. Reduce the field strength to 0.2 T and proceed
  4. Refuse to scan and send the patient home without further consultation

Explanation

When implant status is unknown, the technologist should not proceed until the device is identified and its MR safety status is verified with the supervising radiologist. This follows the principle of not exposing a patient to unknown risk.

Question 18Entry-to-Practice Competency Profile domains (not enumerated in source)

What is the purpose of the prescan or auto-shim step in an MRI examination?

  1. To set the receiver bandwidth automatically
  2. To calibrate the patient's heart rate for gating
  3. To determine the patient's SAR limit
  4. To optimize the homogeneity of the local magnetic field over the imaging volume Correct answer.

Explanation

Auto-shimming adjusts the shim coils to improve magnetic field homogeneity across the imaging volume, which reduces artifacts and improves fat suppression. It is performed before acquisition to optimize signal.

Question 19Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient is claustrophobic and anxious before entering the scanner. Which strategy is most appropriate for the technologist?

  1. Increase the gradient noise to distract the patient
  2. Proceed rapidly without explanation to minimize time in the bore
  3. Explain the procedure, offer a mirror or prism, and consider sedation per protocol Correct answer.
  4. Discontinue MRI for all anxious patients

Explanation

Clear communication, positioning aids such as mirrors, and protocol-approved sedation or anxiolysis help anxious patients complete the examination safely. Hurrying or refusing care is not appropriate.

Question 20Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement best explains why a spin-echo sequence is less sensitive to static field inhomogeneity than a gradient-echo sequence?

  1. Spin-echo uses stronger gradients for refocusing
  2. Spin-echo uses a shorter echo time by definition
  3. Spin-echo uses a 180-degree refocusing pulse that reverses dephasing from field inhomogeneity Correct answer.
  4. Spin-echo does not use RF pulses

Explanation

The 180-degree refocusing pulse in spin-echo reverses the phase accumulated from static field inhomogeneities, so they refocus at the echo time. Gradient-echo lacks this mechanism, so susceptibility and field inhomogeneity cause greater signal loss.

Question 21Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient with a programmable ventriculoperitoneal shunt needs a brain MRI. What is the most appropriate approach to ensure safety?

  1. Scan without regard to the valve setting
  2. Verify the shunt's MR-conditional status and program the valve to the appropriate setting before and after scanning Correct answer.
  3. Remove the shunt before scanning
  4. Proceed at any field strength because shunts are always MR-safe

Explanation

Programmable shunt valves can be affected by magnetic fields, potentially altering the pressure setting. The technologist should confirm the device's MR-conditional status and arrange for the valve setting to be checked and reprogrammed as needed.

Question 22Entry-to-Practice Competency Profile domains (not enumerated in source)

Which combination of parameters would most reduce scan time while preserving T2 weighting in a fast spin-echo sequence?

  1. Increasing the number of averages and repetition time
  2. Increasing echo train length and using a long echo time Correct answer.
  3. Increasing the field of view and slice thickness
  4. Decreasing the echo train length and increasing the matrix

Explanation

A fast spin-echo sequence acquires multiple echoes per repetition time, so a longer echo train length reduces scan time. Keeping a long echo time maintains T2 contrast, though very long echo trains can blur images.

Question 23Entry-to-Practice Competency Profile domains (not enumerated in source)

What is the primary reason for using a phased-array coil in MRI?

  1. To reduce the static field strength
  2. To reduce acoustic noise
  3. To improve signal-to-noise ratio over a larger region by combining multiple coil elements Correct answer.
  4. To eliminate the need for shimming

Explanation

Phased-array coils combine signals from multiple small elements, providing high signal-to-noise ratio over an extended field of view compared with a single coil. This is why they are widely used for body and neuroimaging.

Question 24Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient's ECG tracing shows a repeating bright artifact on the images at a fixed interval. What is the most likely cause and the appropriate correction?

  1. Chemical shift; increase bandwidth
  2. Motion; increase averages
  3. RF interference; add a notch filter or reposition leads Correct answer.
  4. Susceptibility; use spin-echo

Explanation

Repeating bright bands or spots synchronized with the cardiac cycle usually indicate RF interference from monitoring equipment or leads. Adding a notch filter or repositioning and securing the leads reduces this artifact.

Question 25Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement correctly describes the relationship between repetition time and T1 contrast in a spin-echo sequence?

  1. A short repetition time eliminates T1 contrast
  2. Repetition time has no effect on T1 contrast
  3. A long repetition time increases T1 weighting by allowing full recovery
  4. A short repetition time increases T1 weighting by allowing incomplete recovery of longitudinal magnetization Correct answer.

Explanation

With a short repetition time, tissues with different T1 values recover longitudinal magnetization to different degrees, producing T1 contrast. A long repetition time allows full recovery and reduces T1 weighting.

Question 26Entry-to-Practice Competency Profile domains (not enumerated in source)

In MRI safety terminology, what does the term 'MR Safe' indicate about an implanted device or object?

  1. The object poses no known hazard in any MR environment Correct answer.
  2. The object may be used only with active monitoring of the patient
  3. The object is safe only outside the magnet room
  4. The object is safe only in a scanner with a field strength of 1.5 T or lower

Explanation

'MR Safe' is an item that poses no known hazard in any MR environment, based on non-clinical testing and labeling. It is distinct from 'MR Conditional', which specifies conditions such as field strength, spatial gradient, and SAR limits under which the item is safe.

Question 27Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement best describes the origin of the acoustic noise heard during an MRI scan?

  1. The radiofrequency transmit coil resonates mechanically at the Larmor frequency
  2. The cryogen boil-off produces a continuous hissing sound transmitted through the bore
  3. The static field causes the patient table to vibrate against its rails
  4. Rapid switching of the gradient coils within the main magnetic field produces mechanical vibration Correct answer.

Explanation

Acoustic noise arises mainly from Lorentz forces acting on the gradient coils as current is switched rapidly in the strong static field, causing them to vibrate. The vibration is transmitted through the air and structure, producing the characteristic knocking sound.

Question 28Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient scheduled for a brain MRI reports a history of working with metal grinding and has not had orbital radiographs. What is the most appropriate action before scanning?

  1. Ask the patient to remove eyeglasses and proceed immediately
  2. Proceed with the scan because a head coil will limit the field exposure
  3. Screen for metallic foreign bodies and arrange appropriate imaging or clearance before entering the magnet room Correct answer.
  4. Place a wet cloth over the eyes to reduce the risk of heating

Explanation

A history of metal exposure raises concern for an intraocular or other metallic foreign body, which could move or heat in the magnetic field. The patient should be screened further and, if indicated, cleared by radiography or another appropriate method before entering the magnet room.

Question 29Entry-to-Practice Competency Profile domains (not enumerated in source)

Which sequence type is most commonly used to produce images with strong T2 weighting while keeping scan time acceptable?

  1. Single-echo spin-echo with a short repetition time
  2. Gradient-echo with a short repetition time and small flip angle
  3. Fast spin-echo with a long echo train Correct answer.
  4. Echo-planar imaging with a long repetition time

Explanation

Fast (turbo) spin-echo uses a long echo train to acquire multiple phase-encoding lines per repetition time, allowing long effective echo times for T2 weighting without an excessively long scan. A conventional single-echo spin-echo with a long echo time is much slower.

Question 30Entry-to-Practice Competency Profile domains (not enumerated in source)

Which tissue has the longest T2 relaxation time at typical clinical field strengths?

  1. Cerebrospinal fluid Correct answer.
  2. Liver
  3. Cortical bone
  4. Skeletal muscle

Explanation

Cerebrospinal fluid is essentially free water and has a very long T2, which is why it appears bright on T2-weighted images. Solid tissues such as muscle, liver, and bone have much shorter T2 relaxation times.

Question 31Entry-to-Practice Competency Profile domains (not enumerated in source)

What is the primary purpose of the radiofrequency receive coil in an MRI system?

  1. To produce the spatial encoding gradients
  2. To detect the MR signal emitted by excited nuclei Correct answer.
  3. To shim the main magnetic field
  4. To generate the static magnetic field

Explanation

The receive coil detects the oscillating MR signal produced by excited nuclei as they relax. Transmit coils deliver RF energy, while the main magnet and gradient coils perform different functions.

Question 32Entry-to-Practice Competency Profile domains (not enumerated in source)

Which contrast agent property makes gadolinium-based agents visible on T1-weighted images?

  1. They emit their own radiofrequency signal
  2. They alter the main magnetic field strength permanently
  3. They lengthen T2 relaxation of nearby water protons
  4. They shorten T1 relaxation of nearby water protons Correct answer.

Explanation

Gadolinium chelates are paramagnetic and shorten the T1 relaxation time of nearby water protons, increasing signal on T1-weighted images. They do not emit their own signal and do not permanently change the field.

Question 33Entry-to-Practice Competency Profile domains (not enumerated in source)

Which parameter is most directly related to the spatial encoding of position along the phase-encoding direction?

  1. The duration of the radiofrequency pulse
  2. The amplitude of the slice-selection gradient
  3. The area of the phase-encoding gradient Correct answer.
  4. The bandwidth of the receive coil

Explanation

Phase encoding relies on the area of the phase-encoding gradient, which determines how much phase accrual varies with position along that axis. Each phase-encoding step applies a different gradient area to encode spatial location.

Question 34Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient is scheduled for an MRI of the lumbar spine and reports a metallic hip prosthesis. What is the most appropriate first step?

  1. Scan immediately using a fast sequence to minimize exposure
  2. Refuse the scan because any metallic implant is an absolute contraindication
  3. Remove the prosthesis before the scan
  4. Verify the implant's MR Conditional status and documented conditions before scanning Correct answer.

Explanation

Many orthopedic implants are MR Conditional, so the technologist should identify the device and confirm that the scanning conditions match its labeling. Scanning without this verification could expose the patient to an avoidable risk.

Question 35Entry-to-Practice Competency Profile domains (not enumerated in source)

Which factor most directly determines the chemical shift, in pixels, between fat and water in an image?

  1. The receive bandwidth per pixel in the frequency-encoding direction Correct answer.
  2. The repetition time of the sequence
  3. The echo train length of the sequence
  4. The flip angle of the excitation pulse

Explanation

Chemical shift in pixels equals the frequency difference between fat and water divided by the bandwidth per pixel in the frequency-encoding direction. Increasing the receive bandwidth reduces the shift in pixels.

Question 36Entry-to-Practice Competency Profile domains (not enumerated in source)

During a scan, the technologist notices that the patient's arms are touching the bore and the patient reports warmth at the contact points. What is the most appropriate immediate action?

  1. Increase the receiver bandwidth to reduce heating
  2. Stop the scan and reposition the patient to avoid skin-to-skin or skin-to-bore contact Correct answer.
  3. Reduce the repetition time to shorten the scan
  4. Continue the scan because mild warmth is expected and harmless

Explanation

Localized heating at contact points can indicate RF-induced burns from current loops formed by skin-to-skin or skin-to-bore contact. The scan should be stopped and the patient repositioned with insulation or spacing to break the loop.

Question 37Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement best describes the effect of increasing the field of view while keeping the matrix constant?

  1. Pixel size and spatial resolution both remain unchanged
  2. Pixel size decreases and spatial resolution increases
  3. Pixel size increases and spatial resolution decreases Correct answer.
  4. Pixel size increases and spatial resolution increases

Explanation

With a fixed matrix, a larger field of view distributes the same number of pixels over a larger distance, increasing pixel size. Larger pixels reduce spatial resolution.

Question 38Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient with a cardiac pacemaker is referred for a shoulder MRI. What is the most appropriate action?

  1. Proceed with a reduced field of view to limit exposure
  2. Proceed because the shoulder is far from the heart
  3. Determine the device's MR Conditional status and follow its labeled conditions or consult the device manufacturer Correct answer.
  4. Proceed using only gradient-echo sequences

Explanation

Pacemaker status must be established before scanning, because many devices are MR Conditional with specific requirements such as field strength, SAR limits, and monitoring. Scanning without this verification is unsafe.

Question 39Entry-to-Practice Competency Profile domains (not enumerated in source)

Which artifact is characterized by signal displacement in the frequency-encoding direction caused by motion during the acquisition?

  1. Chemical shift artifact
  2. Zipper artifact
  3. Susceptibility artifact
  4. Motion artifact in the frequency-encoding direction Correct answer.

Explanation

Motion during the frequency-encoding gradient causes inconsistent phase and produces ghosting or displacement along the frequency-encoding direction. Motion effects along the phase-encoding direction are more commonly seen as periodic ghosts, but frequency-encoding displacement also occurs with motion.

Question 40Entry-to-Practice Competency Profile domains (not enumerated in source)

Which change would most effectively reduce a wraparound artifact along the phase-encoding direction?

  1. Increase the receiver bandwidth
  2. Reduce the repetition time
  3. Increase the echo time
  4. Increase the phase-encoding field of view or apply phase oversampling Correct answer.

Explanation

Wraparound, or aliasing, occurs when anatomy outside the field of view is mapped into the opposite side of the image along the phase-encoding direction. Enlarging the phase-encoding field of view or using oversampling prevents this mapping.

Question 41Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement correctly describes the relationship between the number of signal averages and image quality?

  1. Increasing averages raises signal-to-noise ratio by the square root of the number of averages but lengthens scan time Correct answer.
  2. Increasing averages shortens scan time proportionally
  3. Increasing averages reduces signal-to-noise ratio because of additional noise accumulation
  4. Increasing averages raises signal-to-noise ratio linearly with no change in scan time

Explanation

Averaging repeated acquisitions increases signal-to-noise ratio by the square root of the number of averages, because signal adds coherently while noise adds randomly. Scan time increases in direct proportion to the number of averages.

Question 42Entry-to-Practice Competency Profile domains (not enumerated in source)

What is the primary effect of a 180-degree refocusing pulse in a spin-echo sequence?

  1. It reverses accumulated phase differences to form a spin echo Correct answer.
  2. It flips longitudinal magnetization into the transverse plane
  3. It spoils residual transverse magnetization before the next repetition
  4. It selects the slice thickness

Explanation

The 180-degree refocusing pulse reverses the phase accrued from field inhomogeneity and chemical shift, producing a spin echo at the echo time. This refocusing is why spin-echo sequences are relatively insensitive to static field inhomogeneity.

Question 43Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient is anxious and moves during a brain MRI, degrading the images. Which approach is most appropriate to reduce motion artifact?

  1. Increase the field of view to hide the artifact
  2. Increase the echo time to improve contrast
  3. Explain the procedure, improve comfort, and consider a faster sequence or motion-robust technique Correct answer.
  4. Reduce the receiver bandwidth

Explanation

Addressing patient anxiety and comfort reduces motion at its source, and faster or motion-robust sequences limit the impact of residual movement. Increasing echo time or field of view does not solve the underlying motion problem.

Question 44Entry-to-Practice Competency Profile domains (not enumerated in source)

Which of the following best describes the function of the gradient coils in an MRI system?

  1. They transmit radiofrequency energy to excite nuclei
  2. They detect the MR signal during readout
  3. They generate the uniform static field for polarization
  4. They produce spatially varying magnetic fields for slice selection and spatial encoding Correct answer.

Explanation

Gradient coils create linear magnetic field gradients that encode position by varying frequency and phase across the imaging volume. They also perform slice selection when applied during RF excitation.

Question 45Entry-to-Practice Competency Profile domains (not enumerated in source)

Which artifact appears as a bright line across the image caused by extraneous radiofrequency energy entering the scan room?

  1. Chemical shift artifact
  2. Ghosting artifact
  3. Zipper artifact Correct answer.
  4. Susceptibility artifact

Explanation

Zipper artifact results from stray RF entering the shielded room, often through an open door or faulty penetration panel, and appears as a bright line across the image. Proper room shielding and door closure prevent it.

Question 46Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient with a metallic cochlear implant is referred for a brain MRI. What is the most appropriate action?

  1. Proceed because the implant is outside the imaging field of view
  2. Confirm the implant's MR Conditional status and follow the labeled conditions or obtain manufacturer guidance Correct answer.
  3. Proceed using a low flip angle to reduce heating
  4. Proceed with a shorter repetition time to limit exposure

Explanation

Cochlear implants vary in MR status, and many are MR Conditional with requirements such as field strength limits and magnet displacement precautions. Verification and adherence to labeling or manufacturer guidance are required before scanning.

Question 47Entry-to-Practice Competency Profile domains (not enumerated in source)

Which parameter change would most reduce the scan time of a two-dimensional spin-echo acquisition while keeping the field of view and matrix constant?

  1. Increasing the echo time
  2. Increasing the number of signal averages
  3. Increasing the repetition time
  4. Increasing the number of echoes acquired per repetition time Correct answer.

Explanation

Acquiring multiple echoes per repetition time reduces the number of repetitions needed to fill k-space, shortening scan time. Increasing averages, repetition time, or echo time would lengthen the scan.

Question 48Entry-to-Practice Competency Profile domains (not enumerated in source)

A patient has a ferromagnetic aneurysm clip of unknown type. What is the most appropriate action?

  1. Do not scan until the clip is identified as MR Conditional or MR Safe Correct answer.
  2. Proceed because the clip is small
  3. Scan with a reduced field of view to limit exposure
  4. Scan using only gradient-echo sequences

Explanation

Ferromagnetic aneurysm clips can move or heat in the magnetic field, posing a serious risk. Scanning should not proceed until the clip is identified as MR Safe or MR Conditional for the proposed conditions.

Question 49Entry-to-Practice Competency Profile domains (not enumerated in source)

Which statement best explains why the phase-encoding direction is usually chosen to be the shorter anatomic dimension?

  1. It reduces the echo time and improves signal-to-noise ratio
  2. It increases the receiver bandwidth automatically
  3. Fewer phase-encoding steps are needed, reducing scan time and wraparound Correct answer.
  4. It eliminates chemical shift artifact

Explanation

The number of phase-encoding steps is determined by the matrix along that axis, so using the shorter dimension reduces the number of steps and scan time. It also reduces wraparound by limiting the extent of tissue outside the field of view along that direction.

Question 50Entry-to-Practice Competency Profile domains (not enumerated in source)

A technologist observes a bright band at the fat-water interface in a gradient-echo image acquired with a low receiver bandwidth. Which change would most reduce this artifact?

  1. Decrease the field of view
  2. Increase the receiver bandwidth Correct answer.
  3. Increase the number of averages
  4. Increase the echo time

Explanation

Chemical shift artifact in pixels is the frequency difference between fat and water divided by the bandwidth per pixel, so increasing receiver bandwidth reduces the pixel shift. Echo time, field of view, and averaging do not change the frequency separation.