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Question 1MRI Physics and Instrumentation

Which component of an MRI system is primarily responsible for generating the main static magnetic field B0?

  1. The superconducting coil Correct answer.
  2. The radiofrequency body coil
  3. The shim coil assembly
  4. The gradient coil set

Explanation

The main static field B0 in modern clinical scanners is produced by a superconducting solenoid coil cooled by liquid helium. RF coils transmit and receive signal, gradients provide spatial encoding, and shim coils correct field inhomogeneity.

Question 2MRI Physics and Instrumentation

What is the approximate Larmor frequency of protons at 1.5 T?

  1. 42.6 MHz
  2. 128 MHz
  3. 21.3 MHz
  4. 63.9 MHz Correct answer.

Explanation

The Larmor frequency equals the gyromagnetic ratio (about 42.58 MHz/T for protons) multiplied by field strength. At 1.5 T this gives approximately 63.9 MHz, and the value scales linearly with B0.

Question 3MRI Physics and Instrumentation

During which MRI sequence segment is the radiofrequency receiver typically active to acquire the MR signal?

  1. During the RF excitation pulse
  2. During the readout gradient echo or spin echo Correct answer.
  3. During the slice-selection gradient ramp
  4. During the gradient spoiler phase

Explanation

Signal is sampled while the readout gradient is applied at the echo, when transverse coherence refocuses. Excitation, gradient ramps, and spoilers are preparation periods without signal acquisition.

Question 4MRI Physics and Instrumentation

What is the primary purpose of gradient coils in MRI?

  1. To amplify the received signal
  2. To provide spatial encoding of the MR signal Correct answer.
  3. To generate the static magnetic field
  4. To cool the superconducting magnet

Explanation

Gradient coils produce small, linear, time-varying field gradients along x, y, and z that encode spatial position through frequency and phase. They do not create the main field or amplify signal.

Question 5MRI Physics and Instrumentation

Which tissue property most directly determines the T1 relaxation time of a tissue?

  1. The strength of the readout gradient
  2. The local magnetic susceptibility
  3. The proton density of the tissue
  4. The rate of molecular tumbling and the efficiency of spin-lattice energy transfer Correct answer.

Explanation

T1 relaxation reflects recovery of longitudinal magnetization through energy exchange between spins and their molecular lattice. Molecular motion near the Larmor frequency makes this transfer efficient and shortens T1.

Question 6MRI Physics and Instrumentation

What does the term 'flip angle' describe in an MRI experiment?

  1. The angle of the receiver coil relative to B0
  2. The angle through which net magnetization is rotated by an RF pulse Correct answer.
  3. The phase difference between two gradient echoes
  4. The angle between the slice plane and the magnet bore axis

Explanation

A flip angle is the rotation of net magnetization away from the z-axis produced by an RF pulse, determined by pulse amplitude and duration. It governs how much longitudinal magnetization becomes transverse.

Question 7MRI Physics and Instrumentation

Which of the following best describes the function of a Faraday cage in an MRI suite?

  1. It shields the magnet from external acoustic noise
  2. It prevents external RF interference from entering the scan room Correct answer.
  3. It confines the static fringe field to the scan room
  4. It provides passive shimming of the main field

Explanation

The RF shield, or Faraday cage, blocks external electromagnetic signals from corrupting the very weak MR signal. It does not affect the static field or acoustic noise.

Question 8MRI Physics and Instrumentation

In a spin-echo sequence, what is the role of the 180-degree refocusing pulse?

  1. It saturates fat signal before acquisition
  2. It rephases static-field dephasing to form a spin echo Correct answer.
  3. It reverses the direction of the readout gradient
  4. It shortens the T1 of the tissue

Explanation

The 180-degree pulse flips the phase of precessing spins so that static dephasing accumulated from field inhomogeneity is reversed, producing a spin echo at TE. It does not alter intrinsic relaxation times.

Question 9MRI Physics and Instrumentation

A technologist increases the receiver bandwidth from 32 kHz to 64 kHz while keeping other parameters constant. What is the expected effect on the signal-to-noise ratio?

  1. SNR increases by a factor of about 1.4
  2. SNR remains unchanged
  3. SNR increases by a factor of two
  4. SNR decreases by a factor of about 1.4 Correct answer.

Explanation

Noise is proportional to the square root of the receiver bandwidth, so doubling bandwidth increases noise by about 1.41 while signal is unchanged, lowering SNR by that factor. Narrower bandwidths therefore improve SNR at the cost of chemical shift and longer readout.

Question 10MRI Physics and Instrumentation

Which parameter change will most directly reduce the specific absorption rate (SAR) of an RF pulse sequence?

  1. Increasing the repetition rate of RF pulses
  2. Decreasing the RF pulse duration for a fixed flip angle Correct answer.
  3. Increasing the flip angle
  4. Increasing the duty cycle of the RF amplifier

Explanation

SAR from RF deposition scales with the square of flip angle and inversely with pulse duration, so shortening the pulse for the same flip angle reduces energy deposition. Higher flip angles and more frequent pulses increase SAR.

Question 11MRI Physics and Instrumentation

Why does increasing the main field strength from 1.5 T to 3.0 T improve the intrinsic SNR of proton imaging?

  1. The receiver coil noise decreases to zero
  2. The equilibrium magnetization and induced signal scale approximately with B0 Correct answer.
  3. The proton density of tissue increases at higher field
  4. The relaxation times become longer for all tissues

Explanation

Equilibrium longitudinal magnetization is proportional to B0, so the available signal grows with field strength. This produces an approximately linear gain in intrinsic SNR, although T1 lengthening and other trade-offs accompany it.

Question 12MRI Physics and Instrumentation

A gradient echo sequence uses a short TE and a small flip angle to acquire a fast 3D volume. Which factor most limits the minimum achievable TR in this sequence?

  1. The number of phase-encoding steps
  2. The T1 of the tissue being imaged
  3. The receiver bandwidth setting
  4. The duration of the RF pulse and gradient switching time Correct answer.

Explanation

Gradient echo TR is bounded by hardware timing: RF pulse duration plus gradient ramp and settling times. Short TRs require fast gradients and short RF pulses, independent of tissue T1.

Question 13MRI Physics and Instrumentation

Which statement correctly describes the relationship between the slice thickness and the slice-selection gradient for a fixed RF bandwidth?

  1. Thicker slices require a shallower slice-select gradient Correct answer.
  2. Thicker slices require a steeper slice-select gradient
  3. Slice thickness is independent of the slice-select gradient
  4. Slice thickness depends only on the readout gradient

Explanation

Slice thickness equals RF bandwidth divided by the gyromagnetic ratio times the slice-select gradient amplitude. For a fixed bandwidth, a shallower gradient spans a wider frequency range and gives a thicker slice.

Question 14MRI Physics and Instrumentation

What is the main consequence of a poorly adjusted first-order shim on a spin-echo image?

  1. Increased geometric distortion from susceptibility
  2. Reduced RF penetration into the patient
  3. Shortened T2 relaxation of tissue
  4. Residual banding and signal loss from field inhomogeneity Correct answer.

Explanation

Imperfect shimming leaves field inhomogeneity that causes signal loss, banding, and fat-suppression failure. Spin echo refocuses static dephasing at the echo, so effects appear mainly as artifacts and imperfect suppression rather than gross distortion.

Question 15MRI Physics and Instrumentation

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

  1. The field of view
  2. Fine spatial detail and edges
  3. Image contrast and overall signal intensity Correct answer.
  4. The slice position

Explanation

Central k-space lines carry low-spatial-frequency information that governs contrast and bulk signal. Peripheral lines encode high-frequency detail such as edges and fine structure.

Question 16MRI Physics and Instrumentation

Which of the following is the most likely cause of a zipper artifact across an image?

  1. A gradient coil fault producing linear distortion
  2. Patient motion during the readout
  3. A miscalibrated transmit gain
  4. An external RF source leaking into the scan room Correct answer.

Explanation

Zipper artifacts arise from narrow-band external RF interference entering the scan room and being sampled by the receiver. They appear as lines at the frequency of the interfering signal.

Question 17MRI Physics and Instrumentation

Which sequence type is most sensitive to magnetic susceptibility differences between tissues?

  1. Inversion-recovery
  2. Fast spin-echo
  3. Gradient-echo Correct answer.
  4. Spin-echo

Explanation

Gradient echo lacks a 180-degree refocusing pulse, so static dephasing from susceptibility and field inhomogeneity is not corrected, making it sensitive to T2* effects. Spin-echo sequences refocus static dephasing.

Question 18MRI Physics and Instrumentation

What is the primary effect of increasing the number of signal averages (NEX) on image quality?

  1. Spatial resolution improves proportionally
  2. SNR improves by the square root of NEX Correct answer.
  3. SNR improves linearly with NEX
  4. Scan time decreases proportionally

Explanation

Averaging independent acquisitions reduces random noise by the square root of the number of averages while signal adds coherently. Scan time increases linearly with NEX.

Question 19MRI Physics and Instrumentation

Which hardware component converts the small MR signal from the receive coil into a digitized form for reconstruction?

  1. The spectrometer and analog-to-digital converter Correct answer.
  2. The gradient amplifier
  3. The helium compressor
  4. The transmit RF amplifier

Explanation

The receiver chain amplifies, demodulates, and digitizes the MR signal via analog-to-digital conversion in the spectrometer. Reconstruction then processes the digitized k-space data.

Question 20MRI Physics and Instrumentation

A protocol uses a 256 x 256 matrix with a 32 cm field of view. What is the approximate in-plane pixel size?

  1. 0.8 mm
  2. 1.25 mm Correct answer.
  3. 0.5 mm
  4. 2.5 mm

Explanation

Pixel size equals field of view divided by matrix size: 320 mm divided by 256 approximates 1.25 mm. This determines the in-plane spatial resolution.

Question 21MRI Physics and Instrumentation

Which factor most strongly determines the chemical shift artifact between fat and water at a given field strength?

  1. The flip angle of the excitation pulse
  2. The repetition time of the sequence
  3. The number of slices in the acquisition
  4. The receiver bandwidth and the readout gradient strength Correct answer.

Explanation

Chemical shift displacement in pixels equals the frequency difference divided by the bandwidth per pixel. Lower bandwidth or weaker readout gradients increase pixel shift, while higher bandwidth reduces it.

Question 22MRI Physics and Instrumentation

What is the purpose of a pre-emphasis or eddy-current compensation adjustment on a gradient system?

  1. To shorten the RF pulse duration
  2. To correct gradient waveform distortion caused by induced currents Correct answer.
  3. To increase the main magnetic field homogeneity
  4. To reduce acoustic noise from gradient switching

Explanation

Switching gradients induce eddy currents in conductive structures that distort the intended waveform. Pre-emphasis modifies the input waveform so the actual gradient matches the desired shape.

Question 23MRI Physics and Instrumentation

For a 3D spoiled gradient-echo sequence, which parameter combination best preserves T1 weighting while maintaining a short TR?

  1. A small flip angle with a short TE
  2. A large flip angle with a long TE
  3. A large flip angle with a short TR Correct answer.
  4. A small flip angle with a long TR

Explanation

In spoiled gradient echo, T1 weighting is maximized near the Ernst angle, which increases with shorter TR, so a relatively large flip angle with short TR gives strong T1 contrast efficiently. Long TRs reduce T1 weighting.

Question 24MRI Physics and Instrumentation

Why does parallel imaging with multiple receive coil elements allow reduced scan time?

  1. It uses spatial sensitivity information from coils to undersample k-space Correct answer.
  2. It eliminates the need for gradient encoding entirely
  3. It increases the RF duty cycle to speed relaxation
  4. It increases the main magnetic field strength during acquisition

Explanation

Parallel imaging exploits the differing spatial sensitivities of phased-array elements to reconstruct images from undersampled k-space, reducing phase-encoding steps. The acceleration is limited by coil geometry and SNR penalties.

Question 25MRI Physics and Instrumentation

A gradient echo EPI sequence at 3 T shows marked geometric distortion near air-tissue interfaces. Which acquisition change most directly reduces this distortion?

  1. Reducing the echo spacing and readout duration Correct answer.
  2. Increasing the echo train length
  3. Decreasing the receiver bandwidth
  4. Increasing the slice thickness

Explanation

EPI distortion arises from accumulated phase from field inhomogeneity during a long readout. Shortening echo spacing and total readout time reduces the phase error and thus the distortion.

Question 26MRI Physics and Instrumentation

Which property of the hydrogen nucleus makes it the primary signal source for clinical MRI?

  1. It has the highest gyromagnetic ratio of all stable nuclei.
  2. It is the only nucleus that does not precess in a magnetic field.
  3. It possesses a relatively large magnetic moment and is abundant in soft tissue. Correct answer.
  4. It is the only nucleus with zero spin.

Explanation

The proton has a large magnetic moment and is highly abundant in water and fat, giving strong signal. Nuclei with zero spin, such as carbon-12, do not give an MR signal. The proton's gyromagnetic ratio is high but not the highest of all nuclei.

Question 27MRI Physics and Instrumentation

Which statement correctly describes the Larmor equation for the precessional frequency of a proton?

  1. The frequency is independent of the magnetic field strength.
  2. The frequency is inversely proportional to the magnetic field strength.
  3. The frequency is proportional to the square of the magnetic field strength.
  4. The frequency is directly proportional to the magnetic field strength. Correct answer.

Explanation

The Larmor equation states that the precessional frequency equals the gyromagnetic ratio multiplied by the magnetic field strength. Thus frequency increases linearly with field strength. It is not squared, inverse, or independent of field strength.

Question 28MRI Physics and Instrumentation

What is the primary function of the radiofrequency (RF) body coil in a typical MRI scanner?

  1. To transmit RF excitation pulses and, in some systems, receive signal. Correct answer.
  2. To produce the spatial encoding gradients.
  3. To generate the main static magnetic field.
  4. To shim the magnetic field by generating direct currents.

Explanation

The body coil is typically a transmit/receive birdcage coil used to excite protons and can also receive signal, though dedicated surface coils are often used for reception. The main field is produced by superconducting magnets, gradients by gradient coils, and shimming by shim coils.

Question 29MRI Physics and Instrumentation

A spin-echo sequence uses a 90-degree excitation pulse followed by a 180-degree refocusing pulse. Which statement best describes the effect of the 180-degree pulse on transverse magnetization?

  1. It rotates the transverse magnetization by 180 degrees about the transmit coil axis, reversing its phase.
  2. It eliminates T2* dephasing by reversing the sign of the accumulated phase from static field inhomogeneities. Correct answer.
  3. It saturates the longitudinal magnetization to prevent T1 recovery.
  4. It returns longitudinal magnetization to the transverse plane.

Explanation

The 180-degree refocusing pulse flips the phase of the transverse magnetization so that static off-resonance dephasing is reversed, producing a spin echo at TE. It does not restore longitudinal magnetization to the transverse plane or saturate longitudinal magnetization.

Question 30MRI Physics and Instrumentation

In a gradient-echo sequence, which parameter change will most directly reduce the specific absorption rate (SAR) of the RF excitation?

  1. Increasing the number of slices.
  2. Decreasing the flip angle. Correct answer.
  3. Decreasing the repetition time (TR).
  4. Increasing the flip angle.

Explanation

SAR is proportional to the square of the flip angle for a given pulse duration, so reducing the flip angle lowers energy deposition. Increasing flip angle, decreasing TR, or increasing slices all tend to raise SAR. Therefore decreasing flip angle is the direct way to reduce SAR.

Question 31MRI Physics and Instrumentation

A 3.0 T MRI system is compared with a 1.5 T system. Assuming all other factors are equal, how does the intrinsic signal-to-noise ratio (SNR) of proton imaging typically change?

  1. It approximately quadruples.
  2. It decreases by half.
  3. It approximately doubles. Correct answer.
  4. It remains unchanged because SNR depends only on coil design.

Explanation

For proton imaging at higher field, the equilibrium magnetization and thus signal increase roughly linearly with field strength, while noise from the sample also changes; in practice SNR approximately doubles from 1.5 T to 3.0 T. It does not quadruple or remain unchanged.

Question 32MRI Physics and Instrumentation

Which of the following best describes the role of the gradient coils in MRI?

  1. They receive the MR signal and amplify it.
  2. They generate time-varying magnetic field gradients for spatial encoding and slice selection. Correct answer.
  3. They produce the static main magnetic field.
  4. They transmit RF pulses to excite protons.

Explanation

Gradient coils create linear variations in the magnetic field along x, y, and z axes, enabling slice selection, phase encoding, and frequency encoding. The main field is from the superconducting magnet, RF transmission from the body coil, and signal reception from receive coils.

Question 33MRI Physics and Instrumentation

A spin-echo image acquired at 1.5 T shows a bright rim at fat-water interfaces in the frequency-encode direction. Which acquisition change would most effectively reduce this chemical shift artifact?

  1. Increasing the receiver bandwidth. Correct answer.
  2. Decreasing the receiver bandwidth.
  3. Increasing the field of view.
  4. Increasing the echo time (TE).

Explanation

Chemical shift artifact is proportional to the frequency difference between fat and water divided by the receiver bandwidth per pixel. Increasing bandwidth reduces the pixel shift. Decreasing bandwidth or increasing TE would worsen or not reduce the artifact.

Question 34MRI Physics and Instrumentation

In a 2D Fourier transform image, what does the phase-encoding gradient primarily determine?

  1. The slice thickness.
  2. The frequency of the received signal.
  3. The location of the slice.
  4. The position of signal along the phase-encode direction in the image. Correct answer.

Explanation

The phase-encoding gradient introduces a phase shift that varies with position along one in-plane axis, which after Fourier transformation encodes spatial location in that direction. Slice thickness and position are determined by the slice-selection gradient and RF bandwidth, and frequency encoding determines position along the frequency direction.

Question 35MRI Physics and Instrumentation

Which of the following is the most likely cause of a zipper artifact across an MR image?

  1. Radiofrequency interference entering the scan room. Correct answer.
  2. A gradient coil fault causing nonlinearity.
  3. A poorly adjusted first-order shim.
  4. Patient motion during the scan.

Explanation

Zipper artifact appears as a line or band across the image and is typically caused by extraneous RF signals entering the shielded room, often from a door left open or a faulty penetration panel. Shim issues cause signal loss or distortion, gradient faults cause geometric distortion, and motion causes ghosting.

Question 36MRI Physics and Instrumentation

A technologist increases the number of signal averages (NEX) from 1 to 4. What is the expected effect on image quality?

  1. SNR increases by a factor of 16.
  2. SNR increases by a factor of 4.
  3. SNR remains unchanged.
  4. SNR increases by a factor of 2. Correct answer.

Explanation

Because noise is random, averaging multiple acquisitions increases SNR by the square root of the number of averages. Going from 1 to 4 averages increases SNR by the square root of 4, which is 2. The increase is not linear or quadratic.

Question 37MRI Safety and Patient Management

Which zone of the MRI facility is defined as the area where the magnetic field strength poses a risk to patients and personnel and is physically restricted?

  1. Zone II
  2. Zone IV Correct answer.
  3. Zone III
  4. Zone I

Explanation

The four-zone concept places the highest-risk, physically restricted region in Zone IV, where the field exceeds the level that could be dangerous to everyone present. Zone IV is where the scanner itself resides and access is fully controlled.

Question 38MRI Safety and Patient Management

A patient with a cardiac pacemaker that is labeled MR-conditional may be scanned only when:

  1. a surface coil is used instead of a body coil
  2. a radiologist signs a general consent form
  3. the patient's heart rate is below 60 beats per minute
  4. the field strength and conditions match the manufacturer's labeled conditions Correct answer.

Explanation

MR-conditional labeling means the device is safe only under the specific conditions the manufacturer specified, such as field strength, SAR limits, and coil type. Deviating from those conditions removes the assurance of safety.

Question 39MRI Safety and Patient Management

What is the primary purpose of the MR safety screening questionnaire completed before a patient enters the magnet room?

  1. To document the patient's insurance authorization
  2. To record the patient's prior radiation dose
  3. To identify implanted devices and ferromagnetic hazards Correct answer.
  4. To estimate the total scan time

Explanation

Screening aims to detect anything that could become a projectile or be affected by the magnetic field, including implants, foreign bodies, and loose metal. This protects the patient and staff before entering the controlled area.

Question 40MRI Safety and Patient Management

A ferromagnetic oxygen cylinder is accidentally brought into the scanner room. The most serious immediate hazard is:

  1. image signal-to-noise degradation
  2. a projectile effect with risk of injury Correct answer.
  3. quenching of the superconducting magnet
  4. radiofrequency skin burns

Explanation

Ferromagnetic objects experience strong attractive forces near the magnet and can be pulled at high speed toward the bore, causing serious injury or death. This projectile effect is the dominant immediate risk.

Question 41MRI Safety and Patient Management

Which statement best describes the acoustic noise hazard during MRI?

  1. Noise is produced only by the RF transmit coil
  2. Noise levels are always below occupational limits
  3. Noise arises from rapid gradient coil switching and requires hearing protection Correct answer.
  4. Noise is only a concern for pediatric patients

Explanation

Time-varying currents in the gradient coils create Lorentz forces that generate loud acoustic noise. Hearing protection is required for patients and anyone remaining in the scan room.

Question 42MRI Safety and Patient Management

During an MRI-guided procedure, a patient reports a warm, tingling sensation in an arm where an ECG lead cable rests against the skin. The first appropriate action is to:

  1. increase the SAR limit to complete the scan faster
  2. ignore it because warmth is expected
  3. switch off the patient monitoring entirely
  4. reposition the cable and check for conductive loops Correct answer.

Explanation

Tingling or warmth along a cable suggests RF-induced current and possible loop formation that can cause burns. Repositioning to eliminate loops and separate the cable from skin addresses the cause.

Question 43MRI Safety and Patient Management

A patient becomes anxious and claustrophobic just before entering the bore. Which management approach is most appropriate initially?

  1. Restrain the patient to prevent movement
  2. Offer reassurance, positioning aids, and a panic button Correct answer.
  3. Proceed rapidly without further communication
  4. Administer general anesthesia immediately

Explanation

Non-pharmacologic measures such as reassurance, prone or feet-first positioning, a mirror, and an audible panic device often allow completion of the scan. Anesthesia is reserved for cases where these measures fail and clinical need justifies it.

Question 44MRI Safety and Patient Management

Why must a patient's skin be kept dry and free of large conductive loops of cabling during scanning?

  1. To improve gradient linearity
  2. To reduce RF-induced currents that can cause burns Correct answer.
  3. To prevent the magnet from quenching
  4. To reduce acoustic noise

Explanation

Moist skin and closed loops of conductive material can concentrate RF currents, leading to localized heating and burns. Keeping skin dry and avoiding loops mitigates this risk.

Question 45MRI Safety and Patient Management

A patient with a metallic intraocular foreign body of unknown composition is referred for a brain MRI. The safest course of action is to:

  1. proceed because ocular metal is always non-ferromagnetic
  2. ask the patient to blink during the scan
  3. obtain documentation of the object's composition or perform appropriate imaging before scanning Correct answer.
  4. scan immediately with a reduced field of view

Explanation

An unknown metallic foreign body near the eye could be ferromagnetic and move under the field, risking vision loss. Confirming composition or using alternative imaging before entering the magnet is required.

Question 46MRI Safety and Patient Management

A patient with a known ferromagnetic cerebral aneurysm clip is scheduled for MRI. What is the correct determination?

  1. The scan is safe because the clip is small
  2. The scan is safe if a head coil is used
  3. The scan is contraindicated because of displacement risk Correct answer.
  4. The scan is safe if the patient is sedated

Explanation

Ferromagnetic aneurysm clips can be displaced or heated by the magnetic field, posing a risk of hemorrhage. Unless the clip is documented as MR-safe, scanning is contraindicated.

Question 47MRI Safety and Patient Management

During scanning, a patient with reduced sensation in the legs reports no discomfort but has a conductive loop of sheet under the leg. Why is this concerning even without symptoms?

  1. Loops increase acoustic noise
  2. Loops cause the magnet to quench
  3. Loops only affect image contrast
  4. Reduced sensation can mask RF heating, so burns may develop unnoticed Correct answer.

Explanation

Patients with impaired sensation may not perceive heating, so thermal injury can occur without warning. Preventing loops and monitoring the patient are essential.

Question 48MRI Safety and Patient Management

A patient is being scanned in a prone position, and a small ferromagnetic metallic fragment is suspected in the skin of the back. The technologist should:

  1. increase SAR to compensate for positioning
  2. evaluate the fragment's ferromagnetic potential and consult before scanning Correct answer.
  3. proceed because superficial fragments cannot move
  4. apply a warm compress to the area

Explanation

Even superficial ferromagnetic fragments can heat or move under the field and cause tissue injury. The fragment's nature must be assessed and the risk weighed before scanning.

Question 49MRI Safety and Patient Management

Which action best prevents a ferromagnetic projectile incident in the scanner room?

  1. Allowing staff to carry keys into the room
  2. Relying on signage alone to deter entry
  3. Keeping the door open during scans for ventilation
  4. Maintaining strict access control and a final ferromagnetic check at the door Correct answer.

Explanation

Projectile prevention depends on controlling access and performing a final check for ferromagnetic items immediately before entering the magnet room. Signage supports but does not replace active control.

Question 50MRI Safety and Patient Management

A patient with an MR-conditional infusion pump is scheduled. Which information is essential before scanning?

  1. The number of prior MRI examinations
  2. The labeled field strength, SAR limits, and permissible configuration Correct answer.
  3. The pump's battery age only
  4. The patient's preferred scanning position

Explanation

MR-conditional status is valid only when the planned scan matches the manufacturer's specified conditions, including field strength, SAR, and device configuration. Verifying these ensures safety.