MRSO EXAM 4 NEWEST 2026 ACTUAL EXAM COMPLETE 300 QUESTIONS AND CORRECT
DETAILED ANSWERS/NEWEST UPDATE
Question 1
The induction of electrical current in the presence of a changing magnetic field, which is the
primary mechanism behind peripheral nerve stimulation (PNS), is described by:
A) Ohm’s Law
B) Lenz’s Law
C) Faraday’s Law of Induction
D) Planck’s Law
E) Newton’s Second Law
Correct Answer: C) Faraday’s Law of Induction
Rationale: Faraday’s Law states that a time-varying magnetic field (dB/dt) will induce an
electromotive force (EMF), which can result in electrical currents within conductive tissues. In
MRI, the rapidly switching gradients induce these currents in the patient's body, potentially
stimulating nerves.
Question 2
Gadolinium-based contrast agents (GBCAs) have been found to be retained in the human body in
which of the following forms?
A) Only water-soluble forms
B) Only non-water-soluble forms
C) Both water-soluble and non-water-soluble forms
D) Only in gaseous forms within the lungs
E) Only as a stable chelate that is always excreted within 2 hours
Correct Answer: C) Both water-soluble and non-water-soluble forms
Rationale: Research has demonstrated that gadolinium can be retained in tissues (such as the
brain, bone, and skin) in both soluble and insoluble forms. This retention is a primary area of
study regarding long-term GBCA safety, particularly with linear agents.
Question 3
Which of the following pulse sequences would typically be the loudest during acquisition due to
rapid gradient switching?
A) Fast Spin Echo (FSE)
B) FLAIR
C) Conventional Gradient Echo
D) GRASS (Gradient Recalled Acquisition in the Steady State)
E) T1-Weighted Spin Echo
Correct Answer: D) GRASS
Rationale: GRASS and other steady-state gradient sequences require extremely fast and frequent
gradient switching. This mechanical vibration of the gradient coils against their mountings
creates higher acoustic noise levels compared to standard Spin Echo or FLAIR sequences.
, 2
Question 4
In terms of safety and the "missile effect," which type of magnetic field configuration typically
exhibits a steeper spatial magnetic gradient?
A) Horizontal B0 magnets
B) Vertical B0 magnets
C) They are always identical
D) Only 3.0T magnets
E) Permanent magnets only
Correct Answer: A) Vertical B0 magnets
Rationale: Vertical field magnets (often used in open MRI systems) generally have a steeper
spatial gradient (dB/dx) outside the bore than horizontal field magnets. This means the magnetic
pull on a ferromagnetic object can increase more rapidly over a shorter distance.
Question 5
The spatial magnetic gradient (dB/dx) typically reaches its maximum strength at what distance
from the isocenter of the magnet?
A) 0-5 cm
B) 5-20 cm
C) 30-60 cm
D) 100-150 cm
E) At the 5 Gauss line
Correct Answer: C) 30-60 cm
Rationale: While the static field (B0) is strongest at the isocenter, the spatial gradient (the change
in field strength over distance) is usually at its peak near the portal or just inside the bore,
typically in the 30-60 cm range. This is where the translational "pull" is most dangerous.
Question 6
What is the current ACR/radiology consensus regarding gadolinium administration and
breastfeeding mothers?
A) Mothers must stop breastfeeding for 48 hours.
B) Breastmilk should be pumped and discarded for 24 hours.
C) Gadolinium is found in breast milk in a stable, chelated form, and breastfeeding can typically
continue without interruption.
D) Gadolinium makes the milk toxic to the infant’s kidneys.
E) 50% of the maternal dose is excreted into the milk.
Correct Answer: C) Gadolinium is found in breast milk in a stable, chelated form, and
breastfeeding can typically continue without interruption.
Rationale: While it was previously suggested to "pump and dump," the current ACR manual
states that less than 0.04% of the maternal dose is excreted into breast milk and less than 1% of
, 3
that is absorbed by the infant's GI tract. Therefore, stopping breastfeeding is not considered
necessary.
Question 7
Which hardware parameter directly influences the potential for peripheral nerve stimulation
(PNS)?
A) The static magnetic field strength (Bo)
B) The Slew Rate
C) The helium pressure
D) The flip angle
E) The SAR limit
Correct Answer: B) The Slew Rate
Rationale: Slew rate is the speed at which a gradient can reach its maximum amplitude (mT/m/s).
A higher slew rate means a more rapid change in the magnetic field over time (dB/dt), which
increases the likelihood of inducing currents strong enough to stimulate nerves.
Question 8
Which of the following pulse sequences is associated with the least amount of patient heating
(RF deposition)?
A) Fast Spin Echo (FSE)
B) STIR (Short Tau Inversion Recovery)
C) Incoherent Gradient Echo
D) EPI (Echo Planar Imaging)
E) 3D TOF MRA
Correct Answer: D) EPI
Rationale: EPI is an extremely fast sequence that uses a single RF excitation pulse to acquire
multiple lines of K-space. Compared to FSE or STIR, which use multiple 180-degree refocusing
pulses (high RF energy), EPI generally has lower RF deposition and SAR.
Question 9
A patient requires a brain MRI but has an aneurysm clip. Which of the following metals, if used
in the clip’s construction, would make the scan "MR Unsafe"?
A) Titanium
B) Elgiloy
C) Phynox
D) 405 Stainless Steel
E) 316 Stainless Steel
Correct Answer: D) 405 Stainless Steel
Rationale: Titanium, Phynox, Elgiloy, and 316 Stainless Steel are generally considered non-
ferromagnetic (non-ferrous). However, 405 Stainless Steel and 17-7PH Stainless Steel are
ferromagnetic and would pose a significant risk of torque and displacement.
, 4
Question 10
Which of the following statements regarding Lenz’s Force is correct?
A) It only affects ferromagnetic objects like iron.
B) It occurs when an electrically conductive (but non-ferrous) object moves through a strong
magnetic field.
C) It is independent of the field strength.
D) It decreases as the speed of motion increases.
E) It attracts objects toward the isocenter.
Correct Answer: B) It occurs when an electrically conductive (but non-ferrous) object moves
through a strong magnetic field.
Rationale: Lenz's Law describes eddy currents induced in conductive materials (like aluminum
or copper) as they move through the Bo field. These currents create a magnetic field that opposes
the motion, resulting in a "drag" or "repulsive" force.
Question 11
If an MRI scanner is operating in "Normal Operating Mode," the Whole-Body Specific
Absorption Rate (SAR) must not exceed:
A) 1 W/kg
B) 2 W/kg
C) 4 W/kg
D) 8 W/kg
E) 10 W/kg
Correct Answer: B) 2 W/kg
Rationale: Normal Operating Mode is the mode in which none of the outputs have a value that
would cause physiological stress to patients. The limit is 2 W/kg. First-Level Controlled Mode
allows up to 4 W/kg.
Question 12
An "MR Conditional" labeling for an implant must specify parameters for which of the
following?
A) Static magnetic field (Bo) only
B) RF fields (B1) only
C) Switched gradient fields (dB/dt) only
D) Static field, RF fields, and Spatial Gradient fields
E) Only the weight of the patient
Correct Answer: D) Static field, RF fields, and Spatial Gradient fields
Rationale: MR Conditional means an item has been demonstrated to pose no known hazards in a
specified MR environment under specific conditions, which must include the field strength, the
maximum spatial gradient, and the SAR limits.
DETAILED ANSWERS/NEWEST UPDATE
Question 1
The induction of electrical current in the presence of a changing magnetic field, which is the
primary mechanism behind peripheral nerve stimulation (PNS), is described by:
A) Ohm’s Law
B) Lenz’s Law
C) Faraday’s Law of Induction
D) Planck’s Law
E) Newton’s Second Law
Correct Answer: C) Faraday’s Law of Induction
Rationale: Faraday’s Law states that a time-varying magnetic field (dB/dt) will induce an
electromotive force (EMF), which can result in electrical currents within conductive tissues. In
MRI, the rapidly switching gradients induce these currents in the patient's body, potentially
stimulating nerves.
Question 2
Gadolinium-based contrast agents (GBCAs) have been found to be retained in the human body in
which of the following forms?
A) Only water-soluble forms
B) Only non-water-soluble forms
C) Both water-soluble and non-water-soluble forms
D) Only in gaseous forms within the lungs
E) Only as a stable chelate that is always excreted within 2 hours
Correct Answer: C) Both water-soluble and non-water-soluble forms
Rationale: Research has demonstrated that gadolinium can be retained in tissues (such as the
brain, bone, and skin) in both soluble and insoluble forms. This retention is a primary area of
study regarding long-term GBCA safety, particularly with linear agents.
Question 3
Which of the following pulse sequences would typically be the loudest during acquisition due to
rapid gradient switching?
A) Fast Spin Echo (FSE)
B) FLAIR
C) Conventional Gradient Echo
D) GRASS (Gradient Recalled Acquisition in the Steady State)
E) T1-Weighted Spin Echo
Correct Answer: D) GRASS
Rationale: GRASS and other steady-state gradient sequences require extremely fast and frequent
gradient switching. This mechanical vibration of the gradient coils against their mountings
creates higher acoustic noise levels compared to standard Spin Echo or FLAIR sequences.
, 2
Question 4
In terms of safety and the "missile effect," which type of magnetic field configuration typically
exhibits a steeper spatial magnetic gradient?
A) Horizontal B0 magnets
B) Vertical B0 magnets
C) They are always identical
D) Only 3.0T magnets
E) Permanent magnets only
Correct Answer: A) Vertical B0 magnets
Rationale: Vertical field magnets (often used in open MRI systems) generally have a steeper
spatial gradient (dB/dx) outside the bore than horizontal field magnets. This means the magnetic
pull on a ferromagnetic object can increase more rapidly over a shorter distance.
Question 5
The spatial magnetic gradient (dB/dx) typically reaches its maximum strength at what distance
from the isocenter of the magnet?
A) 0-5 cm
B) 5-20 cm
C) 30-60 cm
D) 100-150 cm
E) At the 5 Gauss line
Correct Answer: C) 30-60 cm
Rationale: While the static field (B0) is strongest at the isocenter, the spatial gradient (the change
in field strength over distance) is usually at its peak near the portal or just inside the bore,
typically in the 30-60 cm range. This is where the translational "pull" is most dangerous.
Question 6
What is the current ACR/radiology consensus regarding gadolinium administration and
breastfeeding mothers?
A) Mothers must stop breastfeeding for 48 hours.
B) Breastmilk should be pumped and discarded for 24 hours.
C) Gadolinium is found in breast milk in a stable, chelated form, and breastfeeding can typically
continue without interruption.
D) Gadolinium makes the milk toxic to the infant’s kidneys.
E) 50% of the maternal dose is excreted into the milk.
Correct Answer: C) Gadolinium is found in breast milk in a stable, chelated form, and
breastfeeding can typically continue without interruption.
Rationale: While it was previously suggested to "pump and dump," the current ACR manual
states that less than 0.04% of the maternal dose is excreted into breast milk and less than 1% of
, 3
that is absorbed by the infant's GI tract. Therefore, stopping breastfeeding is not considered
necessary.
Question 7
Which hardware parameter directly influences the potential for peripheral nerve stimulation
(PNS)?
A) The static magnetic field strength (Bo)
B) The Slew Rate
C) The helium pressure
D) The flip angle
E) The SAR limit
Correct Answer: B) The Slew Rate
Rationale: Slew rate is the speed at which a gradient can reach its maximum amplitude (mT/m/s).
A higher slew rate means a more rapid change in the magnetic field over time (dB/dt), which
increases the likelihood of inducing currents strong enough to stimulate nerves.
Question 8
Which of the following pulse sequences is associated with the least amount of patient heating
(RF deposition)?
A) Fast Spin Echo (FSE)
B) STIR (Short Tau Inversion Recovery)
C) Incoherent Gradient Echo
D) EPI (Echo Planar Imaging)
E) 3D TOF MRA
Correct Answer: D) EPI
Rationale: EPI is an extremely fast sequence that uses a single RF excitation pulse to acquire
multiple lines of K-space. Compared to FSE or STIR, which use multiple 180-degree refocusing
pulses (high RF energy), EPI generally has lower RF deposition and SAR.
Question 9
A patient requires a brain MRI but has an aneurysm clip. Which of the following metals, if used
in the clip’s construction, would make the scan "MR Unsafe"?
A) Titanium
B) Elgiloy
C) Phynox
D) 405 Stainless Steel
E) 316 Stainless Steel
Correct Answer: D) 405 Stainless Steel
Rationale: Titanium, Phynox, Elgiloy, and 316 Stainless Steel are generally considered non-
ferromagnetic (non-ferrous). However, 405 Stainless Steel and 17-7PH Stainless Steel are
ferromagnetic and would pose a significant risk of torque and displacement.
, 4
Question 10
Which of the following statements regarding Lenz’s Force is correct?
A) It only affects ferromagnetic objects like iron.
B) It occurs when an electrically conductive (but non-ferrous) object moves through a strong
magnetic field.
C) It is independent of the field strength.
D) It decreases as the speed of motion increases.
E) It attracts objects toward the isocenter.
Correct Answer: B) It occurs when an electrically conductive (but non-ferrous) object moves
through a strong magnetic field.
Rationale: Lenz's Law describes eddy currents induced in conductive materials (like aluminum
or copper) as they move through the Bo field. These currents create a magnetic field that opposes
the motion, resulting in a "drag" or "repulsive" force.
Question 11
If an MRI scanner is operating in "Normal Operating Mode," the Whole-Body Specific
Absorption Rate (SAR) must not exceed:
A) 1 W/kg
B) 2 W/kg
C) 4 W/kg
D) 8 W/kg
E) 10 W/kg
Correct Answer: B) 2 W/kg
Rationale: Normal Operating Mode is the mode in which none of the outputs have a value that
would cause physiological stress to patients. The limit is 2 W/kg. First-Level Controlled Mode
allows up to 4 W/kg.
Question 12
An "MR Conditional" labeling for an implant must specify parameters for which of the
following?
A) Static magnetic field (Bo) only
B) RF fields (B1) only
C) Switched gradient fields (dB/dt) only
D) Static field, RF fields, and Spatial Gradient fields
E) Only the weight of the patient
Correct Answer: D) Static field, RF fields, and Spatial Gradient fields
Rationale: MR Conditional means an item has been demonstrated to pose no known hazards in a
specified MR environment under specific conditions, which must include the field strength, the
maximum spatial gradient, and the SAR limits.
