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ASMIRT MRI Accreditation Exam
2026- complete questions with
correct detailed solutions
Mild sensory effects due to static magnetic fields include: - correct-answer -•
Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or decrease with field
strength? - correct-answer -Sensory effects are related to the strength of the
magnetic field with few symptoms at 1.5T and more appearing approaching a 4T
field strength
Explain what t-wave artefact is and why it occurs - correct-answer -Any charged
particle moving through a magnetic field will have a current induced via this
interaction. As blood, a conductive fluid flows through a magnetic field it induces
an electrical biopotential. This electrical biopotential can be seen on the ECG
waveform of patients in MRI. It is demonstrated by an increase in the T-wave
amplitude on ECG. This change in T-wave amplitude is directly proportional to the
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strength of the Static Filed. It is important that MR radiographers are aware of this
as elevated T-waves are also associated with ischemia and myocardial infarction.
What risks does the static magnetic field pose in terms of implants and objects? -
correct-answer -Static Fields also pose hazards through the displacement of ferro-
magnetic implants and objects. The static field imparts both a translation
(attractive force) and a torque (twisting force). The strong nature of the Static
Field also has the potential to disrupt the function of Cardiac Pacemakers. Anyone
entering beyond the 5G line should be screened for contraindications to strong
Magnetic Fields. Also be aware of what is being taken over the 5G line.
What strategies can be employed to reduce the risks of the static magnetic field
impacting on implants and objects? - correct-answer -• Ferromagnetic objects
may become airborne - 40 km/hr terminal velocity possible at 1.5T
• Test any metal objects with a hand held magnet before allowing them to enter
the room.
• Keep the general public behind the 5G line. •
Possible contra-indications include pacemakers, aneurysm clips, intra-vascular
coils and stents, heart valves, penile implants, cochlear implants, ocular implants
(Fatio eyelid springs), neuro stimulators, bone growth stimulators, drug infusion
pumps.
What effect do gradient magnetic fields have on patient safety? - correct-answer -
Faraday's Law dictates that changing magnetic fields will generate a voltage and a
current in a conductor. The switching of the gradients induces electrical currents
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in conductive tissues. Voltage generation will occur during the rise and fall times -
ie. while the field is changing. The largest voltages will be generated at the
periphery where the gradient amplitudes are highest. The most common result of
these voltages is Peripheral Nerve Stimulation (PNS). Other side-effects are listed
below;
• magnetophosphenes - electromagnetically induced flashes of light
• seizures
• tissue heating
• peripheral nerve stimulation
• muscle contractions
• cardiac arrhythmias
• some degree of patient heating has been shown to be a result of Gradient
Magnetic effects. However, this has been shown to be so low as to be negligible
What strategies can be employed to keep gradient effects to a minimum? -
correct-answer -In order to keep these effects to a minimum the following is
recommended.
• keep dB/dT less than those required to produce peripheral nerve stimulation.
• max limit for dB/dT of 6 Tesla / sec
What is the cause of acoustic noise during an MRI scan? - correct-answer -The
characteristic noise that is heard during an MRI scan is the result of the interaction
of Lorentz forces generated by the Gradient Coil when a current is pulsed through
them in the presence of a Static Magnetic Field. The noise results as these forces
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are so strong as to twist the coils on their mounts. In some cases this can be in
excess of 100dB particularly when running EPI sequences. Thus all patients need
to be provided hearing protection.
What is the greatest concern in terms of MR safety? - correct-answer -RF effects
are of the greatest concern in terms of MR safety. The main effect is the
deposition of energy resulting in tissue heating. Of particular concern are heat
sensitive organs such as the eyes and testes. One of the major concerns is where a
patient has a metallic implant which results in greater heating.
RF field safety concerns increase or decrease with increasing field strength> -
correct-answer -The amount of energy absorbed will increase with frequency of
the RF field delivered and is therefore greater at higher field strengths
What is SAR? - correct-answer -SAR= Specific Absorption Rate - the term used to
describe energy dissipation
SAR is expressed in: - correct-answer -Watts / kg
SAR will depend on factors including: - correct-answer -• frequency (& therefore
the field strength)
ASMIRT MRI Accreditation Exam
2026- complete questions with
correct detailed solutions
Mild sensory effects due to static magnetic fields include: - correct-answer -•
Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or decrease with field
strength? - correct-answer -Sensory effects are related to the strength of the
magnetic field with few symptoms at 1.5T and more appearing approaching a 4T
field strength
Explain what t-wave artefact is and why it occurs - correct-answer -Any charged
particle moving through a magnetic field will have a current induced via this
interaction. As blood, a conductive fluid flows through a magnetic field it induces
an electrical biopotential. This electrical biopotential can be seen on the ECG
waveform of patients in MRI. It is demonstrated by an increase in the T-wave
amplitude on ECG. This change in T-wave amplitude is directly proportional to the
,2|Page
strength of the Static Filed. It is important that MR radiographers are aware of this
as elevated T-waves are also associated with ischemia and myocardial infarction.
What risks does the static magnetic field pose in terms of implants and objects? -
correct-answer -Static Fields also pose hazards through the displacement of ferro-
magnetic implants and objects. The static field imparts both a translation
(attractive force) and a torque (twisting force). The strong nature of the Static
Field also has the potential to disrupt the function of Cardiac Pacemakers. Anyone
entering beyond the 5G line should be screened for contraindications to strong
Magnetic Fields. Also be aware of what is being taken over the 5G line.
What strategies can be employed to reduce the risks of the static magnetic field
impacting on implants and objects? - correct-answer -• Ferromagnetic objects
may become airborne - 40 km/hr terminal velocity possible at 1.5T
• Test any metal objects with a hand held magnet before allowing them to enter
the room.
• Keep the general public behind the 5G line. •
Possible contra-indications include pacemakers, aneurysm clips, intra-vascular
coils and stents, heart valves, penile implants, cochlear implants, ocular implants
(Fatio eyelid springs), neuro stimulators, bone growth stimulators, drug infusion
pumps.
What effect do gradient magnetic fields have on patient safety? - correct-answer -
Faraday's Law dictates that changing magnetic fields will generate a voltage and a
current in a conductor. The switching of the gradients induces electrical currents
,3|Page
in conductive tissues. Voltage generation will occur during the rise and fall times -
ie. while the field is changing. The largest voltages will be generated at the
periphery where the gradient amplitudes are highest. The most common result of
these voltages is Peripheral Nerve Stimulation (PNS). Other side-effects are listed
below;
• magnetophosphenes - electromagnetically induced flashes of light
• seizures
• tissue heating
• peripheral nerve stimulation
• muscle contractions
• cardiac arrhythmias
• some degree of patient heating has been shown to be a result of Gradient
Magnetic effects. However, this has been shown to be so low as to be negligible
What strategies can be employed to keep gradient effects to a minimum? -
correct-answer -In order to keep these effects to a minimum the following is
recommended.
• keep dB/dT less than those required to produce peripheral nerve stimulation.
• max limit for dB/dT of 6 Tesla / sec
What is the cause of acoustic noise during an MRI scan? - correct-answer -The
characteristic noise that is heard during an MRI scan is the result of the interaction
of Lorentz forces generated by the Gradient Coil when a current is pulsed through
them in the presence of a Static Magnetic Field. The noise results as these forces
, 4|Page
are so strong as to twist the coils on their mounts. In some cases this can be in
excess of 100dB particularly when running EPI sequences. Thus all patients need
to be provided hearing protection.
What is the greatest concern in terms of MR safety? - correct-answer -RF effects
are of the greatest concern in terms of MR safety. The main effect is the
deposition of energy resulting in tissue heating. Of particular concern are heat
sensitive organs such as the eyes and testes. One of the major concerns is where a
patient has a metallic implant which results in greater heating.
RF field safety concerns increase or decrease with increasing field strength> -
correct-answer -The amount of energy absorbed will increase with frequency of
the RF field delivered and is therefore greater at higher field strengths
What is SAR? - correct-answer -SAR= Specific Absorption Rate - the term used to
describe energy dissipation
SAR is expressed in: - correct-answer -Watts / kg
SAR will depend on factors including: - correct-answer -• frequency (& therefore
the field strength)
