ASMIRT - MRI Accreditation Exam Latest
2025/2026 Questions and Correct Answers
Graded A+|Assured Success
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 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.
,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
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 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 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
2025/2026 Questions and Correct Answers
Graded A+|Assured Success
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 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.
,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
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 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 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
