1|Page
ASMIRT- MRI Accreditation Actual Exam Test Bank
Newest / ASMIRT- MRI Accreditation Exam Preparation
/ASMIRT- MRI Accreditation Practice Exam With
Complete 250 Questions And Correct Detailed
Answers With Rationales |Already Graded A+(Latest
Exam Version!)
Mild sensory effects due to static magnetic fields include: -
Answer-• Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or
decrease with field strength? - 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 -
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
,2|Page
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? - 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? - 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. •
,3|Page
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? - 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
, 4|Page
• 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? - 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? -
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.
What is the greatest concern in terms of MR safety? -
Answer-RF effects are of the greatest concern in terms of
ASMIRT- MRI Accreditation Actual Exam Test Bank
Newest / ASMIRT- MRI Accreditation Exam Preparation
/ASMIRT- MRI Accreditation Practice Exam With
Complete 250 Questions And Correct Detailed
Answers With Rationales |Already Graded A+(Latest
Exam Version!)
Mild sensory effects due to static magnetic fields include: -
Answer-• Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or
decrease with field strength? - 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 -
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
,2|Page
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? - 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? - 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. •
,3|Page
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? - 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
, 4|Page
• 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? - 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? -
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.
What is the greatest concern in terms of MR safety? -
Answer-RF effects are of the greatest concern in terms of
