ASMIRT – MRI Accreditation Exam
ASMIRT – MRI ACCREDITATION EXAM NEWEST 2025/2026
STUDY GUIDE EXAM COMPLETE 300 QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED
A+||BRAND NEW VERSION!!
What strategies can be employed to keep gradient effects to a minimum?
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?
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?
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>
1|Page
, ASMIRT – MRI Accreditation Exam
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?
SAR= Specific Absorption Rate - the term used to describe energy dissipation
SAR is expressed in:
Watts / kg
SAR will depend on factors including:
• frequency (& therefore the field strength)
• RF pulse - where power deposited is proportional to (flip angle / 90)
• TR
• RF coil - transmit / receive or receive only
• volume of tissue within the coil
• conductivity of the tissue
What determines the SAR calculation?
The SAR is calculated for each sequence on the basis of the sequence parameters
and the patient weight
What are the FDA recommendations regarding SAR?
• Maximum SAR of 0.4 W/kg (whole body)
• 3.2 W/kg (head)
• 8.0 W/kg (in any one gram of tissue)
• RF exposure should be insufficient to produce a core temperature increase of 1
degree C
2|Page
, ASMIRT – MRI Accreditation Exam
Why is patient heating a concern in MRI?
• Heating will also vary with the state of the patient's thermo-regulatory system,
the ambient temperature, the humidity and the air flow around the patient.
• The eye and the testes are particularly sensitive organs due to a low capacity for
heat dissipation.
• Excessive RF exposure and temperature increase can lead to an increase in
blood pressure and heart rate.
A SAR warning appears during a scan preventing you from continuing with an
examination unless factors are altered to a safe level, what can be changed in
order to achieve this?
Factors which will reduce SAR if required include:
• reducing the number of slices
• reducing the ETL
• increasing the TR
• GE rather than SE
• Use quadrature coils rather than linear coils for transmission
• Change to low SAR sequence design
Mild sensory effects due to static magnetic fields include:
• Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or decrease with field
strength?
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
3|Page
, ASMIRT – MRI Accreditation Exam
Explain what t-wave artefact is and why it occurs
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?
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?
• 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?
4|Page
ASMIRT – MRI ACCREDITATION EXAM NEWEST 2025/2026
STUDY GUIDE EXAM COMPLETE 300 QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) |ALREADY GRADED
A+||BRAND NEW VERSION!!
What strategies can be employed to keep gradient effects to a minimum?
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?
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?
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>
1|Page
, ASMIRT – MRI Accreditation Exam
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?
SAR= Specific Absorption Rate - the term used to describe energy dissipation
SAR is expressed in:
Watts / kg
SAR will depend on factors including:
• frequency (& therefore the field strength)
• RF pulse - where power deposited is proportional to (flip angle / 90)
• TR
• RF coil - transmit / receive or receive only
• volume of tissue within the coil
• conductivity of the tissue
What determines the SAR calculation?
The SAR is calculated for each sequence on the basis of the sequence parameters
and the patient weight
What are the FDA recommendations regarding SAR?
• Maximum SAR of 0.4 W/kg (whole body)
• 3.2 W/kg (head)
• 8.0 W/kg (in any one gram of tissue)
• RF exposure should be insufficient to produce a core temperature increase of 1
degree C
2|Page
, ASMIRT – MRI Accreditation Exam
Why is patient heating a concern in MRI?
• Heating will also vary with the state of the patient's thermo-regulatory system,
the ambient temperature, the humidity and the air flow around the patient.
• The eye and the testes are particularly sensitive organs due to a low capacity for
heat dissipation.
• Excessive RF exposure and temperature increase can lead to an increase in
blood pressure and heart rate.
A SAR warning appears during a scan preventing you from continuing with an
examination unless factors are altered to a safe level, what can be changed in
order to achieve this?
Factors which will reduce SAR if required include:
• reducing the number of slices
• reducing the ETL
• increasing the TR
• GE rather than SE
• Use quadrature coils rather than linear coils for transmission
• Change to low SAR sequence design
Mild sensory effects due to static magnetic fields include:
• Vertigo
• Nausea
• Taste Sensations
Sensory effects of the static magnetic field increase or decrease with field
strength?
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
3|Page
, ASMIRT – MRI Accreditation Exam
Explain what t-wave artefact is and why it occurs
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?
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?
• 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?
4|Page
