ASMIRT- MRI Accreditation Actual Exam Test Bank
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
|ALREADY GRADED A+(NEWEST VERSION!)
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
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.
1|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
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)
• 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? - Correct Answer-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? - Correct Answer-• Maximum
SAR of 0.4 W/kg (whole body)
• 3.2 W/kg (head)
• 8.0 W/kg (in any one gram of tissue)
2|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
• RF exposure should be insufficient to produce a core temperature increase of 1
degree C
Why is patient heating a concern in MRI? - Correct Answer-• 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? - Correct Answer-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
How can patient burns be avoided? - Correct Answer-• use only equipment tested
to be MR compatible
• allow only MR trained staff to use the equipment
• check the integrity of the electrical insulation of all cables
3|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
• remove all unnecessary electrically conductive equipment from the bore
• keep electrically conductive equipment from directly contacting the patient
• keep electrically conductive equipment from forming large diameter conductive
loops
• position cables to avoid cross points
• position ECG cables to exit down the centre of the bore
• do not allow contact between the patient's skin and the magnet bore
Explain the deleterious effects of MRI on pregnant patients - Correct Answer-
There are no known biological effects of MRI on foetuses. MR imaging may be
used in pregnant women if other non-ionizing forms of diagnostic imaging are
inadequate or if the examination provides important information that would
otherwise require exposure to ionizing radiation (e.g., fluoroscopy, CT, etc.).
Pregnant patients should be informed that, to date, there has been no indication
that the use of clinical MR imaging during pregnancy has produced deleterious
effects." This policy has been adopted by the American College of Radiology and is
considered to be the "standard of care" with respect to the use of MRI procedures
in pregnant patients. Importantly, this information applies to MR systems
operating up to and including 3-Tesla. (MR Imaging Safety and Patient
Management issued by the Safety Committee of the Society for Magnetic
Resonance Imaging) Pregnant patients should be reviewed on a case by case basis
to assess whether the risks outweigh the potential benefits.
Can pregnant staff enter the MRI environment? - Correct Answer-No increased
incidence of spontaneous abortion has been demonstrated among MR
radiographers or nurses. The most common policy seems to be that pregnant staff
are allowed exposure to the static field (ie. to set patients up) but leave the room
during image acquisition to avoid exposure to RF and gradient fields.
4|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
|ALREADY GRADED A+(NEWEST VERSION!)
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
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.
1|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
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)
• 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? - Correct Answer-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? - Correct Answer-• Maximum
SAR of 0.4 W/kg (whole body)
• 3.2 W/kg (head)
• 8.0 W/kg (in any one gram of tissue)
2|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
• RF exposure should be insufficient to produce a core temperature increase of 1
degree C
Why is patient heating a concern in MRI? - Correct Answer-• 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? - Correct Answer-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
How can patient burns be avoided? - Correct Answer-• use only equipment tested
to be MR compatible
• allow only MR trained staff to use the equipment
• check the integrity of the electrical insulation of all cables
3|Page
, ASMIRT- MRI Accreditation Actual Exam Test Bank
• remove all unnecessary electrically conductive equipment from the bore
• keep electrically conductive equipment from directly contacting the patient
• keep electrically conductive equipment from forming large diameter conductive
loops
• position cables to avoid cross points
• position ECG cables to exit down the centre of the bore
• do not allow contact between the patient's skin and the magnet bore
Explain the deleterious effects of MRI on pregnant patients - Correct Answer-
There are no known biological effects of MRI on foetuses. MR imaging may be
used in pregnant women if other non-ionizing forms of diagnostic imaging are
inadequate or if the examination provides important information that would
otherwise require exposure to ionizing radiation (e.g., fluoroscopy, CT, etc.).
Pregnant patients should be informed that, to date, there has been no indication
that the use of clinical MR imaging during pregnancy has produced deleterious
effects." This policy has been adopted by the American College of Radiology and is
considered to be the "standard of care" with respect to the use of MRI procedures
in pregnant patients. Importantly, this information applies to MR systems
operating up to and including 3-Tesla. (MR Imaging Safety and Patient
Management issued by the Safety Committee of the Society for Magnetic
Resonance Imaging) Pregnant patients should be reviewed on a case by case basis
to assess whether the risks outweigh the potential benefits.
Can pregnant staff enter the MRI environment? - Correct Answer-No increased
incidence of spontaneous abortion has been demonstrated among MR
radiographers or nurses. The most common policy seems to be that pregnant staff
are allowed exposure to the static field (ie. to set patients up) but leave the room
during image acquisition to avoid exposure to RF and gradient fields.
4|Page
