ASMIRT MRI Accreditation Exam Questions Version
2/2026/2027 ASMIRT MRI Accreditation prep Exam
Questions and Answers Practice Questions with
Solutions Newest | Already Graded A+|Brand New!!
How can magnetic susceptibility be used constructively in
MRI? - ANSWER-Magnetic susceptibility artefact is
commonly used to detect cerebral haemorrhage due to the
phase distortion and signal loss caused by blood break-
down products and thus susceptibility can also be used to
an advantage
How can magnetic susceptibility be reduced? - ANSWER-
The artefact can be reduced by using:
• spin-echo rather than gradient echo
• shorter TE's
,• wider bandwidths
• smaller FOV's
Why is there a precessional frequency difference between
fat and water? - ANSWER-TLDR: Fat has an electron
shield which reduces the effect of the magnetic field =
lower precessional freq.
Water doesn't have this, experiences the full effect,
precesses at a faster rate.
Chemical Shift artefact occurs because of slight
differences in the precessional frequencies of protons in
different chemical environments. In fat molecules, an
electron cloud shields the Hydrogen from the applied
,magnetic field and reduces its effect. This causes a lower
precessional frequency. This is due to the fact that fat
consists of carbon molecules bonded to hydrogen. In
water there is no such shielding due to the bonds between
hydrogen and oxygen. Thus protons experience the full
effect of the applied magnetic field and precess at a faster
rate.
What is the precessional frequency difference between fat
and water at 1.5T? - ANSWER-The difference in
precessional frequencies increases with field strength and
is in the order of 3.5 parts per million. At 1.5 Tesla this
difference is: 64 MHz x 3.5/1,000,000 = 224 Hz.
, What is the appearance of chemical shift artefact? -
ANSWER-Since frequency is used to spatially encode an
image, this difference will cause spatial errors to occur
during the image reconstruction process. On the image,
this artefact will appear in the frequency direction as a
bright band of signal at the low frequency side and a void
at the high frequency side of a fat-water interface.
Given the following calculate chemical shift:
Receiver BW of 32kHz
Image matrix of 256
20cm FOV - ANSWER-A receiver bandwidth of 32 kHz
and a 256 image matrix will produce a frequency range
across each pixel of 32,000 ÷ 256 = 125 Hz. The chemical
shift in this case will be: 224 ÷ 125 = 1.8 pixels. At a 20 cm
2/2026/2027 ASMIRT MRI Accreditation prep Exam
Questions and Answers Practice Questions with
Solutions Newest | Already Graded A+|Brand New!!
How can magnetic susceptibility be used constructively in
MRI? - ANSWER-Magnetic susceptibility artefact is
commonly used to detect cerebral haemorrhage due to the
phase distortion and signal loss caused by blood break-
down products and thus susceptibility can also be used to
an advantage
How can magnetic susceptibility be reduced? - ANSWER-
The artefact can be reduced by using:
• spin-echo rather than gradient echo
• shorter TE's
,• wider bandwidths
• smaller FOV's
Why is there a precessional frequency difference between
fat and water? - ANSWER-TLDR: Fat has an electron
shield which reduces the effect of the magnetic field =
lower precessional freq.
Water doesn't have this, experiences the full effect,
precesses at a faster rate.
Chemical Shift artefact occurs because of slight
differences in the precessional frequencies of protons in
different chemical environments. In fat molecules, an
electron cloud shields the Hydrogen from the applied
,magnetic field and reduces its effect. This causes a lower
precessional frequency. This is due to the fact that fat
consists of carbon molecules bonded to hydrogen. In
water there is no such shielding due to the bonds between
hydrogen and oxygen. Thus protons experience the full
effect of the applied magnetic field and precess at a faster
rate.
What is the precessional frequency difference between fat
and water at 1.5T? - ANSWER-The difference in
precessional frequencies increases with field strength and
is in the order of 3.5 parts per million. At 1.5 Tesla this
difference is: 64 MHz x 3.5/1,000,000 = 224 Hz.
, What is the appearance of chemical shift artefact? -
ANSWER-Since frequency is used to spatially encode an
image, this difference will cause spatial errors to occur
during the image reconstruction process. On the image,
this artefact will appear in the frequency direction as a
bright band of signal at the low frequency side and a void
at the high frequency side of a fat-water interface.
Given the following calculate chemical shift:
Receiver BW of 32kHz
Image matrix of 256
20cm FOV - ANSWER-A receiver bandwidth of 32 kHz
and a 256 image matrix will produce a frequency range
across each pixel of 32,000 ÷ 256 = 125 Hz. The chemical
shift in this case will be: 224 ÷ 125 = 1.8 pixels. At a 20 cm
