ASMIRT - MRI Accreditation Exam Questions Version 1/ASMIRT MRI
Accreditation prep Exam Questions and Answers Practice Questions
with Solutions Newest Complete Questions And Correct Detailed
Answers| Already Graded A+
What physical law, forms the basis on MRI signal generation?
ANSWERS: According to Faraday's law of induction, a changing magnetic field
will generate a voltage in a suitably located receiver coil. This is the basis of
signal detection in MRI
,How is signal detected in MRI?
ANSWERS: For a signal to be detected, the magnetisation induced by Bo in
the direction of Bo needs to be converted into a magnetisation which
precesses in the X-Y plane. This is done by applying a RF pulse (B1) that causes
the NMV to flip and precess in the transverse plane. NMV will precess about
B1 which can be pulsed for as long as it takes to rotate the magnetisation
through 90 degrees into the transverse plane. Individual protons will now be
precessing in phase to produce a rotating magnetisation which can be
detected with a receiver coil.
, What happens to MRI signal over time and what is this called?
ANSWERS: When a scanning sequence starts, the magnetisation in the
longitudinal plane is flipped into the transverse plane using an RF pulse. This
creates a measurable signal in the receiver coil. Over time this signal fades
away or decays. This is known as relaxation of the signal. After the RF pulse,
the NMV moves back towards the longitudinal plane via two relaxation
processes.
What are the two types of relaxation in MRI?
ANSWERS:
• Spin-Lattice Relaxation, T1 Relaxation
• Spin-Spin Relaxation, T2 Relaxation or T2 decay
, What is T1 relaxation?
ANSWERS: T1 relaxation is commonly referred to as spin-lattice relaxation as
the interactions that are involved in this relaxation mechanism are between
the protons (or spins) and their environment. This type of relaxation deals
with the longitudinal component of the magnetisation and T1 is a measure of
the time in which it takes the longitudinal component of magnetisation to
reach 63% of its initial value.
Accreditation prep Exam Questions and Answers Practice Questions
with Solutions Newest Complete Questions And Correct Detailed
Answers| Already Graded A+
What physical law, forms the basis on MRI signal generation?
ANSWERS: According to Faraday's law of induction, a changing magnetic field
will generate a voltage in a suitably located receiver coil. This is the basis of
signal detection in MRI
,How is signal detected in MRI?
ANSWERS: For a signal to be detected, the magnetisation induced by Bo in
the direction of Bo needs to be converted into a magnetisation which
precesses in the X-Y plane. This is done by applying a RF pulse (B1) that causes
the NMV to flip and precess in the transverse plane. NMV will precess about
B1 which can be pulsed for as long as it takes to rotate the magnetisation
through 90 degrees into the transverse plane. Individual protons will now be
precessing in phase to produce a rotating magnetisation which can be
detected with a receiver coil.
, What happens to MRI signal over time and what is this called?
ANSWERS: When a scanning sequence starts, the magnetisation in the
longitudinal plane is flipped into the transverse plane using an RF pulse. This
creates a measurable signal in the receiver coil. Over time this signal fades
away or decays. This is known as relaxation of the signal. After the RF pulse,
the NMV moves back towards the longitudinal plane via two relaxation
processes.
What are the two types of relaxation in MRI?
ANSWERS:
• Spin-Lattice Relaxation, T1 Relaxation
• Spin-Spin Relaxation, T2 Relaxation or T2 decay
, What is T1 relaxation?
ANSWERS: T1 relaxation is commonly referred to as spin-lattice relaxation as
the interactions that are involved in this relaxation mechanism are between
the protons (or spins) and their environment. This type of relaxation deals
with the longitudinal component of the magnetisation and T1 is a measure of
the time in which it takes the longitudinal component of magnetisation to
reach 63% of its initial value.
