ARRT MRI exam review 2024 COMPLETE
EXAM QUESTIONS AND VERIFIED
ANSWERS| 100% ACCURATE
SOLUTIONS|ALREADY GRADED A+
what is the most abundant element in the human body? - ✔️✔️hydrogen
nuclei that are available for MRI are those that exhibit a _________ - ✔️✔️net spin
low energy = spin up = _______ - ✔️✔️parallel
high energy = spin down = __________ - ✔️✔️antiparallel
thermal equilibrium - ✔️✔️when the body is in the magnetic field, spins are aligned, and
nothing else has happened
B0 - ✔️✔️refers to large magnetic field of the MRI scanner
at thermal equilibrium there are a ________ portion of spins with their magnetic
moments aligned in the same direction as B0 than against it - ✔️✔️greater
the reason why SNR increases at higher field strengths is because - ✔️✔️the NMV also
increases in size the stronger B0
1 hertz = - ✔️✔️1 cycle per second
larmour equation - ✔️✔️W0 = y x B0
what do the parts of the larmor equation mean? - ✔️✔️W0 = Larmour frequency
(precessional frequency)
y = gyromagnetic ratio (42.58 MHz/T for hydrogen)
B0 = Field strength
what is the precessional frequency for hydrogen at 1.5T? - ✔️✔️63.87 MHz
(42.58 MHz/T x 1.5T)
,out of phase or incoherent - ✔️✔️magnetic moments of hydrogen are at different places
on the precessional path at a moment in time
in phase or coherent - ✔️✔️magnetic moments of hydrogen are at the same place on the
precessional path at a moment in time
what two things do you need to get signal? - ✔️✔️1) coherent
2) transverse magnetization
phase refers to - ✔️✔️the position of a magnetic moment of a spin on its precessional
path at any moment in time
B1 field is used to deliver an RF pulse which does what 2 things - ✔️✔️causes 1)
transverse magnetization
and 2) phase precession
an RF excitation pulse causes - ✔️✔️resonance
transverse magnetization occurs at __ degrees to B0 - ✔️✔️90
saturation occurs when - ✔️✔️spins are unable to absorb more energy or to be stimulated
and release more energy
what is a saturation pulse - ✔️✔️180 degree RF
dephasing and relaxation happen at the same time but are - ✔️✔️independent of
eachother
relaxation - ✔️✔️the process in which hydrogen lose energy (occurs after RF excitation
pulse is switched off)
dephasing is caused by - ✔️✔️field inhomogeneities in the B0 field and interactions
between spins and tissue
why is it called FID (free induction decay) - ✔️✔️spins FREEly precess influenced only by
B0, signal DECAYs with time, and magnetic moments of the spins INDUCE a current in
receiver coil
when RF excitation pulse is removed, the mag moments of all spins ____ and ______ -
✔️✔️dephase and produce a FID
TR (repetition time) - ✔️✔️time from application of one RF excitation pulse to the
application of the next one
, determines how much longitudinal relaxation occurs (T1 weighting)
TE (echo time) - ✔️✔️time from application of RF excitation pulse to the peak of the
signal induced in the receiver coil
determines how much decay of transverse magnetization occurs (T2 weighting)
TR controls - ✔️✔️how much T1 relaxation occurs, recovery of longitudinal magnetization
TE controls - ✔️✔️how much T2 decay occurs, decaying signal of transverse
magnetization
give examples of intrinsic contrast parameters (things that cannot be changed because
they are inherent to body's tissues) - ✔️✔️- T1 recovery time
- T2 decay time
- Proton density
- Flow
- Apparent diffusion coefficient
give examples of extrinsic contrast parameters (those that can be changed because
they are under our control) - ✔️✔️- TR
- TE
- Flip angle
- TI
- turbo factor (ETL)
- b value
describe the process of relaxation - ✔️✔️- B1 field is turned off
- hydrogen nuclei return to their low-energy state
- magnetic moments dephase
- NMV returns to B0
relaxation therefore results in the _______ longitudinal magnetization and the _____ of
transverse magnetization - ✔️✔️recovery and decay
which is faster decay or recovery? - ✔️✔️decay
T1 recovery takes ______ longer than T2 decay - ✔️✔️5-10 times longer
T1 relaxation is also known as - ✔️✔️spin lattice energy transfer
T1 recovery - ✔️✔️is the time it takes for 63% of longitudinal magnetization to recover
(intrinsic)
EXAM QUESTIONS AND VERIFIED
ANSWERS| 100% ACCURATE
SOLUTIONS|ALREADY GRADED A+
what is the most abundant element in the human body? - ✔️✔️hydrogen
nuclei that are available for MRI are those that exhibit a _________ - ✔️✔️net spin
low energy = spin up = _______ - ✔️✔️parallel
high energy = spin down = __________ - ✔️✔️antiparallel
thermal equilibrium - ✔️✔️when the body is in the magnetic field, spins are aligned, and
nothing else has happened
B0 - ✔️✔️refers to large magnetic field of the MRI scanner
at thermal equilibrium there are a ________ portion of spins with their magnetic
moments aligned in the same direction as B0 than against it - ✔️✔️greater
the reason why SNR increases at higher field strengths is because - ✔️✔️the NMV also
increases in size the stronger B0
1 hertz = - ✔️✔️1 cycle per second
larmour equation - ✔️✔️W0 = y x B0
what do the parts of the larmor equation mean? - ✔️✔️W0 = Larmour frequency
(precessional frequency)
y = gyromagnetic ratio (42.58 MHz/T for hydrogen)
B0 = Field strength
what is the precessional frequency for hydrogen at 1.5T? - ✔️✔️63.87 MHz
(42.58 MHz/T x 1.5T)
,out of phase or incoherent - ✔️✔️magnetic moments of hydrogen are at different places
on the precessional path at a moment in time
in phase or coherent - ✔️✔️magnetic moments of hydrogen are at the same place on the
precessional path at a moment in time
what two things do you need to get signal? - ✔️✔️1) coherent
2) transverse magnetization
phase refers to - ✔️✔️the position of a magnetic moment of a spin on its precessional
path at any moment in time
B1 field is used to deliver an RF pulse which does what 2 things - ✔️✔️causes 1)
transverse magnetization
and 2) phase precession
an RF excitation pulse causes - ✔️✔️resonance
transverse magnetization occurs at __ degrees to B0 - ✔️✔️90
saturation occurs when - ✔️✔️spins are unable to absorb more energy or to be stimulated
and release more energy
what is a saturation pulse - ✔️✔️180 degree RF
dephasing and relaxation happen at the same time but are - ✔️✔️independent of
eachother
relaxation - ✔️✔️the process in which hydrogen lose energy (occurs after RF excitation
pulse is switched off)
dephasing is caused by - ✔️✔️field inhomogeneities in the B0 field and interactions
between spins and tissue
why is it called FID (free induction decay) - ✔️✔️spins FREEly precess influenced only by
B0, signal DECAYs with time, and magnetic moments of the spins INDUCE a current in
receiver coil
when RF excitation pulse is removed, the mag moments of all spins ____ and ______ -
✔️✔️dephase and produce a FID
TR (repetition time) - ✔️✔️time from application of one RF excitation pulse to the
application of the next one
, determines how much longitudinal relaxation occurs (T1 weighting)
TE (echo time) - ✔️✔️time from application of RF excitation pulse to the peak of the
signal induced in the receiver coil
determines how much decay of transverse magnetization occurs (T2 weighting)
TR controls - ✔️✔️how much T1 relaxation occurs, recovery of longitudinal magnetization
TE controls - ✔️✔️how much T2 decay occurs, decaying signal of transverse
magnetization
give examples of intrinsic contrast parameters (things that cannot be changed because
they are inherent to body's tissues) - ✔️✔️- T1 recovery time
- T2 decay time
- Proton density
- Flow
- Apparent diffusion coefficient
give examples of extrinsic contrast parameters (those that can be changed because
they are under our control) - ✔️✔️- TR
- TE
- Flip angle
- TI
- turbo factor (ETL)
- b value
describe the process of relaxation - ✔️✔️- B1 field is turned off
- hydrogen nuclei return to their low-energy state
- magnetic moments dephase
- NMV returns to B0
relaxation therefore results in the _______ longitudinal magnetization and the _____ of
transverse magnetization - ✔️✔️recovery and decay
which is faster decay or recovery? - ✔️✔️decay
T1 recovery takes ______ longer than T2 decay - ✔️✔️5-10 times longer
T1 relaxation is also known as - ✔️✔️spin lattice energy transfer
T1 recovery - ✔️✔️is the time it takes for 63% of longitudinal magnetization to recover
(intrinsic)
