ARRT MRI STUDY GUIDE QUESTIONS WITH ALL
CORRECT ANSWERS VERIFIED.
⫸ T2 decay time. Answer:the time it takes for 63% of the coherent transverse magnetization to
decay in a tissue
⫸ T2 contrast. Answer:an image where fat is hypointense and water is relatively hyperintense
because the TE is long enough to allow full dephasing
⫸ T2 weighting. Answer:an image whose contrast is predominantly due to the differences in
the T2 decay times of the tissues
⫸ diffusion. Answer:describes the movement of molecules int he extracellular space due to
random thermal motion
⫸ describe ADC. Answer:intrinsic contrast parameter, net displacement of molecules diffusing
across an area per second
⫸ how does diffusion weighting work?. Answer:application of two RF gradients, one to
dephase, and then one to rephase them
where ADC is low molecules are stationary, and high signal is obtained
where ADC is high, molecules are moving, and low signal is obtained
⫸ define b value/factor. Answer:Extrinsic contrast parameter that controls the ADC of the
tissue and it's strength, duration, and interval of gradients is known as b value or factor
⫸ what parameter controls functional MRI. Answer:BOLD
blood oxygen level dependent
,⫸ functional imaging is used to. Answer:image the function or physiology of a system rather
than its anatomy
⫸ what is the recommended dosage of gadolinium?. Answer:0.1 millimole per kilogram of body
weight
⫸ what are the two ways you can rephasing magnetic moments of nuclei to produce an echo?.
Answer:- using an additional 180 RF pulse
- using gradients
⫸ describe the steps in a spin echo pulse sequence. Answer:uses 90 RF excitation pulse to flip
NMV fully into transverse plane, FID occurs after excitation pulse, T2* dephasing occurs, after
tau (1/2 TE) another pulse, commonly 180 RF, is used to compensate for this dephasing and
refocus nuclei
⫸ how is T2* dephasing eliminated?. Answer:by the 180 RF rephasing pulse that "flips" the
dephasing vectors so the slower ones catch up to the faster ones all at the same point and
maximum signal is induced
⫸ how do spin echoes give true T2 weighting?. Answer:180 RF pulse compensates for field
inhomogeneities and therefore eliminates T2*
⫸ What is the relationship between TE and tau in spin echo pulse sequence. Answer:tau = 1/2
TE
the tau times the 180 refocusing pulse so that the nuclei will rephase in time for the TE
⫸ conventional spin echo. Answer:uses 90 RF excitation pulse followed by one or more 180 RF
rephasing pulses to generate one or more spin echoes
⫸ T2 decay. Answer:the decay of coherent transverse magnetization due to spin-spin relaxation
after the RF excitation pulse is switched off
⫸ how are spoiler gradients used in conventional spin echoes. Answer:applied at the end of
each TR period to ensure that there is no coherent transverse magnetization at the beginning of
the next repetition
⫸ what weighting is produced by a spin echo using one echo. Answer:T1 weighting
,⫸ what weighting is produced by a spin echo using two echoes. Answer:PD and T2 in the same
TR period
⫸ what pulse sequence is the gold standard. Answer:spin echo because they produce
understood and predictable contrast
⫸ what kind of weighting can be produced by a conventional spin echo technique. Answer:T1,
T2, and PD
⫸ how are fast spin echoes produced?. Answer:by filling k space more efficiently, more than
one line per TR
⫸ define turbo factor or ETL (echo train length). Answer:the number of 180 RF rephasing
pulses performed every TR corresponds to the number of echoes produced and the number of
lines of k space filled with data from echoes
⫸ what is the scan time equation. Answer:scan time = (TR x phase matrix x NEX) / ETL
⫸ what is j coupling?. Answer:Intrinsic shortening of T2 signal constant in lipids, disappears in
FSE, which causes T2 fat signal to appear brighter on FSE.
⫸ what happens to metal artifacts in FSE sequences. Answer:they are significantly reduced
because of the repeated 180 RF pulses compensate for field inhomogeneities
⫸ what weighting can you achieve with FSE/TSE?. Answer:T1 (with shorter ETLs)
PD
T2
⫸ long turbo factors (ETLs) is associated with ____ weighting. Answer:T2
⫸ FSE involve applying the ______ multiple times in a TR period at varying amplitudes and
polarity. Answer:phase encoding gradient
⫸ image weighting in a FSE/TSE is determined by selecting a _______. Answer:effective TE
, ⫸ define single shot turbo spin echoes (SS-FSE). Answer:have even shorter scan times than
FSE/TSE because they fill all lines of k-space at once
combines partial fourier technique with FSE, menaing half the lines of k-space are filled in one
TR and the other half are transposed
⫸ driven equilibrium uses what techniques. Answer:a reverse flip angle excitation pulse
applied at the end of the echo train so that any transverse magnetization is flipped in to the
longitudinal plane and available for excitation at the beginning of the next TR
⫸ a 180 RF pulse requires ____ times more energy than a 90 RF pulse. Answer:4
⫸ inversion recovery sequences begin with a. Answer:180 RF pulse before the excitation pulse
⫸ give examples of intrinsic contrast parameters (things that cannot be changed because they are
inherent to body's tissues). Answer:- 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). Answer:- TR
- TE
- Flip angle
- TI
- turbo factor (ETL)
- b value
⫸ describe the process of relaxation. Answer:- B1 field is turned off
- hydrogen nuclei return to their low-energy state
- magnetic moments dephase
CORRECT ANSWERS VERIFIED.
⫸ T2 decay time. Answer:the time it takes for 63% of the coherent transverse magnetization to
decay in a tissue
⫸ T2 contrast. Answer:an image where fat is hypointense and water is relatively hyperintense
because the TE is long enough to allow full dephasing
⫸ T2 weighting. Answer:an image whose contrast is predominantly due to the differences in
the T2 decay times of the tissues
⫸ diffusion. Answer:describes the movement of molecules int he extracellular space due to
random thermal motion
⫸ describe ADC. Answer:intrinsic contrast parameter, net displacement of molecules diffusing
across an area per second
⫸ how does diffusion weighting work?. Answer:application of two RF gradients, one to
dephase, and then one to rephase them
where ADC is low molecules are stationary, and high signal is obtained
where ADC is high, molecules are moving, and low signal is obtained
⫸ define b value/factor. Answer:Extrinsic contrast parameter that controls the ADC of the
tissue and it's strength, duration, and interval of gradients is known as b value or factor
⫸ what parameter controls functional MRI. Answer:BOLD
blood oxygen level dependent
,⫸ functional imaging is used to. Answer:image the function or physiology of a system rather
than its anatomy
⫸ what is the recommended dosage of gadolinium?. Answer:0.1 millimole per kilogram of body
weight
⫸ what are the two ways you can rephasing magnetic moments of nuclei to produce an echo?.
Answer:- using an additional 180 RF pulse
- using gradients
⫸ describe the steps in a spin echo pulse sequence. Answer:uses 90 RF excitation pulse to flip
NMV fully into transverse plane, FID occurs after excitation pulse, T2* dephasing occurs, after
tau (1/2 TE) another pulse, commonly 180 RF, is used to compensate for this dephasing and
refocus nuclei
⫸ how is T2* dephasing eliminated?. Answer:by the 180 RF rephasing pulse that "flips" the
dephasing vectors so the slower ones catch up to the faster ones all at the same point and
maximum signal is induced
⫸ how do spin echoes give true T2 weighting?. Answer:180 RF pulse compensates for field
inhomogeneities and therefore eliminates T2*
⫸ What is the relationship between TE and tau in spin echo pulse sequence. Answer:tau = 1/2
TE
the tau times the 180 refocusing pulse so that the nuclei will rephase in time for the TE
⫸ conventional spin echo. Answer:uses 90 RF excitation pulse followed by one or more 180 RF
rephasing pulses to generate one or more spin echoes
⫸ T2 decay. Answer:the decay of coherent transverse magnetization due to spin-spin relaxation
after the RF excitation pulse is switched off
⫸ how are spoiler gradients used in conventional spin echoes. Answer:applied at the end of
each TR period to ensure that there is no coherent transverse magnetization at the beginning of
the next repetition
⫸ what weighting is produced by a spin echo using one echo. Answer:T1 weighting
,⫸ what weighting is produced by a spin echo using two echoes. Answer:PD and T2 in the same
TR period
⫸ what pulse sequence is the gold standard. Answer:spin echo because they produce
understood and predictable contrast
⫸ what kind of weighting can be produced by a conventional spin echo technique. Answer:T1,
T2, and PD
⫸ how are fast spin echoes produced?. Answer:by filling k space more efficiently, more than
one line per TR
⫸ define turbo factor or ETL (echo train length). Answer:the number of 180 RF rephasing
pulses performed every TR corresponds to the number of echoes produced and the number of
lines of k space filled with data from echoes
⫸ what is the scan time equation. Answer:scan time = (TR x phase matrix x NEX) / ETL
⫸ what is j coupling?. Answer:Intrinsic shortening of T2 signal constant in lipids, disappears in
FSE, which causes T2 fat signal to appear brighter on FSE.
⫸ what happens to metal artifacts in FSE sequences. Answer:they are significantly reduced
because of the repeated 180 RF pulses compensate for field inhomogeneities
⫸ what weighting can you achieve with FSE/TSE?. Answer:T1 (with shorter ETLs)
PD
T2
⫸ long turbo factors (ETLs) is associated with ____ weighting. Answer:T2
⫸ FSE involve applying the ______ multiple times in a TR period at varying amplitudes and
polarity. Answer:phase encoding gradient
⫸ image weighting in a FSE/TSE is determined by selecting a _______. Answer:effective TE
, ⫸ define single shot turbo spin echoes (SS-FSE). Answer:have even shorter scan times than
FSE/TSE because they fill all lines of k-space at once
combines partial fourier technique with FSE, menaing half the lines of k-space are filled in one
TR and the other half are transposed
⫸ driven equilibrium uses what techniques. Answer:a reverse flip angle excitation pulse
applied at the end of the echo train so that any transverse magnetization is flipped in to the
longitudinal plane and available for excitation at the beginning of the next TR
⫸ a 180 RF pulse requires ____ times more energy than a 90 RF pulse. Answer:4
⫸ inversion recovery sequences begin with a. Answer:180 RF pulse before the excitation pulse
⫸ give examples of intrinsic contrast parameters (things that cannot be changed because they are
inherent to body's tissues). Answer:- 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). Answer:- TR
- TE
- Flip angle
- TI
- turbo factor (ETL)
- b value
⫸ describe the process of relaxation. Answer:- B1 field is turned off
- hydrogen nuclei return to their low-energy state
- magnetic moments dephase
