ASMRIT MRI ACCREDITATION EXAM
VERSION 1 2026/2027 WITH ACTUAL
CORRECT QUESTIONS AND VERIFIED
DETAILED ANSWERS |CURRENTLY TESTING
QUESTIONS AND SOLUTIONS|ALREADY
GRADED A+|NEWEST |BRAND NEW
VERSION!!| |LATEST UPDATE
What is FLAIR?
Fluid Attenuation Inversion Recovery
'FLAIR' to suppress the signal from CSF with a TI of around 2200mSec at 1.5 Tesla.
What are gradient echo sequences?
Gradient echo sequences use low flip angles, this means T1 recovery will take less time and
shorter TR intervals are possible. Without the 180 degree pulse, shorter TE times are also
possible. Short TR and TE times allow rapid signal acquisition and so GRE sequences form the
basis of many rapid imaging scans such as breath-hold studies and MRA. The signal is refocussed
using a rephasing gradient.
How does TR and TE affect image weighting in GE imaging?
Like spin echo imaging the basic rules for TR and TE still apply. That being short TR and TE for T1
weighting and Long TR and TE for T2 weighting, however the actual values of TR and TE drop
considerably in GRE imaging due to the fact that we use a variable flip angle no longer the 90
degrees that is used in SE imaging.
What are some disadvantages of GE sequences?
With no 180 degree pulse, unfortunately GRE sequences are very sensitive to magnetic field
inhomogeneities. This may result in unwanted susceptibility artefacts at eg. tissue-air interfaces.
1|Page
,Due to the lack of a 180 degree refocusing pulse T2 contrast in GRE imaging is referred to as T2*
contrast as dephasing due to inhomogeneity will affect the image contrast.
What are the key differences between SE and GRE imaging?
SPIN ECHO
▪ 90 excitation pulse transfers all available Mz into the transverse plane.
▪ 180 refocusing pulse gives largest possible signal▪ Therefore high SNR and reduced
inhomogeneity artefact
▪ Long scan time
GRADIENT ECHO
▪ Utilises a gradient reversal to rephase spins
▪ Reduced flip angle therefore less signal in Mxy plane
▪ No 180 refocusing therefore susceptibility artefacts
▪ Lower SNR
▪ Shorter scan time
To achieve T1 weighting in a GRE sequence, what parameters should be set?
• T1 Weighting in GRE
Large Flip angle 70-110 degrees
Short TE 5-10ms
Short TR < 50ms
To achieve T2 weighting in a GRE sequence, what parameters should be set?
T2* Weighting in GRE
Small flip angle 5-20 degrees
Long TE 15-25ms
Short TR minimum possible depending on number of slices as the small flip angle ensures rapid
T1 recovery
To achieve PD weighting in a GRE sequence, what parameters should be set?
2|Page
,PD Weighting in GRE Small flip angle 5-20 degrees Short TE 5-10ms Short TR minimum possible
depending on number of slices as the small flip angle ensures rapid T1 recovery
What is steady state?
This is the condition that applies when the TR used is shorter than the T1 and the T2 of the
tissue. There will not be enough time for the transverse magnetisation to have decayed away
before the next RF pulse is applied. Each RF pulse produces a FID, each pair of pulses produces a
Hahn echo, and stimulated echoes arise from each set of three or more pulses. If the TR is short
enough, the tails of the FID's and the spin echoes merge to produce a continuous signal of
varying amplitude. The signal contains both FID and spin-echo components, with the TR being
equal to the TAU of the spin-echo
Explain how the residual transverse magnetisation is can be removed in a steady state
sequence?
The use of short TR intervals creates the steady state condition, but with these sequences the
residual transverse magnetisation is deliberately removed or 'spoiled' before the next excitation
pulse. Spoiling is done by;
• Gradient spoiling, where a gradient of varying amplitude is turned on just before the next RF
pulse. (Siemens' Flash)
• RF spoiling, where the phase of the RF is changed with each excitation and the receiver locks
on only to the phase of the preceding pulse. (GE's SPGR
What are gradient echo incoherent/spoiled gradient echo sequences usually used to for in
terms of weighting
These sequences are used to produce rapid T1 weighted images. eg. breath-hold liver studies.
Only the FID is re-phased - the spin-echo is spoiled and not sampled.
For GRE incoherent T1 weighted scans the following parameters are suggested
3|Page
, •Flip angle 30-45 degree
•Short TE : minimum possible: often two are used for in and out of phase (minimum TE ensures
minimal T2*) •Short TR : 20-50ms
How is a coherent gradient echo sequence acheived?
Short TR values ensure that the steady state is achieved with these sequences. The transverse
magnetisation left over at the time of the next excitation pulse is kept coherent using a re-
winder gradient after readout. This compensates for the dephasing which occurs due to the
phase encoding process.
What are coherent gradient echo sequences used to determine?
Coherent gradient echo pulse sequences produce images that are T2* weighted. They can be
used to determine if a vessel is patent or if a region contains fluid.
For GRE coherent T2* weighted scans the following parameters are suggested
For GRE coherent T2* weighted scans the following parameters are suggested
•Flip angle 30-45 degree
•Long TE: 15ms+ (this maximises T2* contrast)
•Short TR : 20-50ms
What is an EPI sequence and what do they achieve?
With echo planar imaging, a single echo train is used to collect data from all lines of K-space
during on TR period. Use of this technique subsequently considerably shortens the acquisition
time. There are two types of EPI sequences; SE and GRE sequences. All the lines of K-space can
be acquired in a single TR (in single shot EPI) or in two or more TR's. (in multishot EPI) The phase
and frequency encoding gradients are turned on and off very rapidly, a technique which allows
the rapid filling of K-space. EPI imaging is the sequence of choice for diffusion weighted imaging,
for which a EPI SE sequence is typically used. EPI imaging is more vulnerable to magnetic
susceptibility effects and provides greater tissue contrast than does imaging with standard GRE
sequences. EPI imaging sequences are widely used to assess cerebral perfusion.
4|Page
VERSION 1 2026/2027 WITH ACTUAL
CORRECT QUESTIONS AND VERIFIED
DETAILED ANSWERS |CURRENTLY TESTING
QUESTIONS AND SOLUTIONS|ALREADY
GRADED A+|NEWEST |BRAND NEW
VERSION!!| |LATEST UPDATE
What is FLAIR?
Fluid Attenuation Inversion Recovery
'FLAIR' to suppress the signal from CSF with a TI of around 2200mSec at 1.5 Tesla.
What are gradient echo sequences?
Gradient echo sequences use low flip angles, this means T1 recovery will take less time and
shorter TR intervals are possible. Without the 180 degree pulse, shorter TE times are also
possible. Short TR and TE times allow rapid signal acquisition and so GRE sequences form the
basis of many rapid imaging scans such as breath-hold studies and MRA. The signal is refocussed
using a rephasing gradient.
How does TR and TE affect image weighting in GE imaging?
Like spin echo imaging the basic rules for TR and TE still apply. That being short TR and TE for T1
weighting and Long TR and TE for T2 weighting, however the actual values of TR and TE drop
considerably in GRE imaging due to the fact that we use a variable flip angle no longer the 90
degrees that is used in SE imaging.
What are some disadvantages of GE sequences?
With no 180 degree pulse, unfortunately GRE sequences are very sensitive to magnetic field
inhomogeneities. This may result in unwanted susceptibility artefacts at eg. tissue-air interfaces.
1|Page
,Due to the lack of a 180 degree refocusing pulse T2 contrast in GRE imaging is referred to as T2*
contrast as dephasing due to inhomogeneity will affect the image contrast.
What are the key differences between SE and GRE imaging?
SPIN ECHO
▪ 90 excitation pulse transfers all available Mz into the transverse plane.
▪ 180 refocusing pulse gives largest possible signal▪ Therefore high SNR and reduced
inhomogeneity artefact
▪ Long scan time
GRADIENT ECHO
▪ Utilises a gradient reversal to rephase spins
▪ Reduced flip angle therefore less signal in Mxy plane
▪ No 180 refocusing therefore susceptibility artefacts
▪ Lower SNR
▪ Shorter scan time
To achieve T1 weighting in a GRE sequence, what parameters should be set?
• T1 Weighting in GRE
Large Flip angle 70-110 degrees
Short TE 5-10ms
Short TR < 50ms
To achieve T2 weighting in a GRE sequence, what parameters should be set?
T2* Weighting in GRE
Small flip angle 5-20 degrees
Long TE 15-25ms
Short TR minimum possible depending on number of slices as the small flip angle ensures rapid
T1 recovery
To achieve PD weighting in a GRE sequence, what parameters should be set?
2|Page
,PD Weighting in GRE Small flip angle 5-20 degrees Short TE 5-10ms Short TR minimum possible
depending on number of slices as the small flip angle ensures rapid T1 recovery
What is steady state?
This is the condition that applies when the TR used is shorter than the T1 and the T2 of the
tissue. There will not be enough time for the transverse magnetisation to have decayed away
before the next RF pulse is applied. Each RF pulse produces a FID, each pair of pulses produces a
Hahn echo, and stimulated echoes arise from each set of three or more pulses. If the TR is short
enough, the tails of the FID's and the spin echoes merge to produce a continuous signal of
varying amplitude. The signal contains both FID and spin-echo components, with the TR being
equal to the TAU of the spin-echo
Explain how the residual transverse magnetisation is can be removed in a steady state
sequence?
The use of short TR intervals creates the steady state condition, but with these sequences the
residual transverse magnetisation is deliberately removed or 'spoiled' before the next excitation
pulse. Spoiling is done by;
• Gradient spoiling, where a gradient of varying amplitude is turned on just before the next RF
pulse. (Siemens' Flash)
• RF spoiling, where the phase of the RF is changed with each excitation and the receiver locks
on only to the phase of the preceding pulse. (GE's SPGR
What are gradient echo incoherent/spoiled gradient echo sequences usually used to for in
terms of weighting
These sequences are used to produce rapid T1 weighted images. eg. breath-hold liver studies.
Only the FID is re-phased - the spin-echo is spoiled and not sampled.
For GRE incoherent T1 weighted scans the following parameters are suggested
3|Page
, •Flip angle 30-45 degree
•Short TE : minimum possible: often two are used for in and out of phase (minimum TE ensures
minimal T2*) •Short TR : 20-50ms
How is a coherent gradient echo sequence acheived?
Short TR values ensure that the steady state is achieved with these sequences. The transverse
magnetisation left over at the time of the next excitation pulse is kept coherent using a re-
winder gradient after readout. This compensates for the dephasing which occurs due to the
phase encoding process.
What are coherent gradient echo sequences used to determine?
Coherent gradient echo pulse sequences produce images that are T2* weighted. They can be
used to determine if a vessel is patent or if a region contains fluid.
For GRE coherent T2* weighted scans the following parameters are suggested
For GRE coherent T2* weighted scans the following parameters are suggested
•Flip angle 30-45 degree
•Long TE: 15ms+ (this maximises T2* contrast)
•Short TR : 20-50ms
What is an EPI sequence and what do they achieve?
With echo planar imaging, a single echo train is used to collect data from all lines of K-space
during on TR period. Use of this technique subsequently considerably shortens the acquisition
time. There are two types of EPI sequences; SE and GRE sequences. All the lines of K-space can
be acquired in a single TR (in single shot EPI) or in two or more TR's. (in multishot EPI) The phase
and frequency encoding gradients are turned on and off very rapidly, a technique which allows
the rapid filling of K-space. EPI imaging is the sequence of choice for diffusion weighted imaging,
for which a EPI SE sequence is typically used. EPI imaging is more vulnerable to magnetic
susceptibility effects and provides greater tissue contrast than does imaging with standard GRE
sequences. EPI imaging sequences are widely used to assess cerebral perfusion.
4|Page
