MR001 Test 8 Study Guide
Small FA in GRE - Answer 5-20 degrees
SE long TE - Answer 60+ ms
GRE short TR - Answer <50 ms
Medium FA in GRE - Answer 30-45 degrees
Large FA in GRE - Answer 70+ degrees
GRE long TE - Answer 15-25 ms
SE long TR - Answer 2000+ ms
SE short TR - Answer 300-700 ms
GRE long TR - Answer 100+ ms
SE short TE - Answer 10-25 ms
GRE short TE - Answer 1-5 ms
Spin Echo (SE) pulse sequence - Answer 90 degree RF excitation pulse, followed by 180
degree rephasing pulse. This produces a spin echo.
Can use two 180 degree rephasing pulses to record two echos, thus getting 2 scans at
once (PDW and T2W)
Gradient Echo (GRE) pulse sequence - Answer An alpha pulse of anything less than 90
degrees (a variable flip angle), followed by use of gradients to dephase and rephase the
FID
This produces a gradient echo.
What weights do we use GRE for? - Answer T1W, T2*W, PDW
What weights do we use SE for? - Answer T1W, T2W, PDW
Spoiler gradient - Answer Gradient that dephases the nuclei
Rewinder gradient - Answer Gradient that rephases and creates a coherent gradient
echo
Cons of GRE - Answer -No 180 Degree pulse to compensate for mag field inhomogeneity
-No true T2W, only T2*W (due to inhomogeneity not being eliminated)
-Can only be run on stronger field scanners
Small FA in GRE - Answer 5-20 degrees
SE long TE - Answer 60+ ms
GRE short TR - Answer <50 ms
Medium FA in GRE - Answer 30-45 degrees
Large FA in GRE - Answer 70+ degrees
GRE long TE - Answer 15-25 ms
SE long TR - Answer 2000+ ms
SE short TR - Answer 300-700 ms
GRE long TR - Answer 100+ ms
SE short TE - Answer 10-25 ms
GRE short TE - Answer 1-5 ms
Spin Echo (SE) pulse sequence - Answer 90 degree RF excitation pulse, followed by 180
degree rephasing pulse. This produces a spin echo.
Can use two 180 degree rephasing pulses to record two echos, thus getting 2 scans at
once (PDW and T2W)
Gradient Echo (GRE) pulse sequence - Answer An alpha pulse of anything less than 90
degrees (a variable flip angle), followed by use of gradients to dephase and rephase the
FID
This produces a gradient echo.
What weights do we use GRE for? - Answer T1W, T2*W, PDW
What weights do we use SE for? - Answer T1W, T2W, PDW
Spoiler gradient - Answer Gradient that dephases the nuclei
Rewinder gradient - Answer Gradient that rephases and creates a coherent gradient
echo
Cons of GRE - Answer -No 180 Degree pulse to compensate for mag field inhomogeneity
-No true T2W, only T2*W (due to inhomogeneity not being eliminated)
-Can only be run on stronger field scanners
