Image Basics/ Image formation Solved 100%
Correct- MRI
T1 relaxation is also called - ANS-spin lattice
T1 regrowth along which axis - ANS-longitudinal (z)
what is the percent of recovery for T1 relaxation time - ANS-63% longitudinal
magnetization
T2 relaxation take what type of percent - ANS-37
Describe FAT time as it relates to T1 & T2 relaxation times - ANS-short
short
Describe water as it relates to T1 & T2 relaxation times - ANS-Long
Long
To obtain low signal, there must be _________________ component of
magnetization in the transverse plane of the coil - ANS-a small
To obtain high signal there has to be a _____________ component of
magnetization in the transverse plane of the coil - ANS-large
In a T1 weighted image explain the difference between Fat and water
and what that means in relation ship to the NMV - ANS-T1 time fat is shorter than
water
Fat Bright- high signal
Water- dark -low signal
NMV in fat realigns with Bo faster than water
In a T2 weighted image explain the difference between Fat and water
and what that means in relation ship to the NMV - ANS-T2 time fat is shorter than
water-- but the magnitude of fat is to small
fat- dark
water- bright
what is the controlling parameter of T1 images - ANS-TR
, what is the controlling parameter of T2 weighted images - ANS-TE
Name 4 things that increasing TR will do - ANS-improve SNR
Increase Scan Time
Reduce T1
Increase availabile number of slices
name what Increasing TE will do - ANS-Lower SNR
do you have better SNR with short or long TE - ANS-better overall signal with the
shortest TE
What are the TR and TE parameters for T1 weighted images - ANS-TR=350-700 ms
TE=10-30 ms
What are the TR and TE parameters for T2 weighted images - ANS-TR= 3000-6000
TE= 70-120ms
What are the TR and TE parameters for PD weighted images - ANS-TR 1500-3000
TE- 10-30
if TR is doubled what happens to the scan time - ANS-doubled
what is the formula to calculate scan time
2D vs 3D vs Fast spin Echos - ANS-TR x phase matrix x nex. - 2D
TR x phase matrix x NEX X number of slabs -3D
Fast spin echos: TR x Phase matrix x (NEX/ETL)
what are some ways you can reduce scan time (3) - ANS-reduce TR
reduce NEX increase parallel imaging factors
Changing slice thickness directs affects (3) - ANS-signal to noise ratio of the image
image resolution
anatomical coverage
when you increase your NEX/NSA SNR increase by - ANS-by the square root (√) of
the % increase.
does NEX have an effect on pixel size - ANS-no
when you make your matrix smaller what happens to the size of the pixels
SNR
Correct- MRI
T1 relaxation is also called - ANS-spin lattice
T1 regrowth along which axis - ANS-longitudinal (z)
what is the percent of recovery for T1 relaxation time - ANS-63% longitudinal
magnetization
T2 relaxation take what type of percent - ANS-37
Describe FAT time as it relates to T1 & T2 relaxation times - ANS-short
short
Describe water as it relates to T1 & T2 relaxation times - ANS-Long
Long
To obtain low signal, there must be _________________ component of
magnetization in the transverse plane of the coil - ANS-a small
To obtain high signal there has to be a _____________ component of
magnetization in the transverse plane of the coil - ANS-large
In a T1 weighted image explain the difference between Fat and water
and what that means in relation ship to the NMV - ANS-T1 time fat is shorter than
water
Fat Bright- high signal
Water- dark -low signal
NMV in fat realigns with Bo faster than water
In a T2 weighted image explain the difference between Fat and water
and what that means in relation ship to the NMV - ANS-T2 time fat is shorter than
water-- but the magnitude of fat is to small
fat- dark
water- bright
what is the controlling parameter of T1 images - ANS-TR
, what is the controlling parameter of T2 weighted images - ANS-TE
Name 4 things that increasing TR will do - ANS-improve SNR
Increase Scan Time
Reduce T1
Increase availabile number of slices
name what Increasing TE will do - ANS-Lower SNR
do you have better SNR with short or long TE - ANS-better overall signal with the
shortest TE
What are the TR and TE parameters for T1 weighted images - ANS-TR=350-700 ms
TE=10-30 ms
What are the TR and TE parameters for T2 weighted images - ANS-TR= 3000-6000
TE= 70-120ms
What are the TR and TE parameters for PD weighted images - ANS-TR 1500-3000
TE- 10-30
if TR is doubled what happens to the scan time - ANS-doubled
what is the formula to calculate scan time
2D vs 3D vs Fast spin Echos - ANS-TR x phase matrix x nex. - 2D
TR x phase matrix x NEX X number of slabs -3D
Fast spin echos: TR x Phase matrix x (NEX/ETL)
what are some ways you can reduce scan time (3) - ANS-reduce TR
reduce NEX increase parallel imaging factors
Changing slice thickness directs affects (3) - ANS-signal to noise ratio of the image
image resolution
anatomical coverage
when you increase your NEX/NSA SNR increase by - ANS-by the square root (√) of
the % increase.
does NEX have an effect on pixel size - ANS-no
when you make your matrix smaller what happens to the size of the pixels
SNR
