AMRI310 WK8 - k-space, FOV, pixel,
voxel, computer systems
k-space is defined as
the storage location of MR signal data
k-space and how image contrast is managed
why is data on the top half symmetrical to the data on the bottom half?
why do we use conjugate symmetry?
scan time reduces!
k-space filling
study this!
collecting the low frequency(high amplitude signal) data points in k-space at
the start of the scan(in a spiral fashion) is also known as _____ k-space filling
centric k-space filling
,centric k-space filling
what gradient determines FOV
FEG
steep gradient = small FOV
FOV (matrix)
256x512
first number is Ny(phase)
second number is Nx(frequency)
how to find the pixel size(math)
FOV/matrix = pixel size
if FOV is in cm, you must convert it to
millimeters by multiplying x 10
example: 18cm = 180mm
10cm = __mm
, 100
calculate: FOV 220mm and matrix of 256
0.86mm
divide 220/256=0.86
pixel area is calculated by multiplying the what by what?
phase dimension x frequency dimension
0.75mm phase direction pixel; 0.75mm frequency direction pixel =
0.5625mm^2 pixel size(0.75x0.75)
voxel size
voxel defined as volume element; 3D
calculate voxel volume or pixel area
FOV/Matrix =
pixel size
voxel, computer systems
k-space is defined as
the storage location of MR signal data
k-space and how image contrast is managed
why is data on the top half symmetrical to the data on the bottom half?
why do we use conjugate symmetry?
scan time reduces!
k-space filling
study this!
collecting the low frequency(high amplitude signal) data points in k-space at
the start of the scan(in a spiral fashion) is also known as _____ k-space filling
centric k-space filling
,centric k-space filling
what gradient determines FOV
FEG
steep gradient = small FOV
FOV (matrix)
256x512
first number is Ny(phase)
second number is Nx(frequency)
how to find the pixel size(math)
FOV/matrix = pixel size
if FOV is in cm, you must convert it to
millimeters by multiplying x 10
example: 18cm = 180mm
10cm = __mm
, 100
calculate: FOV 220mm and matrix of 256
0.86mm
divide 220/256=0.86
pixel area is calculated by multiplying the what by what?
phase dimension x frequency dimension
0.75mm phase direction pixel; 0.75mm frequency direction pixel =
0.5625mm^2 pixel size(0.75x0.75)
voxel size
voxel defined as volume element; 3D
calculate voxel volume or pixel area
FOV/Matrix =
pixel size
