imaging Flashcards
assuming all other parameters are the same an echo time of ____ ms provides the vest signal to noise ration
15
in a fast spin echo sequence with a 28 cm FOV 256x512 matric tr 2200 te 90 5 mm slice thickness ETL8 NEX 3 what will the scan time be
3 min 31 sec
tr x phase matric x nex / etl
then divide by 1000
with regards to kspace the data containing high resolution are located along
the outer lines
with regards to kspace the data containing signal and contrast info are located
the central lines
the scan time of a fast spine echo sequence utilizing TR 3500ms TE 90ms 256x256 NSA1 220mm FOV and ETL 5
3 min
TR x Phase matrix x NSA / ETL
then divide by 1000
assuming all other parameters are the same a ____ ms TR provides the best SNR
800
choose the correct slice thickness to create an isotropic voxel for the following TR 2000 TE 90 matric 256x256 FOV 32cm
1.25
FOV/matrix
each line of k space is defined by the
phase encoding gradient
high amplitude signals are stored in the
center portion of kspace
a reduction in fov will result in
decrease in SNR
the central lines of kspace are associated with ____ in a fast spin echo sequence
contrast information
a method of reducing mri scan time by not filling as many line of kspace in the phase direction while maintaining spatial resolution is known as
rectangular FOV
reducing the number of lines filled in kspace will produce an image
with decrease in spatial resolution
if the NEX is increased for 2 to 6 the singal to noise ratio increase would be
1.7
calculate the voxel volume for the following pulse sequence TR 2000 TE 85 FOV 28cm matrix 272x 320 5 mm slice thickness 3 NSA
4.55mm3
pixel area x slice thickness=voxel volume
.91mm2 x 5 = 4.55 mm3
