The scan time for a 3D acquisition is given by:
TR X NEX X phase encodings X number of slices
TR X NEX X phase encodings X slice thickness
(TR X NEX X phase encodings)/echo train length
TR X NEX X phase encodings
The scan time for a 2D acquisition is determined by:
TR X NEX X phase encodings X FOV
During a conventional spin echo exam, one line of k-space is filled each
frequency encoding period
TE period
TR period
TI period
Noise represents
current induced in the phase encoding gradient
frequencies that exist randomly in space and time
frequencies that exist in a structured environment at a specific location
Un-captured voltage potential
Changing the size of a voxel in the frequency direction will
have no effect on the scan time
double the scan time
increase the scan time by a factor of 0.5
What is the slice thickness for an isotropic voxel with a 20 cm field of view and a 256 X 256 matrix
13 cm
0.8 mm
3 cm
1.3 mm
Where in a spin echo pulse sequence are pre-saturation pulses usually placed?
after the excitation pulse
after the 180 degree RF pulse
between the 90 degree and 180 degree RF pulse
prior to the excitation pulse
Which of the following TR parameters will provide the highest signal to noise?
1800 ms
400 ms
2500 ms
800 ms
Which of the following TE parameters will provide the highest signal to noise?
120 ms
20 ms
40 ms
80 ms
Which of the following flip angles will provide the highest signal to noise?
45 degrees
115 degrees
90 degrees
5 degrees
