MRI Exam Three Quiz Questions
in conventional spin echo pulse sequence, how many phase encoding steps are achieved per TR?
1
which of the following echo times provides the best SNR assuming all other parameters remain constant?
15 ms
Place the following rephasing events in order 1. spin echo produced 2. 90 degree RF pulse 3. flipping of trailing edge and leading edge 4. 180 degree RF pulse
2,4,3,1
Place the following spin echo sequence events in the correct order 1. signal measurement 2. 180 degree RF pulse 3. 90 degree RF pulse
3,2,1
which of the following is a method of eliminating residual transverse magnetization? RF spoiling gradient rewinding gradient spoiling
A and C
with the parameters given, which protocol gives the highest signal to noise ratio?
Long TR; Short TE; Low Matrix
what effect will increasing the echo time have on SNR?
SNR will decrease
the inversion recovery pulse sequences that is used to suppress fat in a T1 weighted image is known as _____
STIR
Ability to distinguish one structure from another on an image is known as
Spatial resolution
Effective TE is defined as
TE selected to accurately weigh an image during a TSE pulse sequence
in an inversion recovery pulse sequence, what is the term for the time between the initial 180 degree RF pulses and the 90 degree RF pulse?
TI
what is the time interval between the 90 degree RF pulse and a subsequent 90 degree RF pulse applied to the same slice?
TR
Tau is measured as
Time between 90 degree excitation pulse and 180 degree rephasing pulse time form 90 degree excitation pulse to the next 90 degree excitation pulse
changing the TR will directly affect which of the following?
acquisition time
when gradients are applied to rephase the hydrogen nuclei, the gradients are applied
across the entire gradient length
In the steady state incoherent pulse sequence the use of a "spoiler/crusher" pulse is to
aid in the dephasing process of the residual magnetization
Gradient spoiling uses which of the following gradients to eliminate leftover transverse magnetization? Frequency encoding slice select phase encoding
all of the above
which of the following is a parameter that directly affects signal to noise ratio? Voxel Repetition time number of excitations
all of the above
which of the following is an advantage of gradient echo pulse sequences? increased sensitivity to flow volume acquisition possible decreased scan time
all of the above
which parameter(s) effect total scan times? repetition time number of phase encoding steps number of excitations
all of the above
at what location within the kspace file is the signal information placed from the effective TE of a FSE pulse sequence
central lines
gradient echo pulse sequences that preserve left over transverse magnetization are said to be ____
coherent
which pulse sequence results in filling all the lines of k-space in a single TR period?
echo planar imaging
for an inversion recovery pulse sequences, the echo time is measured from the
excitation pulse to the middle of the spin echo
Which is true of a conventional spin echo pulse sequence where two echoes are produced?
first echo is PD weighted and the second echo is T2 weighted
In gradient echo pulse sequence (not including steady state), which is used to dephase and rephase nuclei?
frequency encoding
When image matrix is increased, spatial resolution _____
increases
when TR is increased, acquisition time ______
increases
when repetition time is increased, signal to nose ratio _____
increases
The type of spin echo pulse sequence that begins with 180 degree inversion RF pulse and is followed by a 90 degree excitation pulse in known as ____
inversion recovery
which pulse sequences will best minimize the influence from CSF (cerebral spinal fluid)?
inversion recovery with a long TI time
In a gradient echo planar pulse sequence, using a short effective TE produces what type of weighting?
proton density weighting
STIR is a pulse sequence designed to _____ the signal generated from fat
reduce
which pulse sequence result in filling all lines of kspace in a single TR period?
single shot turbo spin echo
The depth of a volume element is determined by what parameter
slice thickness
Which type of magnetic moments create the trailing edge during dephasing
slow magnetic moments
in a gradient echo pulse sequences, the process eliminating residual transverse magnetization is known as ____
spoiling
The echoes generated farther from the effective TE of a TSE pulse sequence will result from a _____ phasing encoding gradient
steep
Inversion recovery pulse sequences can be used in conjunction with fast spin echo sequences True or Flase
true
Which of the following ins likely for a T1 weighted fast spin echo sequences
turbo factor of 4