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