MRI Registry Review-Data Acquisition and Processing

A short T1 inversion recovery (STIR) sequence can suppress the signal from: a)Fat b)Water c)A gadolinium enhancing lesion d)a and c

d)a and c

Reducing the TR: a)Decreases the signal-to-noise ratio (SNR) of the image b)Reduces the contrast based on T2 relaxation times of the tissues c)Increases saturation effects d)a and c

d)a and c

The following is (are) important in MRA sequences to minimize the loss of signal due to dephasing within a voxel: a)Long TR b)Small voxels c)Short TE d)b and c

d)b and c

In a spin echo sequence, the time between the 90° pulse and the 180° pulse is: a)TE b)TR c)T1 d)½ TE

d)½ TE

If a given conventional spin echo pulse sequence takes 12 minutes to acquire, a fast spin echo sequence using an ETL of six, with all other factors that affect scan time remaining the same, will take: a)2 minutes b)1 minute c)6 minutes d)4 minutes

a)2 minutes

In a 3D acquisition, the slices are produced by: a)A phase encoding gradient applied in the slice selection direction b)Multiple 180° pulses along the slice selection direction c)Sampling multiple lines of K space per pulse sequence repetition d)Very accurate RF pulses

a)A phase encoding gradient applied in the slice selection direction

Reducing NSA will reduce the scan time and: a)Decrease the SNR b)Increase the SNR by a factor of 1.41 c)Not affect the SNR d)Double the SNR

a)Decrease the SNR

Using a conventional spin echo multislice sequence, the number of slices allowed when increasing the TE from 20 ms to 40 ms: a)Decreases b)Is not affected c)Increases by a factor of TR × TE d)Doubles

a)Decreases

A major advantage of a 2D time of flight sequence over a 3D time of flight is the ability to: a)Image a larger area without saturation of the flowing blood b)Determine the percentage stenosis in the presence of a lesion c)Better image reverse flow d)Image a clot without showing the slower flow around it

a)Image a larger area without saturation of the flowing blood

The effective TE in a fast spin echo pulse sequence determines the: a)Image contrast b)Scan time c)Spatial resolution d)Number of frequency samples

a)Image contrast

In a vessel with a plaque producing a high degree of stenosis, the velocity of the blood flow in the center point of the stenosis is: a)Increased b)Decreased c)Reversed d)Unaffected

a)Increased

Increasing the TE: a)Increases the contrast based on T2 relaxation times of the tissues b)Reduces the contrast based on T2 relaxation times of the tissues c)Reduces the contrast based on T1 relaxation times of the tissues d)a and c

a)Increases the contrast based on T2 relaxation times of the tissues

The time during which the frequency encoding gradient is on: a)Increases with a reduction in receiver bandwidth b)Decreases with a reduction in receiver bandwidth c)Is not affected by a reduction in receiver bandwidth d)Cannot be changed by a reduction in receiver bandwidth

a)Increases with a reduction in receiver bandwidth

Creating additional images in various planes from a 3D dataset is accomplished by a technique known as: a)Multiplanar reconstruction b)Region of interest calculation c)Maximum intensity pixel d)Summation pixel projection

a)Multiplanar reconstruction

The presaturation pulses usually occur: a)Prior to the excitation pulse b)After the 180° pulse c)Between the 90° and 180° pulses d)Prior to the TE

a)Prior to the excitation pulse

If the TR of a gradient echo pulse sequence is considerably less than the T2 (and T2*), the condition that will exist is known as: a)Steady state b)Spin dephasing c)Spin rephasing d)Spin cancellation

a)Steady state

A chemical or spectral fat suppression sequence will suppress the signal from fat based on: a)The precessional frequency of fat b)The amount of fat in the target slice c)The T2 relaxation time of fat d)a and c

a)The precessional frequency of fat

Phase contrast techniques produce images in which the signal intensity within the vessel is dependent on (among other parameters) the: a)Velocity of the flowing blood b)T1 of the tissue c)FOV selected d)Number of phase encoding views

a)Velocity of the flowing blood

Cine studies are often performed on various joints. The main purpose of such a study is to: a)Visualize motion and function b)Visualize blood flow c)Measure muscle strength d)Impress referring physicians

a)Visualize motion and function

The SNR will increase in a 3D sequence with an increase in: a)FOV b)Number of slices c)TE d)a and b

d)a and b

An inversion recovery spin echo sequence begins with a: a)90° RF pulse b)180° RF pulse c)45° RF pulse d)a or b

b)180° RF pulse

If a phase resolution of 256 is desired, then the TR must be repeated (for 1 NSA): a)192 times b)256 times c)512 times d)Twice

b)256 times

To rephase the signal from moving spins, gradient moment nulling techniques use: a)An RF pulse b)A gradient c)A series of short rapid pulses strategically timed d)A flow encoding gradient

b)A gradient

Increasing the number of phase encodings will produce an image with: a)Increased voxel volume b)Decreased voxel volume c)An unchanged voxel volume d)Higher SNR

b)Decreased voxel volume

Increasing the matrix in the frequency direction from 256 to 512 will: a)Reduce the scan time b)Have no effect on the scan time c)Increase the scan time by a factor of 256/512 d)Double the scan time

b)Have no effect on the scan time

A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as: a)Non-phasic b)Incoherent c)Non-residual d)Magnetization prepared

b)Incoherent

Doubling the number of signals averaged (NSA) will: a)Decrease the SNR b)Increase the SNR c)Double the SNR d)Not affect the SNR

b)Increase the SNR

Using a 3D acquisition, the number of slices allowed when increasing the TR: a)Decreases b)Is not affected c)Increases by a factor of TR/2 d)Doubles

b)Is not affected

A major advantage of MRA over conventional angiography is that: a)Images with both heavy T1 and T2 weighting can be produced b)Multiple views can be produced from a single acquisition c)Much smaller catheters are used d)Less ionizing radiation is used

b)Multiple views can be produced from a single acquisition

Phase encoding is performed: a)After frequency encoding b)Prior to frequency encoding c)In place of frequency encoding d)During frequency encoding

b)Prior to frequency encoding

Presaturation pulses are often used to: a)Improve spatial resolution b)Reduce flow artifacts c)Reduce scan time d)Turn flowing blood bright

b)Reduce flow artifacts

The removal of signal from vessels in an MRA sequence is achieved by: a)Gradient moment nulling b)Spatial presaturation c)Spectral presaturation d)a and b

b)Spatial presaturation

If a STIR sequence using a TR of 3000, a TE of 20, and a T1 of 140 produces an image with dark fat and bright water. The contrast in such an image is primarily based on: a)Flow b)T1 c)T2 d)Dephasing

b)T1

In a phase contrast technique, it is possible to use the data to determine: a)The exact size of the vessel lumen b)The direction of blood flow c)The temporal displacement of the vessel d)The percentage stenosis of a lesion

b)The direction of blood flow

To produce the echo, a gradient echo pulse sequence uses: a)A gradient magnetic field only b)An RF pulse only c)A combination of a and b d)A switching device e)A combination of any two RF pulses

c)A combination of a and b

Cardiac cine acquisitions typically utilize: a)An inversion recovery pulse sequence b)A spin echo pulse sequence c)A gradient echo pulse sequence d)A fast spin echo pulse sequence

c)A gradient echo pulse sequence

Blood flow velocities are greater: a)Further away from the heart b)At a vessel wall c)At the center of a vessel d)In a 3D time of flight sequence

c)At the center of a vessel

The gradient that is on during the production of the echo is the: a)Phase b)Slice selection c)Frequency d)Oblique

c)Frequency

2D acquisitions generally require between slices: a)Wait time b)Gradient refocusing c)Gaps d)An inversion pulse

c)Gaps

Acquiring half of the phase views of K space and then interpolating the data for the other half is a technique known as: a)Zero fill b)Fast spin echo c)Half Fourier d)Power scanning

c)Half Fourier

Using a conventional spin echo multislice sequence, the number of slices allowed when increasing the TR: a)Decreases b)Is not affected c)Increases by a factor of TR/TE d)Doubles

c)Increases by a factor of TR/TE

Decreasing the receiver bandwidth: a)Decreases the SNR b)Inverts the SNR c)Increases the SNR d)Has no effect on the SNR

c)Increases the SNR

Complete saturation is a condition where: a)Not enough time is given to allow the T2 decay to complete b)The image becomes brighter c)Longitudinal magnetization is not allowed to recover between excitations d)Proton density effects predominate

c)Longitudinal magnetization is not allowed to recover between excitations

To create a projection image in MRA, the technique most commonly employed is: a)Multiplanar reconstruction b)Region of interest calculation c)Maximum intensity pixel d)Summation pixel projection

c)Maximum intensity pixel

In choosing the direction of phase encoding, the technologist usually considers the direction in which: a)The most signal is needed b)The scan time will not be affected c)Motion artifacts traverse the least tissue or areas of interest d)The resolution will not be distorted

c)Motion artifacts traverse the least tissue or areas of interest

In a gradient echo sequence, reducing the flip angle while holding the TR constant reduces: a)T2* contrast weighting b)Spin density contrast weighting c)Saturation d)Scan time

c)Saturation

In a time of flight sequence, the tissue is hypointense relative to flowing blood because of: a)T2 effects b)T2* effects c)Saturation effects d)Inhomogeneities

c)Saturation effects

Gradient moment nulling is most effective when correcting for motion induced signal loss from: a)Pulsatile flow b)No flow c)Slow constant flow d)Magnetic field inhomogeneities

c)Slow constant flow

In a conventional spin echo multi-echo sequence, it is possible to create multiple images, each with different amounts of: a)T1 weighting b)Phase encoding c)T2 weighting d)Spatial resolution

c)T2 weighting

In an inversion recovery pulse sequence, the time between the initializing 180° pulse and the 90° pulse is known as: a)TE b)TR c)TI d)T1

c)TI

The time between excitation pulses is known as the: a)T1 b)TE c)TR d)PR

c)TR

With conventional spin echo each 'line' of K space is filled in each: a)Frequency encoding period b)TE period c)TR period d)Excitation period

c)TR period

In a fast spin echo sequence, the central lines of K space are associated with: a)The image's spatial resolution b)The TR c)The effective TE d)The scan time

c)The effective TE

In a fast spin echo sequence, the effective TE is the echo that is performed with: a)The outer views of K space b)The high amplitude phase encoding gradients c)The low amplitude phase encoding gradients d)The first phase encoding steps

c)The low amplitude phase encoding gradients

Gradient echo sequences use flip angles: a)Less than 90° b)That vary between pulse repetitions c)To control saturation effects d)To reduce SAR for larger patients

c)To control saturation effects

A major advantage of 3D time of flight techniques over 2D time of flight is the ability to: a)Determine blood flow velocities b)Shorten imaging time c)Visualize smaller vessels d)Reduce the signal intensity from stationary tissue

c)Visualize smaller vessels

Doubling the NSA will increase the SNR by a factor of: a)2 b)4 c)1.6 d)1.41

d)1.41

The MRA sequence that is more sensitive to slow flow is: a)3D inversion prepared b)3D time of flight c)Multislice vascular d)2D time of flight

d)2D time of flight

Reducing the FOV by a factor of 2 will reduce the voxel volume by a factor of: a)√2 b)2 c)8 d)4

d)4

With a fast spin echo sequence utilizing an eight echo train length (ETL), the number of lines of K space filled during each TR will be: a)4 b)2 c)12 d)8

d)8

The 180° pulse that follows the initial 90° pulse in a spin echo sequence will cause the NMR signal to reappear while correcting for: a)Slight magnetic field inhomogeneities b)Chemical shift c)Slight magnetic susceptibility effects d)All of the above

d)All of the above

The top portion of K space is a mirror image of the: a)Right b)Left c)Top d)Bottom

d)Bottom

Using a 3D acquisition, increasing the number of slices from 64 to 128: a)Reduces the scan time b)Has no effect on the scan time c)Increases the scan time by a factor of 1.41 d)Doubles the scan time

d)Doubles the scan time

In a time of flight sequence, flowing blood is hyperintense relative to stationary tissue because of: a)T2 effects b)The coil being used c)The saturation pulse used d)Flow related enhancement

d)Flow related enhancement

One direction in K space represents phase, while the other represents: a)Position b)Intensity c)Contrast d)Frequency

d)Frequency

Each 'frame' of a cardiac cine sequence displays the heart: a)In various imaging planes b)With varying degrees of spatial resolution c)From a slightly different viewpoint d)In different phases of the cardiac cycle

d)In different phases of the cardiac cycle

Reducing the TE: a)Increases the contrast based on T1 relaxation times b)Increases the spin density contrast weighting c)Reduces saturation effects d)Reduces contrast based on T2 relaxation times

d)Reduces contrast based on T2 relaxation times

The scan time for a 3D acquisition is given by: a)TR × NSA × bandwidth × slice thickness b)TR × NSA × number of phase encodings × number of slabs c)TR × NSA × number of phase encodings × echo train length d)TR × NSA × number of phase encodings × number of slices

d)TR × NSA × number of phase encodings × number of slices

In an inversion recovery pulse sequence, image contrast is controlled by: a)TR and TE only b)TI only c)TI and TE only d)TR, TE, and T1

d)TR, TE, and T1

Another name for TI is: a)Alpha b)Theta c)Sigma d)Tau

d)Tau

When triggering a scan from the patient's ECG, the TR of sequence is determined by: a)The number of phase encodings selected b)The number of phases of the heart cycle being imaged c)The number of frequency encodings selected d)The patient's heart rate

d)The patient's heart rate

Single order gradient moment nulling does not compensate for: a)Accelerated flow b)Reverse flow c)Constant velocity flow d)a and b

d)a and b

In a spin echo sequence, flowing blood is normally seen as a signal void because: a)The TE is too long to image flow b)Repetition times used in spin echo sequences are too long to image flow c)The 90° pulse and the 180° pulse are both slice selective d)The flip angle is always 90° e)a and c

e)a and c