Review Questions for MRI Part C

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1.41

Doubling the NSA will reduce the SNR by a factor of

And increase the SNR by the square root of 2

Doubling the number of signals averaged (NSA) will

Subtraction

During contrast enhanced imaging of the abdominal organs, images are acquired without and with gadolinium (Gd) enhancement. To better visualize contrast enhancement, _________ can be performed

Centric

During dynamic enhanced imaging for vasculature or visceral structures, contrast it administered and K-space is filled with ___________ to ensure that the contrast enhancement is well visualized

Incoherent Gradient echoes

Dynamic enhanced MRA sequences of the renal arteries are performed with the use of

And different phases of the cardiac cycle

Each "frame" of a cardiac Ciné sequence displays the heart

The Ernst angle

For a given tissue with a given T1 relaxation time and TR, the flip angle, which will result in the maximum signal for the tissue, is

1/2 TE

In a spin echo sequence, the time between the 90° RF pulse and the 180° RF pulse is known as the:

Flow-related enhancement

In a time of flight sequence, flowing blood is HYPERintense relative to stationary tissue because of the

saturation effect

In a time of flight sequence, the tissue is HYPOintense relative to flowing blood because of the

Increased

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

TR x NSA x number of phase encodings x number of slices

In a volume acquisition, the scan time is

D. normal myocardium

In an image acquired with a balance GRE sequence (figure C.2), all of the following have high (bright) signal EXCEPT A. blood in the left ventricle B. CSF C. IVC D. Normal myocardium

TI

In an inversion recovery Pulse sequence, the time between the initializing 180° pulse in the 90° pulse is known as

TR, TE, and TI

In an inversion recovery pulse sequence, image contrast is controlled by

Motion, artifacts, transverse, the least tissue or area of interest

In choosing the direction of phase encoding, the technologist usually considers the direction in which the

Acquisition Vauxhall should be isotropic

In order to produce high-quality reformatted images, the

Reference or calibration scan

In order to reconstruct an image acquired using parallel imaging, which of the following may be required

20

In the multi Echo spin Echo sequence shown in figure C.1, the number of long TE images created with a 20 slice sequence will be

40

In the multi Echo spin echo sequence shown in figure C.1, the total number of images created with a 20 slice sequence will be

20

In the multi-echo spin Echo sequence shown in figure C.1, the number of short TE images created with a 20 slicing sequence will be

T2 information

In the multi-echo spin echo sequence shown in figure C .1, images will be acquired with varying amounts of

2

In the multi-echo spin echo sequence shown in figure C.1, the number of images per slice location created will be

Multi shot 4-shot SE-EPI, 256 phase x 256 frequency

In which of the following EPI sequences would one expect there to be the least susceptibility (distortion) artifacts

T2 FLAIR

In which of the following sequences would MS plaques appear hyperintense relative to both CSF and normal white matter

Does not affect scan time

Increasing FOV

Does not affect scan time

Increasing TE

Increases scan time

Increasing TR

Increases scan time

Increasing the NSA

A. Increases the contrast based on T2 relaxation times of the tissues

Increasing the TE A. Increases the contrast based on T2 relaxation times of the tissues B. Reduces the contrast base on T2 relaxation times of the tissues C. Reduces the contrast based on T1 relaxation times of the tissues D. A and C

More T2 information

Increasing the TE yields images with

Less T1 information

Increasing the TR yields images with

Increases SNR up to the Ernst angle

Increasing the flip angle

Morty T1 information

Increasing the flip angle yields images with

Decreases SNR

Increasing the matrix

Have no effect on a scan time

Increasing the matrix in the frequency direction from 256 to 512 will

Increases

Increasing the number of phase encoding (matrix) from 128 to 256 by a factor of two, the SNR

Decrease voxel volume

Increasing the number of phasing encoding will produce an image with

Does not affect Scan time

Increasing the number of slices in a 2D acquisition

Increases scan time

Increasing the phase matrix

Has no effect on the available ETL

Increasing the receiver bandwidth (wide BW):

Does not affect scan time

Increasing the slice thickness

Increases SNR

Increasing the slice thickness

Laminar flow

Normal blood flow (demonstrated by a parabolic blood flow profile) is known as

Turbulent flow

Normal blood flow was known as

Frequency

One Direction in K-space represents phase, while the other represents

SAT

Parallel imaging techniques are also known as all of the following EXCEPT A. SENSE B. SMASH C. GRAPPA D. SAT

Velocity of flowing blood

Phase contrast techniques produce images in which the signal intensity within the vessel is dependent on (among other parameters) the

Prior to frequency encoding

Phase encoding is performed

Maximum intensity pixel

To create a projection image an MRA, the technique most commonly employed is

Collapse image

To evaluate the circle of Willis (COW), 3D TOF MRA sequences are acquired and displayed as an axial view of all of the vasculature. This image is known as

Segmenting

To evaluate the circle of Willis (COW), 3D TOF MRA sequences are required and back ground tissue is carved out to provide better visualization of the intercranial vasculature. This step is known as

Single-shot EPI acquisition

To keep scan time at a minimal, diffusion imaging is typically performed with

Gradient

To rephase the signal from moving spins, gradient moment nulling techniques use a

Fourier transformation converts signal data from FID into spectrum

True

Gradient Echo sequences can yield either T1 or T2* characteristics

True

Double scan time

Using a 3D acquisition, increasing the number of slices from 64 to 128

It's not affected

Using a 3D acquisition, the number of slices allowed one increasing the TR

Decreases

Using a conventional spin Echo multi slice sequence, The number of slices allowed when increasing the TE from 20 to 40 MS

Increases by a factor of TR/TE

Using a conventional spin Echo multi slice sequence, the number of slices available when increasing the TR

A gradient echo pulse sequence

Cardiac Ciné acquisitions typically utilize

Myocardial tagging

Cardiac analysis performed with a technique using SAT band to assess wall motion is known as

Volume Rendering (VR)

A 3D data set can be reconstructed to display "what appears to be" a 3D image of the anatomy. This technique is known as

CSF

A FLAIR sequence is utilized to suppress the signal of

Processional frequency of fat

A chemical or spectral fat suppression sequence will suppress the signal from fat based on the

Incoherent/spoiled

A gradient Echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as

Visualize smaller vessels

A major advantage of 3D time of flight techniques over 2D time of flight is the ability to:

Multiple views can be produced from a single acquisition

A major advantage of MRA over conventional angiography is that

Image a larger area without saturation of the flowing blood

A major advantage of a 2D time of flight sequence over a 3D time of flight sequence is the ability to

#PEs = 256 and ETL = 64

A multi shot FSE sequence is a quired (with four shots) when

D. A and C

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

#PEs = 256 and ETL = 256

A single shot FSE sequence is acquired when

Alpha pulse that varies with desired image contrast

A typical gradient Echo sequence begins with a

180, 90, 180

A typical inversion recovery IR spin Echo sequence uses pulses

90, 180

A typical spin Echo SE sequence uses pulses

Half Fourier

Acquiring half of the phase views of K-space and then interpolating the data for the other half is a technique known as

C. Centric K space filling

All of the techniques below can be utilized to optimally time the start of a contrast enhanced MRA except A. Automated bolus direction B. Test bolus C. Centric K space filling D. Real time/fluoro triggering

180 RF pulse

An inversion recovery (IR) spin Echo sequence begins with a

TAU

Another name for TI is

Fourier transformation is performed in the

Array processor

SNR decreases

As TE increases

SNR increases up to a point

As the TR increases

Gaps

Between slices 2D acquisitions generally require

Accelerated flow

Blood flow at the area of stenosis (vascular narrowing) is known as

At the center of a vessel

Blood flow velocity our greatest

Amplitude, timing, and/or duration of the diffusion gradient

Changing the b-value alters the

Visualize motion and function

Ciné (kinematic) studies are often performed on various joints. The main purpose of such a study is two

Centric

Collecting the low frequency (high amplitude signal) data points in K-space at the start of the scan (in a rectilinear fashion) is known as

Elliptic centric

Collecting the low frequency (high amplitude signal) data points in k-space at the start of the scan (in a spiral fashion) is known as ________________________.

Longitudinal magnetization is not allowed to recover between excitations

Complete saturation is a condition where

multiplanar reformation

Creating additional images in various planes from a 3D data set is accomplished by a technique known as

Decreases the number of slices

Decreasing the receiver band with (narrow BW)

Increases SNR

Decreasing the receiver bandwidth (narrow BW)

Increases chemical shift artifact

Decreasing the receiver bandwidth (narrow BW)

Increases readout time

Decreasing the receiver bandwidth (narrow BW):

Increases susceptibility artifact

Decreasing the receiver bandwidth (narrow BW):

B. Incoherent Gradient echoes

Gradient Echo sequences acquired for high signal from fluid are known as all of the following except A. coherent gradient echoes B. Incoherent gradient echoes C. Steady state gradient Echoes D. T2*gradient echoes

D. Aliasing

Gradient Echo sequences can yield either T1 or T2* characteristics, with influences caused by all of the following except A. susceptibility B. Inhomogeneity C. Chemical shift D. Aliasing

Susceptibility

Gradient echo sequences acquired for the evaluation of hemorrhagic lesions rely on

To control saturation effects

Gradient echo sequences use flip angles:

Slow constant flow

Gradient moment nulling is most effective when correcting for motion-induced signal loss from:

Tissues or substances with extremely short T1 relaxation times

Having acquired a 3D TOF, when producing an MRA projection image set using the MIP technique, which of the following can appear bright and therefore the same as flow within a vessel

T1

If a STIR sequence using a TR of 3000, a TE of 20, and a TI of 140 produces an image with dark fat and bright water. The contrast in such an image is primarily based on

2 minutes

If a 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

256 times

If a phase Resolution of 256 is desired, then the TR must be repeated for (one in NSA)

69%

If one desires to know the signal from a specific tissue using an inversion recovery sequence, one should select an inversion time that is_______ of the T1 relaxation time of that tissue

2

If the pulse sequence shown in figure C.1 were a fast spin echo sequence, the number of lines of K space field during each TR period would be

Steady state

If they TR of a gradient echo pulse sequence is considerably less than the T2 (and T2*), the condition that will exist is known as

TR (time to repetition) X number of signals averaged (NSA) X number of phase encodings (#PEs)

In a 2D conventional spin Echo multislice pulse sequence, scan time is given by the equation

A phase encoding gradient applied in the slice selection direction

In a 3-D acquisition, the slices are produced by

Weighted for the ratio of T2/T1

In a balanced GRE acquisition, the contrast weighting is:

T2 weighting

In a conventional spin echo multi echo sequence, it is possible to create multiple images, each with different amounts of

Effective TE

In a fast and Echo sequence, the central lines of case space are associated with the

Longer ETL

In a fast spin Echo (FSE) sequence, acquired with long effective TE (T2 weighted images), scan time can be reduced by the selection of

Shorter ETL

In a fast spin Echo (FSE) sequence, acquired with short effective TE (T1 or PD weighted images), blurring can be reduced by the selection of

Low amplitude phase encoding gradients

In a fast spin Echo sequence, the effective TE is the echo that is performed with the

Four times as fast

In a fast spin echo pulse sequence, if the echo train length is increased by a factor of four, the scan time will be

High amplitude phase encoding Gradients

In a fast spin echo sequence, spatial resolution is associated with

Saturation

In a gradient Echo sequence, reducing the flip angle while holding the TR constant reduces

Direction of blood flow

In a phase contrast technique, it is possible to use the data to determine the

E. A and C

In a span Echo sequence, flowing blood is normally seen as a signal void because the A. TE is too long to image flow B. Repetition times used in span Echo sequences are too long to image flow C. 90° pulse and 180° pulse are both slice selective D. Flip angle is always 90° E. A and C

Reduce flow artifacts

Presaturation pulses are often used to:

Increases SNR

Reduces the TE

Decrease the SNR

Reducing NSA will reduce the scan time and

Increases scan time

Reducing the ETL

4

Reducing the FOV by a factor of 2 will reduce the Voxel volume by a factor of

Reduces contrast based on T2 relaxation times

Reducing the TE

Less T2 information

Reducing the TE yields images with

D. A and C

Reducing the TR down to or below the T1 relaxation time of the tissue 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 affects D. A and C

Morty T1 information

Reducing the TR yields images with

Less T1 information

Reducing the flip angle yields images with

D. Fluid (CSF)

STIR sequences can suppress the signal from all of the following except a. fat within bone marrow B. Gadolinium enhancing lesions C. Retro orbital fat D. Fluid (CSF)

D. Fluid (CSF)

Short tau inversion recovery (STIR) sequences are typically used for the evaluation of all of the following except A. Musculoskeletal contusion B. Fat suppression C. Lesions within the retro orbital fat D. Fluid CSF

D. A and B

Single order gradient moment nulling does not compensate for A. Accelerated flow B. Reverse flow C. Constant velocity flow D. A and B

Periventricular white matter disease

T2 weighted fluid attenuated inversion recovery (FLAIR) sequences are typically use for the evaluation of

Frequency

The "readout" gradient is also known as the

D. All of the above

The 180° pulse that follows the initial 90° pulse in a span 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

Edge detail (spatial resolution)

The High frequency (low amplitude) data points in K-space provide

3D phase contrast MRA (PC MRA)

The MRA sequence that can be made sensitive to any flow velocity is

3D time for light (TOF)

The MRA sequence that is least sensitive to flow is

3D time for light (TOF)

The MRA sequence that is most sensitive to smaller vessels is

3D phase contrast MRA (PC MRA)

The MRA sequence that is sensitive to flow direction is

D. A and B

The SNR will increase in a 3D sequence with an increase in A. FOV B. Number of slices C. TE D. A and B

Chemical shift

The basic MR principal with regard to MR spectroscopy is

Image contrast

The effective TE in a fast an echo pulse sequence determines the

D. Short axis single slice, single phase

The evaluation of cardiac function can be provided by any or all of the following EXCEPT A. period cardiac ciné B. Multi phase imaging C. Perfusion imaging D. Short access single shot, single face

D. B 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

Frequency encoding gradient/read out gradient

The gradient that is on during the production of the echo is called the

Frequency

The gradient that is on during the production of the echo is the

The BOLD effect

The intrinsic contrast mechanism with regard to fMRI is

Eliminate the T2 shine three

The main purpose of producing/calculating an ADC map (image) is to

#PEs/ETL

The number of shots is calculated by

Prior to excitation pulses

The presaturation pulses usually occur

Spatial preseparation

The removal of signal from vessels in an MRA sequence is achieved by

TR x NSA x number of phase encodings x number of slices

The scan time for a 3D (or volume) acquisition is given by

Velocity induced phase shift

The signal intensity on PC MRI sequences is related to

Flow-related enhancement

The signal intensity on TOF MRA sequences is related to

Amount of diffusion

The signal intensity on diffusion sequences is related to

Vortex flow

The swirling blood flow that occurs just passed the area of a stenosis is known as

Fourier transformation

The technique by which signal data is modified from the "time domain" to the "frequency domain" is known as

Fourier transformation

The technique by which signal data is transformed from a plot of signal intensity over time to a plot of signal intensity over frequency is known as

interleaved acquisition

The technique whereby a portion of the lines of K-space are "sampled" and "filled" and the remaining lines are interpolated is known as all of the following EXCEPT A. Half Fourier B. Partial Fourier C. Fractional Fourier D. Interleaved acquisition

TR

The time between excitation pulses is known as

Increases with a reduction in receiver bandwidth

The time during which the frequency encoding gradient is on:

Bottom

The top portion of K-space is a mirror image of day

Spoiling

When a gradient echo sequence is acquired for dynamic contrast enhanced imaging of the liver, ____________ is performed

Gradient echo EPI

When acquiring and fMRI series to map out the visual cortex, which of the following pulse sequences would be utilized in order to maximize sensitivity to the BOLD effect

Superior

When doing an MRA of the IVC, a saturation band should be placed ___________ to the axial slice

Superior

When doing an MRA of the carotid arteries, a saturation band should be placed ___________ to the axial slices

Superior

When doing an MRA of the circle of Willis, a saturation band should be placed ____________ to the axial slices

Inferior

When doing an MRV of the superior sagittal sinus, a saturation band should be placed ___________ to the axial slices

Calibration scan

When parallel imaging techniques are performed, a low resolution ___________ ______is required prior to the acquisition

Reduced MR signal

When performing a dynamic perfusion exam of the brain utilizing a gadolinium based MR contrast agent, the result of the T2* shortening is

Patient's heart rate

When triggering a scan from the patient's ECG, the TR of the sequence is determined by the

SNR is reduced and spatial resolution is unaffected

When using parallel imaging to reduce acquisition times, which of the following is always true

A "train" of Gradient echoes

Which of the following best describes a EPI sequence

A 90° post followed by a 180° pulse

Which of the following best describes a SE sequence

A "train" of spin echoes

Which of the following best describes an FSE sequence

A 180° post followed by a 90°/180° combination

Which of the following best describes and IR sequence

A. 0.25 T

Which of the following fields strengths would require the shortest (lowest) T1 time to suppressed/null the signal from fat when acquiring a STIR sequence in an MR exam of the knee? A 0.35 T B. 1.0 T C. 1.5 T D. 3.0 T

b-value 1100

Which of the following would result in an image with the greatest amount of diffusion waiting

8

With a fast been Echo sequence utilizing an eight Echo train linked (ETL), the number of lines of K-space field during each TR will be

TR period

With conventional spin Echo each "line" of K-space is filled in each


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