Review Questions for MRI Part C
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