Data Acquisition and Processing
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:
Centric
The high frequency (low amplitude) data points in k space provide:
Edge detail (spatial resolution)
The main purpose of producing / calculating an ADC map is to
Eliminate the T2 shine through
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:
Elliptic centric
The SNR will increase in a 3D sequence with an increase in
FOV and number of slices
A short T1 inversion recovery (STIR) sequence can suppress the signal from:
Fat and water
STIR sequences can suppress the signal from all of the following except: 1. Fat within bone marrow 2. Gadolinium enhancing lesions 3. retro-orbital fat 4. Fluid (CSF)
Fluid (CSF)
Short tau inversion recovery (STIR) sequences are typically used for the evaluation of all of the following except: 1. Musculoskeletal contusions 2. Fat Suppression 3. Lesions within the retro-orbital fat 4. Fluid (CSF)
Fluid (CSF)
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:
Fourier Transformation
The technique by which signal data is modified from the "time domain" to the "frequency domain" is known as
Fourier transformation
One direction in k space represents phase, while the other represents:
Frequency
The gradient that is on during the production of the echo is the:
Frequency
The readout gradient is also known as the
Frequency
Gradient echo sequences acquired for high signal from fluid are known as all of the following except: 1. Coherent gradient echo 2. incoherent gradient echo 3. steady state gradient echo 4. T2* gradient echo
Incoherent gradient echo
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: 1. Half fourier 2. Partial fourier 3. Fraction fourier 4. Interleaved acquisition
Interleaved acquisition
Creating additional images in various planes from a 3D dataset is accomplished by a technique known as:
MPR
To create a projection image in MRA, the technique most commonly employed is:
Maximum intensity pixel
Increasing the TE yields images with: 1. More T1 information 2. Less T1 information 3. More T2 information 4. Less T2 information
More T2 information
cardiac analysis performed with a technique using SAT bands to assess wall motion is known as:
Myocardial tagging
A single shot FSE sequence is acquired when PE = _____ and ETL = _____
PE= 256 and ETL = 256
A chemical or spectral fat suppression sequence will suppress the signal from fat based on the
Precessional frequency of fat
Parallel imaging techniques are also known as all of the following except: 1. SENSE 2. SMASH 3. GRAPPA 4. SAT
SAT
When using parallel imaging to reduce acquisition times, which of the following is always true?
SNR is reduced and spatial resolution is unaffected
The following is important in MRA sequences to minimize the loss of signal due to dephasing within a voxel:
Small vessels and Short TE
When a gradient echo sequence is acquired for dynamic contrast - enhanced imaging of the liver, __________________________ is performed.
Spoiling
The removal of signal from vessels in an MRA sequence is achieved by:
Spatial presaturation
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:
Steady State
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?
Tissues or substances with extremely short T2 relaxation times.
Gradient echo sequences use flip angles:
To control saturation effects
Fourier Transformation converts signal data from the FID into the spectrum true or false
True
Gradient echo sequences can yield either T1 or T2* characteristics true or false?
True
Normal blood flow is known as:
Turbulent flow
To produce the echo, a gradient echo pulse sequence uses a:
combination of gradient magnetic field and RF pulse
In a time of flight sequence, flowing blood is HYPERintense relative to stationary tissue because of the:
flow related enhancement
The signal intensity on TOF MRA sequences is related to:
flow- related enhancement
The effective TE in a fast spin echo pulse sequence determines the
image contrast
Each "frame" of a cardiac cine sequence displays the heart:
in different phases of the cardiac cycle
A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as:
incoherent/ spoiled
Using a conventional spin echo multislice sequence, the number of slices allowed when increasing the TR
increase by a factor of TR/TE
Doubling the NSA will ______________________ the SNR by ________________
increase, square root of 2
Decreasing the receiver bandwidth (narrow BW) _____________________ readout time
increases
Decreasing the receiver bandwidth (narrow BW) _____________________ susceptibility artifact
increases
Increasing the NSA _______________ scan time
increases
Increasing the phase matrix ________________ scan time
increases
Reducing the ETL _______ scan time
increases
Reducing the TE ___________ SNR
increases
The time during which the frequency encoding gradient is on _____________________ with a reduction in receiver bandwidth
increases
increasing the slice thickness ______________ SNR
increases
Increasing the flip angle ____________ SNR
increases SNR up to the Ernst angle
Increasing the TE:
increases the contrast based on the T2 relaxation of the tissues
As the TR increases: SNR _____________________
increases up to a point
Increasing the slice thickness from 5 to 10 mm, the SNR ___________________ by a factor of ____
increases, 2
When doing an MRV of the superior sagittal sinus, a sat band should be placed ____________________ to the axial slices
inferior
Using a 3D acquisition, the number of slices allowed when increasing the TR
is not affected
In order to produce a high quality reformatted image, the voxel should be
isotropic
Increasing the TR _________________ scan time
Increases scan time
The number of shots is calculated by
#PE's / ETL
Which of the following field strengths would require the shortest (lowest) T1 time to suppress/ null the signal from fat when acquiring a STIR sequence in an MR exam of the knee? 1. .35T 2. 1.0T 3. 1.5T 4. 3.0T
.35T
Doubling the NSA will increase the SNR by a factor of
1.41
In a spin echo sequence, the time between the 90 and 180 is
1/2 TE
An inversion recovery spin echo sequence begins with a:
180 RF pulse
A typical inversion recovery spin echo uses pulses:
180, 90, 180
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:
2 minutes
If a phase resolution of 256 is desired, then the TR must be repeated (for one NSA)
256 times
The MRA sequence that is least sensitive to slow flow is:
3D TOF
The MRA sequence that is most sensitive to smaller vessels is:
3D TOF
The MRA sequence that is sensitive to flow direction is:
3D phase contrast (PC MRA)
The MRA sequence that can be made sensitive to any flow velocity is:
3D phase contrast MRA (PC MRA)
Reducing the FOV by a factor of 2 will reduce the voxel volume by a factor of
4
In a fast spin echo pulse sequence, if the echo trail length is increased by a factor of four, then the scan will be _____ times as fast
4 times
A FLAIR sequence is utilized to suppress the signal from:
CSF
If one desires to null 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.
69%
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:
8
A typical spin echo sequence uses pulses:
90 and 180
Cardiac cine acquisitions typically utilize a / an __________________ pulse sequence.
A gradient echo pulse sequence
in a 3D acquisition, the slices are produced by:
A phase encoding gradient applied in the slice selection direction
Single order gradient moment nulling does not compensate for
Accelerated flow and reverse flow
Which technique can be utilized to optimally time the start of a contrast- enhanced MRA
Automated bolus detection, test bolus, and real time / fluoro triggering
The top portion of k space is a mirror image of the:
Bottom
During dynamic enhanced imaging for vasculature or visceral structures, contrast is administered and k space is filled with _____________ to ensure that the contrast enhancement is well visualized.
Centric
The basic MR principle with regard to MR spectroscopy is:
Chemical shift
To evaluate the COW, 3D TOF MRA sequences are acquired and displayed as an axial view of all of the vasculature. This image is known as:
Collapsed Image
Reducing NSA will reduce the scan time and ___________________ the SNR
Decrease the SNR
Decreasing the receiver bandwidth (narrow BW) _______________ number of slices
Decreases
Using a conventional spin echo sequence, the number of slices allowed when increasing the TE from 20 to 40 ms:
Decreases
Reducing the TR down to or below the T1 relaxation time of the tissue
Decreases the signal to noise ratio of the image and increases saturation effects
between slices 2D acquisitions generally require:
Gaps
to rephrase the signal from moving spins, gradient moment nulling techniques use a
Gradient
When acquiring an 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? 1. Spin Echo EPI 2. Gradient echo EPI 3. Fast spin echo with driven equilibrium 4. 3D spoiled GRE with MTC
Gradient echo EPI
Acquiring half of the phase views of k space and then interpolating the data for the other half is a technique known as:
Half fourier
In a fast spin echo sequence, spatial resolution is associated with the
High amplitude phase encoding gradients
Dynamic enhanced MRA sequences of the renal arteries are performed with the use of:
Incoherent gradient echos
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:
Increased
Decreasing the receiver bandwidth (narrow BW) ___________________ the SNR
Increases
Decreasing the receiver bandwidth (narrow BW) ______________________ chemical shift artifact
Increases
Normal blood flow (demonstrated by a parabolic blood flow profile) is known as:
Laminar Flow
Increasing the TR yields images with: 1. More T1 information 2. Less T1 information 3. More T2 information 4. Less T2 information
Less T1 information
Reducing the flip angle yields images with: 1. More T1 information 2. Less T1 information 3. More T2 information 4. Less T2 information
Less T1 information
Reducing the TE yields images with 1. more T1 information 2. less T1 information 3. more T2 information 4. less T2 information
Less T2 information
In a fast spin echo (FSE) sequence, acquired with long effective TE, scan time can be reduced by the selection of:
Longer ETL
Complete saturation is a condition where:
Longitudinal magnetization is not allowed to recover between excitations
In a fast spin echo sequence, the effective TE is the echo that is performed with the:
Low amplitude phase encoding gradients
Phase encoding is performed: 1. After frequency encoding 2. Prior to frequency encoding 3. In place of frequency encoding 4. During frequency encoding
Prior to frequency encoding
The presaturation pulses usually occur:
Prior to the excitation pulse
Reducing the TE
Reduces contrast based on T2 relaxation times
In order to reconstruct an image acquired using parallel imaging, which of the following may be required?
Reference or calibration scan
In a gradient echo sequence, reducing the flip angle while holding the TR constant reduces:
Saturation
In a time of flight sequence, the tissue is HYPOintense relative to flowing blood because of the:
Saturation effects
To evaluate the COW, 3D TOF MRA sequences are acquired and background tissue is carved out to provide a better visualization of the intracranial vasculature. This step is known as
Segmenting
The evaluation of cardiac function can be provided by any or all of the following except: 1. Cardiac cine 2. Multiphase imaging 3. Perfusion imaging 4. Short axis single slice, single phase
Short axis single slice, single phase
In a fast spin echo (FSE) sequence, acquired with short effective TE, blurring can be reduced by the selection of:
Shorter ETL
To keep scan time at a minimum, diffusion imaging is typically performed with:
Single shot EPI acquisition
During contrast enhanced imaging of the abdominal organs, images are acquired without and with gad enhancement. To better visualize contrast enhancement, _____________________ can be performed.
Subtraction
When doing an MRA of the IVC, a saturation band should be placed ________________ to the axial slices
Superior
When doing an MRA of the carotid arteries, a sat band should be placed _________________ to the axial slices
Superior
Gradient echo sequences acquired for the evaluation of hemorrhagic lesions rely on:
Susceptibility
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:
T1
In a conventional spin echo multi echo sequence, it is possible to create multiple images, each with different amounts of ______ weighting
T2
In which of the following sequences would MS plaque appear hyperintense relative to both CSF and normal white matter? 1. T2 FLAIR 2. T1 FLAIR 3. T2 FSE 4. T2 FSE with RF fat suppression
T2 FLAIR
In a spin echo sequence, flowing blood is normally seen as a signal void because the:
TE is too long to image flow 90 pulse and 180 pulse are both slice selective
In an inversion recovery pulse sequence, the time between the initializing 180 pulse and the 90 pulse is known as:
TI
The time between excitation pulses is known as the:
TR
With conventional spin echo each line of k space is filled in each:
TR period
Scan time for EPI pulse sequences can be calculated by:
TR x #shots x NSA
In a 2D conventional spin echo multislice pulse sequence, scan time is given by the equation:
TR x NSA x PE
The scan time for a 3D acquisition is given by:
TR x NSA x PE x # of slices
In a volume acquisition, the scan time is
TR x NSA x PE x #slices
Scan time for 2D GRE pulse sequences can be calculated by:
TR x PE x NSA
Scan time for 2D IR pulse sequences can be calculated by:
TR x PE x NSA
Scan time for 2D SE pulse sequences can be calculated by
TR x PE x NSA
Scan time for 2D FSE pulse sequences can be calculated by:
TR x PE x NSA/ETL
Scan time for a volume acquisition can be calculated by:
TR x PE's x NSA x #slices
In an inversion recovery pulse sequence, image contrast is controlled by
TR, TE, and TI
Another name for TI is:
Tau
A 3D dataset can be reconstructed to display "what appears to be" a 3D image of the anatomy. This technique is known as
VR- volume rendering
The signal intensity on PC MRA sequences is related to:
Velocity induced phase shift
The swirling blood flow that occurs just past the area of stenosis is known as
Vortex flow
Which of the following best describes an IR sequence? 1. a 90 pulse followed by a 180 pulse 2. a 180 pulse followed by a 90/180 combination 3. a train of gradient echoes 4. a train of spin echoes
a 180 pulse followed by a 90/180 combination
Which of the following best describes a SE sequence? 1. a 90 pulse followed by a 180 pulse 2. a 180 pulse followed by a 90/180 combination 3. a train of gradient echoes 4. a train of spin echoes
a 90 pulse followed by a 180 pulse
Which of the following describes an EPI sequence? 1. a 90 pulse followed by a 180 pulse 2. a 180 pulse followed by a 90/180 combination 3. a train of gradient echoes 4. a train of spin echoes
a train of gradient echoes
Which of the following best describes a FSE sequence? 1 a 90 pulse followed by a 180 pulse 2. a 180 pulse followed by a 90/180 combination 3. a train of gradient echoes 4. a train of spin echoes
a train of spin echoes
When parallel imaging techniques are performed, a low resolution ________________ scan is acquired prior to the acquisition:
calibration
Blood flow at the area of stenosis (vascular narrowing)is known as:
accelerated flow
A typical gradient echo sequence begins with a:
alpha pulse that varies with desired image contrast
The signal intensity on diffusion sequences is related to:
amount of diffusion
Changing the b value alters the
amplitude, timing, and or duration of the diffusion gradients
Fourier Transformation is performed in the
array processor
Blood flow velocities are greatest
at the center of the vessel
Which of the following would result in an image with the greatest amount of diffusion weighting
b value 1100
Increasing the number of phase encodings will produce an image with _______________ voxel volume
decreased
As the TE increases, SNR __________________
decreases
Increasing the matrix ______________ SNR
decreases
Increasing the number of phase encodings from 128 to 256, the SNR
decreases
In a phase contrast technique, it is possible to use the data to determine the:
direction of blood flow
Increasing the FOV ___________ scan time
does not affect
Increasing the number of slices in a 2D acquisition _________________ scan time
does not affect
Increasing the TE _________________ scan time
does not affect scan time
Using a 3D acquisition, increasing the number of slices from 64 to 128 ___________________ scan time
doubles scan time
In a fast spin echo sequence, the central lines of k space are associated with the
effective TE
For a given tissue with a given T1 relaxation time and TR, the flip angle, which will result in the maximum signal for that tissue, is
ernst angle
The gradient that is on during the production of the echo is called the:
frequency encoding gradient
Increasing the receiver bandwidth ______________ the available ETL
has no effect
Increasing the matrix in the frequency direction from 256 to 512 will __________________ scan time
have no effect on the scan time
A major advantage of a 2D TOF sequence over a 3D TOF sequence is the ability to
image a larger area without saturation of the flowing blood
Increasing the flip angle yields images with
more T1 information
Reducing the TR yields images with 1. More T1 information 2. Less T1 information 3. More T2 information 4. Less T2 information
more T1 information
In choosing the direction of phase encoding, the technologist usually considers the direction in which the
motion artifacts traverse the least tissue or areas of interest.
A major advantage of MRA over conventional angiography is that:
multiple views can be produced from a single acquisition
When triggering a scan from the patient's ECG, the TR of the sequence is determined by the
patient's HR
T2 weighted fluid attenuated inversion recovery (FLAIR) sequences are typically used for the evaluation of
periventricular white matter disease
Presaturation pulses are often used to:
reduce flow artifacts
When performing a dynamic perfusion exam of the brain utilizing a gadolinium based MR contrast agent, the result of the T2* shortening is:
reduced MR signal
The 180 pulse that follows the initial 90 pulse in a spin echo sequence will cause the NMR signal to reappear while correcting for:
slight magnetic field inhomogeneities, chemical shift, slight magnetic susceptibility effects
Gradient moment nulling is most effective when correcting for motion induced signal loss from
slow constant flow
When doing an MRA of the COW, a sat band should be placed __________________ to the axial slices.
superior
The intrinsic contrast mechanism with regard to fMRI is:
the BOLD effect
Phase contrast techniques produce images in which the signal intensity within the vessel is dependent on (among other parameters) the:
velocity of the flowing blood
Cine studies are often performed on various joints. The main purpose of such a study is to:
visualize motion and function
A major advantage of 3D TOF techniques over 2D TOF is the ability to
visualize smaller vessels
In a balanced GRE acquisition, the contrast weighting is: 1. T1 weighted 2. T2 weighted 3. T2* weighted 4. Weighted for the ratio of T2/T1
weighted for the ratio of T2/T1
