MRI Review Questions Pg 248-284
In which of the following EPI sequences would one expect there to be the least susceptibility (distortion) artifacts?
Multi-shot (4 shot) SE, EPI, 256 phase x 256 frequency
In an image acquired with a balanced GRE sequence (Figure C.2), all of the following have high (bright) signal EXCEPT
Normal myocardium
Parallel imaging techniques are also known as all of the following EXCEPT
SAT
Gradient echo sequences can yield either T1 or T2* characteristics True or False
True
When parallel imaging techniques are performed, a low resolution _____ scan is acquired prior to the acquisition
calibration scan
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
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
collapsed image
Dynamic enhanced MRA sequences of the renal arteries are performed with the use of
incoherent gradient echoes
Gradient echo sequences acquired for high signal from fluid are known as all the following EXCEPT
incoherent gradient echoes
A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as
incoherent/spoiled
In a fast spin echo (FSE) sequence, acquired with long effective TE (T2-weighted images), scan time can be reduced by the selection of
longer ETL
When doing an MRV of the superior sagittal sinus, a saturation band should be placed _____ to the axial slices.
inferior
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:
interleaved acquisition
The number of shots is calculated by
#PEs/ETL
The top portion of k-space is a mirror image of the
bottom
Phase encoding is performed
prior to frequency encoding
A single shot FSE sequence is acquired when
#PEs = 256 and ETL = 256
A multi-shot FSE sequence is acquired (with four shots) when:
#PEs = 256 and ETL = 64
Which of the following field strengths would require the shortest (lowest) TI time to suppress/null the signal from fat when acquiring a STIR sequence in an MR exam of the knee?
0.35 T
Acquiring half of the phase views of k-space and then interpolating the data for the other half is a technique known as
12
An inversion recovery (IR) spin echo sequence begins with a
180 degree RF pulse
A typical inversion recovery (IR) spin echo sequence spin echo sequence uses pulses
180 degree, 90 degree, 180 degree
If the pulse sequence shown in Figure C.1 were a fast spin echo sequence, the number of lines of k space filled during each TR period would be
2
In the multi-echo spin echo sequence shown in Figure C.1, the number of images PER SLICE LOCATION created will be
2
If a given conventional spin echo pulse sequence makes 12 minutes to acquire, a fast spin echo sequence using a ETL of six, with all other factors that affect scan time remaining the same, will take
2 minutes
In the multi-echo spin echo sequence shown in Figure C.1, the number of LONG TE images created with a 20-slice 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-slice sequence will be
20
If a phase resolution of 256 is desired, then the TR must be repeated (for one NSA)
256 times
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
40
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 (SE) sequence uses pulses
90 degree, 180 degree
A FLAIR sequence is utilized to suppress the signal from
CSF
In which of the following sequences would MS plaques appear hyper intense relative to both CSF and normal white matter?
T2 FLAIR
In the multi-echo spin echo sequence shown in Figure C.1, images will be acquired with varying amounts of
T2 information
With conventional spin echo each "line" of k-space is filled in each
TR period
Scan time for 2D FSE pulse sequences can be calculated by
TR x #PEs NSA/ETL
Scan time for 2D GRE pulse sequences can be calculated by
TR x #PEs x NSA
Scan time for 2D IR pulse sequences can be calculated by
TR x #PEs x NSA
Scan time for 2D SE pulse sequences can be calculated by
TR x #PEs x NSA
Scan time for a "volume" acquisition can be calculated by
TR x #PEs x NSA x #slices
Scan time for EPI pulse sequences can be calculated by
TR x #shots x NSA
In a volume acquisition, the scan time is
TR x NSA x number of phase encodings x number of slices
The scan time for a 3D (or volume) acquisition is given by
TR x NSA x number of phase encodings x number of slices
Which of the following best describes an EPI sequence ?
a "train" of gradient echoes
Which of the following best describes an FSE sequence?
a "train" of spin echoes
Which of the following best describes an IR sequence?
a 180 degree pulse followed by a 90 degree/180 degree combination
Which of the following best describes a SE sequence?
a 90 degree pulse followed by a 180 degree pulse
In a 3D acquisition, the slices are produced by
a phase-encoding gradient applied in the slice selection direction
In order to produce high-quality reformatted image, the
acquisition voxel should be isotropic
Gradient echo sequences can yield either T1 or T2 characteristics, with influences caused by all of the following EXCEPT
aliasing
A typical gradient echo sequence begins with a
alpha pulse that varies with desired image contrast
STIR sequences can suppress the signal from all of the following EXCEPT:
fluid CSF
Short tau inversion recovery (STIR) sequences are typically used for the evaluation of all of the following EXCEPT:
fluid CSF
In a fast spin echo pulse sequence, if the echo trail length is increased by a factor of four, the scan will be
four times as fast
One direction in k-space represents phase, while the other represents
frequency
The "readout" gradient is also known as the
frequency
The gradient that is on during the production of the echo is the
frequency
The gradient that is on during the production of the echo is called the
frequency encoding gradient/readout 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?
gradient echo EPI
In a fast spin echo sequence, spatial resolution is associated with the
high amplitude phase-encoding gradients
In a fast spin echo sequence, the effective TE is the echo that is performed with the
low amplitude phase-encoding gradients
To create a projection image in MRA, the technique most commonly employed is
maximum intensity pixel
Creating additional images in various planes from a 3D dataset is accomplished by a technique known as
multiplayer reformatting
T2 weighted fluid attenuated inversion recovery (FLAIR) sequences are typically used for the evaluation of
periventricular white matter disease
To evaluate the circle of Willis (COW), 3D TOF MRA sequences are acquired and background tissue is "carved out" to provide better visualization of the intracranial vasculature. This step is known as
segmenting
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
shorter ETL
To keep scan time at a minimum, diffusion imaging is typically performed with
single-shot EPI acquisition
The 180 degree pulse that follows the initial 90 degree 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
When a gradient echo sequence is acquired for dynamic contrast-enhanced imaging of the liver, ______ is performed.
spoiling
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
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 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.
superior
Gradient echo sequences acquired for the evaluation of hemorrhagic lesions rely on
susceptibility
To produce the echo, a gradient echo pulse sequence uses a
switching device
In a balanced GRE acquisition, the contrast weighting is
weighted for the ratio of T2/T1
