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For a given number of slices, which pulse sequence uses the most 180• RF pulses during each TR period?
Dual contrast spin echo
_________ is the fastest imaging technique
Single shot EPI
What type of PS consists of a 180• RF pulse followed by a 90• RF pulse within each TR period?
Inversion recovery
In an inversion recovery PS, the time from the investing pulse to the 90• pulse is called the:
TI
The scan time of a fast spin echo PS with a TR of 3000 ms, 1 signal average, a 256 matrix, and 4 echoes collected for each slice during TR period is ___________ minutes
3.2
In a dual contrast spin echo sequence with echo times of 25 msec and 90 msec, the second echo image has:
More T2 contrast and lower S-N ratio (1&2)
CSF suppression is performed with which type of technique?
FLAIR
Which is the following sequences is best for visualizing hemorrhage?
Gradient echo
Compared to a spin echo pulse sequence, a gradient echo PS:
May use shorter repetition, flip angle is <90• (1&2)
Gradient echo imaging is commonly used for all of the following except:
Ruling out tumours
In the figure shown, which letter corresponds to the echo time for the second echo?
A
MR angiography uses which kind of PS?
Gradient echo
"An EPI sequence in which all of the echoes necessary to reconstruct the image are collected following a single RF excitation:"
Single shot EPI
STIR is used for ________ suppression
Fat
Which of the following sequences is best for cardiac?
Echo planar
A voxel is identical to a single:
3D volume element...
Which PS would you expect to find the shortest TR?
Gradient echo
The pixel size of the images which result from a 3D acquisition using a 280mm FOV, 256x256 matrix, 32 slices, and 64mm ST is:
1.09 x 1.09
A fast spin echo is faster than a conventional spin echo because:
Several echoes...
Which is an advantage of using 3D rather than 2D?
Slices have a greater S-N ratio, no crosstalk (1&2)
MPR are usually reserved for images with a 3D pulse sequence because:
2D slices are too thick, often gaps between 2D slices (2&3)
Which is a characteristic of an isotopic data set?
Voxels are perfect cubes, ST = in plane resolution (1&3)
Which of the following sequences is best for performing diffusion-weighting imaging?
Echo planar imaging
Which of the following is not a benefit of contrast enhanced MRA?
Timing of scan relative...
The scan time of a 3D pulse sequence with 200 phase steps in the image matrix, a TR of 40 ms, 15 slices, and 2 signal averages is ___________ minutes
4
An image acquired with a 3D pulse sequence:
May be used as the base data
The MIP algorithm:
Projects high-intensity pixels...
_______________ MR angiography assists bright pixels to protons that have more phase
Phase contrast
Which MR technique is used to evaluate stroke?
Diffusion-weighted
MRA based images are post-processed with algorithms such as MIPS and volume rendering to:
Show the entire course...
The ___________ of the blood is responsible for the bright blood signal in TOF MRA exams
Flow
The degree of stenosis _______________________ with TOF MRA
May be overestimated
TOF MRA:
12&3
When using phase contrast MR angiography compared to TOF MR angiography:
12&3
An MRA study:
Is at most, minimally invasive
Which is not a metabolic found on 1H spectrum of a normal brain tissue?
Olefin sulfate
Which of the MRA techniques had a scan time short enough to complete an abdominal study in a single breath hold?
Contrast enhanced (3 only)
Which MRA technique demonstrates the actual size of vessel lumen?
Contrast enhanced (2 only)
The final result of a perfusion study is:
Calculated maps which indicate...
The height of a peak on a MR spectrum corresponds to the ___________ of a substance that was detected
Amount