When doing a study on a patient's knee you notice that the image is fuzzy (TOO MUCH PARTIAL VOLUME AVERAGING). Which of the following changes would improve your image the most when repeating the sequence? correct answersDecreasing the thickness 1/2 mm
If we have a voxel of .78mm x .78mm x .1mm, ...
When doing a study on a patient's knee you notice that the image is fuzzy (TOO MUCH PARTIAL VOLUME
AVERAGING). Which of the following changes would improve your image the most when repeating the
sequence? correct answersDecreasing the thickness 1/2 mm
If we have a voxel of .78mm x .78mm x .1mm, we would have an anisotropic voxel? correct answersTrue
If you change the NEX from 2 to 4, what is the resulting scan time change? correct answers2x
Which of these is NOT a consequence of decreasing the TR from 2500ms to 500ms? correct answersSNR
increases
What is the voxel volume for the following parameters?
The size of the receiver coil should be chosen such that the volume of tissue images optimally fills the
sensitive volume of the coil. correct answersTrue
If you have a frequency of 256, phase of 192 and FOV 200mm, what would be the pixel size? correct
answers.78mm x 1.04mm
So you are doing an MRI exam and you need to change 1 of the factors to improve SNR. Which of the
following has the greatest factor of improving the SNR? correct answersFOV
, All of the following affect SNR except: correct answersScan time
Phased array coils decrease SNR as the data from several coils are not added together. correct
answersFalse
Long TR decreases SNR and a short TR increases SNR correct answersFalse
Changing the slice thickness from 4mm to 3mm results in a thinner slice which has a lower SNR correct
answersTrue
To double the SNR, we need to increase the NEX and scan time by how much? correct answers4 times
If we changed the NEX from 1 to 2, the SNR is increasing how much? correct answers40%
When the NEX is doubled, how much does the resulting scan time change? correct answers2x
Which of the following aspects is also changed when we add slices to our sequence? correct
answersScan time
Increasing the field strength increases SNR because: correct answersThe NMV increases in size because
the low energy population of spins increases
Reducing the receive bandwidth increase the SNR, and reduced the noise that is sampled. correct
answersTrue
If FOV is rectangular, the pixels will be square if the matrix selected produces a pixel with the same
dimensions along phases as well as frequency directions. correct answersTrue
If you change your FOV from 12cm to 24cm, how much is the SNR increasing? correct answers4x
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