MRI MCQ for book
In which of the following sequences is all the transverse magnetization rewound at the end of each TR period? a)Coherent gradient echo b)Incoherent gradient echo c)EPI
a
Of the following parameters, which would give the best spatial resolution? a)256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX b)256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX c)512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX
a
Using a long TE enhances T2 and T2* contrast. a)true b)false
a
When the number of signal averages is doubled, by how much does the scan time change? a)× 2 b)1/2 c)22 d)√2
a
Which of these is a consequence of decreasing the TR from 2500 ms to 500 ms? a)Scan time decreases b)T1 weighting decreases c)Spatial resolution decreases d)Slice number available increases
a
Combining a low flip and long TR results in saturation. a)true b)false
b
Of the following parameters, which would give the highest SNR? a)256 × 256, 3 mm slice thickness, 12 cm FOV, 1 NEX b)256 × 128, 8 mm slice thickness, 40 cm FOV, 4 NEX c)512 × 256, 6 mm slice thickness, 14 cm FOV, 2 NEX
b
Which of the following does NOT occur when the receive bandwidth is reduced? a)SNR increases b)Chemical shift artefact improves c)Number of slices available decreases d)TE increases
b
Which of the following statements about partial averaging is true? a)All the lines of K space are filled b)A percentage of lines are filled and the rest is filled with zeroes c)A percentage of the lines are filled and this is used to extrapolate the missing data d)None of the lines are filled
b
Which of these is a consequence of decreasing the phase matrix? a)Truncation artefact improves b)SNR increases c)Spatial resolution increases d)Scan time increases
b
Halving a square FOV reduces the SNR by: a)1/2 b)1/4 c)3/4 d)1/8
c
In terms of the events that take place during an MRI pulse sequence, what factor determines the frequency matrix? a)Slope of frequency encoding gradient b)Sampling time c)The number of data points in each line d)The sampling frequency
c
Which of the following statements is true in an incoherent gradient echo sequence? a)Residual transverse magnetization has the same phase as the magnetization most recently created b)The flip angle is always 10° c)The system discriminates between residual and the most recently created transverse magnetization because it has a different phase value d)It is not a steady state sequence
c
Which TWO factors from the following list affect slice thickness? a)Slew rate of the slice select gradient b)Polarity of slice select gradient c)Slope of slice select gradient d)Duration of slice select gradient e)Power of transmitted RF f)Duration of transmitted RF g)Frequency of transmitted RF h)Bandwidth of transmitted RF i)Amplitude of transmitted RF
c & h
Doubling the number of signal averages changes the SNR by how much? a)× 2 b)1/2 c)22 d)√2
d
Increasing the field strength increases SNR because: a)the flip angle increases b)the NMV increases in size because the high energy population of spins increases c)the precessional frequency increases d)the NMV increases in size because the low energy population of spins increases
d
Which of the following statements about partial echo is true? a)All of K space is filled b)The right-hand side of K space is filled but the left is filled with zeroes c)The left-hand side is filled and the right is filled with zeroes d)The right-hand side is filled and data from this is extrapolated and placed in the left-hand side of K space
d
Which of these is NOT a consequence of decreasing the TR from 2500 ms to 500 ms? a)Scan time decreases b)T1 weighting increases c)Slice number available decreases d)SNR increases
d
Which of these is NOT a consequence of decreasing the phase matrix? a)SNR increases b)Spatial resolution decreases c)Truncation artefact gets worse d)Scan time increases
d
