MRI Registry Exam Questions and Answers 100% Pass
gradient rise time - Answers the time it takes for the gradient to reach its full amplitude
gradient slew rate - Answers the speed rate of ascent or descent of a gradient from zero to its maximum
amplitude,
duty cycle - Answers the time the gradients are on during a TR period, the "gradient working time."
A 6 inch surface coil is able to receive how much signal ? - Answers 3 inches
When going from a linear coil to a quadrature coil, SNR is increased by - Answers 40%.
The intensity limit for a static magnetic field in clinical use is limited by the Food and Drug
Administration (FDA) to ? - Answers 4.0 Tesla (T) field strength for all patients, but 8 Tesla for all patients
over 1 month of age.
The liquid cryogens are cooled in superconducting magnet at a temperature of? - Answers 4º Kelvin.
Consistent room temperature of _____, humidity of ________, and sufficient air flow in the MR scan
room is recommended to make patients less vulnerable to the RF heating effects. - Answers 65-75°F, 50-
70%
Which sequences can have more of a detrimental effect on patients with regards to time varying
magnetic fields? - Answers EPI (Echo Planar Imaging)
Oscillating magnetic fields (radiofrequency) primary biological effect is? - Answers ..tissue heating
/deposition.
The resonance frequency in a 1.5 Tesla magnet is? - Answers 63.86 Mhz.
The difference in chemical shift is approximately ? - Answers 3.5 parts-per-million (ppm)
1 Tesla 147hz (1.5Tesla - 220 Hz 3Tesla - 440 Hz)
T1 relaxation occurs when nuclei give up their energy to the surrounding tissue, which is known as? -
Answers spin lattice relaxation
T1 relaxation (recovery) time is the recovery of ____% longitudinal magnetization - Answers 63%
T2 relaxation (Decay) time is defined as the time it takes for ___% of the transverse magnetization to
decay, - Answers 63% or to de-phase to 37% of their original value
The return of the transverse magnetization to its equilibrium value, zero (T2 decay) - Answers Spin-spin
relaxation -
, Hydrogen in fat recovers more rapidly along the longitudinal axis than water and loses transverse
magnetization faster than water - Answers ...
When increasing NEX/NSA, SNR (signal-to-noise ratio) increases by the? - Answers square root (√) of the
% increase. 2 NEX, increased to 6 NEX (3times the total NEX) would have an increase in SNR of √3,
A method of reducing MRI scan time by not filling as many lines of k-space in the phase direction, while
maintaining spatial resolution, is known as - Answers Rectangular FOV
What is defined as the storage location of MR signal data? - Answers k-space
Referring to k-space, the data containing high resolution are located along the ? - Answers outer lines
Referring to k-space, the data containing signal and contrast information are located along the? -
Answers central lines.
High amplitude signals are stored in what part of k-space? - Answers center
Acquiring a bit more than half the phase dimension k-space samples, then
interpolating the data with zeroes for the remaining half is a technique known as ? - Answers Half
Fourier, or Zero Fill.
what is when only half the views of k-space are filled in the frequency axis, an acceleration technique
used to shorten TR and TE? - Answers Partial or fractional echo
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 - Answers elliptic centric k-space filling
The high amplitude signals are stored in the center of k-space, where ______information is also found. -
Answers contrast/max signal
what sequence usually require an interslice gap? - Answers 2D acquisitions
Which sequence provides greater SNR and elimination of crosstalk artifacts? - Answers 3D sequence
does
Which sequence is best for reconstruct of multiple planes - Answers 3D pulse sequence due to the thin
slices used and the absence of an interslice gap.
What is defined as a small change in the magnetic field along a particular axis? - Answers A gradient
bandwidth, has a direct relationship to SNR: decreasing bandwidth by factor of 2 increases SNR by? -
Answers ... √2
Increasing Receiver Bandwidth:
gradient rise time - Answers the time it takes for the gradient to reach its full amplitude
gradient slew rate - Answers the speed rate of ascent or descent of a gradient from zero to its maximum
amplitude,
duty cycle - Answers the time the gradients are on during a TR period, the "gradient working time."
A 6 inch surface coil is able to receive how much signal ? - Answers 3 inches
When going from a linear coil to a quadrature coil, SNR is increased by - Answers 40%.
The intensity limit for a static magnetic field in clinical use is limited by the Food and Drug
Administration (FDA) to ? - Answers 4.0 Tesla (T) field strength for all patients, but 8 Tesla for all patients
over 1 month of age.
The liquid cryogens are cooled in superconducting magnet at a temperature of? - Answers 4º Kelvin.
Consistent room temperature of _____, humidity of ________, and sufficient air flow in the MR scan
room is recommended to make patients less vulnerable to the RF heating effects. - Answers 65-75°F, 50-
70%
Which sequences can have more of a detrimental effect on patients with regards to time varying
magnetic fields? - Answers EPI (Echo Planar Imaging)
Oscillating magnetic fields (radiofrequency) primary biological effect is? - Answers ..tissue heating
/deposition.
The resonance frequency in a 1.5 Tesla magnet is? - Answers 63.86 Mhz.
The difference in chemical shift is approximately ? - Answers 3.5 parts-per-million (ppm)
1 Tesla 147hz (1.5Tesla - 220 Hz 3Tesla - 440 Hz)
T1 relaxation occurs when nuclei give up their energy to the surrounding tissue, which is known as? -
Answers spin lattice relaxation
T1 relaxation (recovery) time is the recovery of ____% longitudinal magnetization - Answers 63%
T2 relaxation (Decay) time is defined as the time it takes for ___% of the transverse magnetization to
decay, - Answers 63% or to de-phase to 37% of their original value
The return of the transverse magnetization to its equilibrium value, zero (T2 decay) - Answers Spin-spin
relaxation -
, Hydrogen in fat recovers more rapidly along the longitudinal axis than water and loses transverse
magnetization faster than water - Answers ...
When increasing NEX/NSA, SNR (signal-to-noise ratio) increases by the? - Answers square root (√) of the
% increase. 2 NEX, increased to 6 NEX (3times the total NEX) would have an increase in SNR of √3,
A method of reducing MRI scan time by not filling as many lines of k-space in the phase direction, while
maintaining spatial resolution, is known as - Answers Rectangular FOV
What is defined as the storage location of MR signal data? - Answers k-space
Referring to k-space, the data containing high resolution are located along the ? - Answers outer lines
Referring to k-space, the data containing signal and contrast information are located along the? -
Answers central lines.
High amplitude signals are stored in what part of k-space? - Answers center
Acquiring a bit more than half the phase dimension k-space samples, then
interpolating the data with zeroes for the remaining half is a technique known as ? - Answers Half
Fourier, or Zero Fill.
what is when only half the views of k-space are filled in the frequency axis, an acceleration technique
used to shorten TR and TE? - Answers Partial or fractional echo
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 - Answers elliptic centric k-space filling
The high amplitude signals are stored in the center of k-space, where ______information is also found. -
Answers contrast/max signal
what sequence usually require an interslice gap? - Answers 2D acquisitions
Which sequence provides greater SNR and elimination of crosstalk artifacts? - Answers 3D sequence
does
Which sequence is best for reconstruct of multiple planes - Answers 3D pulse sequence due to the thin
slices used and the absence of an interslice gap.
What is defined as a small change in the magnetic field along a particular axis? - Answers A gradient
bandwidth, has a direct relationship to SNR: decreasing bandwidth by factor of 2 increases SNR by? -
Answers ... √2
Increasing Receiver Bandwidth:
