An image artifact caused by anatomical motion along a gradient is known as what type of artifact
Ringing
Aliasing
Volume averaging
Phase mismapping
Another name for phase mismapping artifact is
Ghosting
Truncation
An example ofphase mismapping artifact is
Cardiac motion
Flow motion
Respiratory motion
Cardiac motion & Flow motion & Respiratory motion
An example of aperiodic motion is
Peristalsis motion
Ghosting artifact on an MR image caused by the heart can be decreased by which of the following methods
Decreasing bandwidth
Peripheral compensation
Cardiac gating
Respiratory compensation
Motion artifact on an MR image caused by flowing blood or CSF can be decreased by which of the following methods
Respiratory compensaton
Patient education
Gradient moment nulling
Respiratory gating
Peripheral gating is a technique used to decrease what type of motion artifact
CSF pulsation motion
Swallowing
A saturation pulse is a technique used to reduce what type of motion artifact
Blood flow motion
Swallowing motion
All of the above
Phase mismapping artifact always occurs in which direction of the MR image
Frequency direction
Phase direction
Slice selection direction
Readout direction
Phase mismapping artifact caused by respiratory motion can be decreased by which method
Presaturation pulse
Swapping phase and frequency direction
Gradient moment nulling is most effective in reducing flow related motion in which type of flow
Slow flow
Fast flow
Inplane flow
Slow flow and inplane flow
The artifact that is produced when anatomy that is outside the FOV is mapped within the FOV is known as
Partial volume averaging
Magnetic susceptibility
Another name for aliasing artifact is
Foldover artifact
Ringing artifact
Wraparound artifact
Foldover artifact & Wraparound artifact
Wraparound artifact occurs in which direction of an MR image
Phase direction & Frequency direction
Wraparound artifact caused by undersampling of frequencies in the readout direction is known as
Phase wrap
Frequency wrap
Gibbs wrap
Foldover artifact caused by undersampling of signal in the phase encoding direction is known as
None of the above
Aliasing artifact in the frequency direction can be corrected by which of the following methods
Decreasing the FOV
Increasing the matrix
Filtering the frequencies outside the FOV in the phase direction
Filtering the frequencies outside the FOV in the frequency direction
Foldover artifact in the phase direction can be corrected by which of the following methods
Oversampling the signal outside the FOV
Increasing the FOV
Using saturation pulses outside the FOV
The precessional frequency of hydrogen is influenced by its chemical environment
True
False
In fat, the hydrogen atom is bound with what other type of atom
Oxygen
Nitrogen
Helium
Carbon
In water, the hydrogen atom is bound with what other type of atom
The artifact that is caused due to the difference in precessional frequencies between fat and water is called
Chemical shift
In a 1.5 tesla magnet, the difference in the precessional frequency between fat and water is
250 MHz
210 MHz
220 Watts
220 Hz
In a 1.0 tesla magnet, the difference in the precessional frequency between fat and water is
130 MHz
147 Hz
200 Hz
Chemical shift artifact occurs in which direction of the MR image
Phase encoding direction
Frequency encoding direction
In an MR image, the degree of chemical shift artifact depends upon which parameter
Receive bandwidth
Size of the FOV
Magnetic field strength
Chemical shift artifact can be minimized by which of the following methods
Minimizing the FOV
Increasing the receive bandwidth
Utilizing chemical saturation
The artifact that is caused by the phase differences between fat and water is known as
Chemical misregistration
Chemical misregistration artifact most commonly occurs in which direction of the MR image
Chemical misregistration artifact is most likely to affect which type of pulse sequence
Spin echo pulse sequences
Inversion recovery pulse sequences
Gradient echo pulse sequences
Which imaging parameter affects the amount of chemical misregistration that will be seen on an image
TR
TI
TE
NEX
At 1.5 tesla, to reduce chemical misregistration artifact, the TE should be a multiple of what time
3.1 ms
4.2 ms
6.6 ms
7.3 ms
At 0.5 tesla, to reduce chemical misregistration artifact, the TE should be a multiple of what time
7.0 ms
The time that both fat and water are in phase with each other is known as
Peroidicity
Repetition time
Inversion time
Another name for truncation artifact is
Gibbs artifact
Gibbs artifact & Ringing artifact
The artifact that appears as a low intensity band in areas of high intensity due to undersampling is known as
Truncation artifact
Gibbs artifact can be decreased by ________ the number of phase encoding steps
Increasing
Decreasing
Truncation artifact occurs in which direction of the MRl image
Metal in the patient, in the area that is being scanned, will most likely create what type of artifact
Chemical shift artifact
Magnetic susceptability
Magnetic susceptibility artifact is most prominent in what type of pulse sequence
Spin echo
Inversion recovery
Gradient echo
Magnetic susceptibility artifact can be used to help diagnose what pathology
Torn meniscus
Herniated nucleus pulposis
Pituitary adenoma
Hemorrhage
An artifact that is caused by an external radio frequency leak is known as
Shading artifact
Zipper artifact
Starring artifact
Herringbone
In clinical MRI, what method is used to prevent external radio frequency from affecting the MRI image
Copper shielded room
Iron shielded magnet
Passive shimming
The artifact that is produced by overlapping radio frequency pulses in adjacent slices is known as
Cross excitation artifact
Aliasing artifact
Phase mismapping artifact
The artifact produced by the transfer of spin lattice energy from one slice to its adjacent slice is known as
Cross talk artifact
Cross excitation artifact can be eliminated by which ofthe following methods
Increasing interslice gap
Using a sine RF pulse
Interleaving
The technique used to eliminate cross excitation artifact that acquires data in two separate acquisitions from alternating slices is known as
Spin warping
To decrease the chances of cross excitation there should be at least what percentage of interslice gap
10 %
15 %
30 %
50 %
Cross excitation artifact is less likely to occur with which pulse sequence
Spin echo, 90 degree flip angle, 10% interslice gap
Spin echo, 90 degree flip angle, 50% interslice gap
Gradient echo, 15 degree flip angle, 30% interslice gap
Dual echo, 90 degree flip angle, 25% interslice gap
The artifact that is produced when many structures with different signal intensities are averaged together within a pixel is known as
Volume averaging artifact can be reduced by which of the following methods
Increasing slice thickness
Decreasing slice thickness
Increasing NEX
Decreasing NEX
The artifact that is characterized by a loss of signal intensity in one area of an image is known as
Shading artifact can be caused by what factor(s)
Inhomogeneity of the external magnetic field
Undersampling of phase encoding steps
Inhomogeneity of the RF pulse
Inhomogeneity of the external magnetic field & Inhomogeneity of the RF pulse
Data loss due to gradient instability, excessive noise, or tuning errors can cause an artifact with what type of appearance
Zippering
Shading
Staring
An artifact caused by faulty receiver attenuation settings during prescan is known as
Data clipping
Figure 6 - 1 displays an example of what type of artifact?
Foldover
Magnetic Susceptibility
Figure 6-2 displays an example of what type of artifact
RF zipper
Magnetic susceptibility & RF zipper
Figure 6-3 displays an example of what type of artifact
Cross talk
Figure 6-4 displays an example of what type of artifact
Cross excitation
Figure 6-5 displays an example of what type of artifact
Figure 6-6 displays an example of what type of artifact
Figure 6-7 displays an example of what type of artifact
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