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MRI Final test

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vatixiki's version from 2016-09-13 00:51

Section 1

Question Answer
An image artifact caused by anatomical motion along a gradient is known as what type of artifact?Phase mismapping
An example of phase mismapping artifact is:Cardiac motion, flow motion, and respiratory motion
Ghosting artifact on an MR image caused by the heart can be decreased by which of the following methods?Cardiac gating
Motion artifact on an MR image caused by flowing blood or CSF can be decreased by which of the following methods?Gradient moment nulling
Peripheral gating is a technique used to decrease what type of motion artifact?CSF pulsation motion
A saturation pulse is a technique used to reduce what type of motion artifact??chemical shift
Phase mismapping artifact always occurs in which direction of the MR image?Phase direction
Phase mismapping artifact caused by respiratory motion can be decreased by which method?Presaturation pulse, swapping phase and frequency direction, and respiratory compensation.
memorize

Section 2

Question Answer
Gradient moment nulling is most effective in reducing flow related motion in which type of 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:Aliasing
Another name for aliasing artifact is what?Wraparound artifact
Wraparound artifact occurs in which direction of an MR image?Phase direction and frequency direction
Wraparound artifact caused by undersampling of frequencies in the readout direction is known as:Frequency wrap
Foldover artifact caused by undersampling of signal in the phase encoding direction is known as:Phase wrap
Aliasing artifact in the frequency direction can be corrected by which of the following methods?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 signal outside the FOV, increasing the FOV, and using saturation pulses outside the FOV
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Section 3

Question Answer
The precessional frequency of hydrogen is influenced by its chemical environment.True
In fat, the hydrogen atom is bound with what other type of atom?Carbon
In water, the hydrogen atom is bound with what other type of atom?Oxygen
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:220 Hz
In a 1.0 tesla magnet, the difference in the precessional frequency between fat and water is:147 Hz
Chemical shift artifact occurs in which direction of the MR image?Frequency encoding direction
In an MR image, the degree of chemical shift artifact depends upon which parameter?Receive bandwidth, size of the FOV, and magnetic field strength.
Chemical shift artifact can be minimized by which of the following methods?Minimizing the FOV, increasing the receive bandwidth, and utilizing chemical saturaton
The artifact that is caused by the phase differences between fat and water is known as:Chemical misregistration
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Section 4

Question Answer
Chemical misregistration artifact most commonly occurs in which direction of the MR image?Phase encoding direction
Chemical misregistration artifact is most likely to affect which type of pulse sequence?Gradient echo pulse sequences
Which imaging parameter affects the amount of chemical misregistration that will be seen on an image?TE
Which imaging parameter affects the amount of chemical misregistration that will be seen on an image?Gibbs artifact, and ringing artifact
The artifact that appears as a low intensity band in areas of high intensity due to undersampling is known as:Gibbs artifact, truncation artifact, and ringing artifact.
How can the gibbs artifacts be decreased?By increasing the number of phase encoding steps.
Truncation artifact occurs in which direction of the MRI image?Phase encoding direction
Metal in the patient, in the area that is being scanned, will most likely create what type of artifact?Magnetic susceptability
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Section 5

Question Answer
Magnetic susceptibility artifact is most prominent in what type of pulse sequence?Gradient recovery
Magnetic susceptibility artifact can be used to help diagnose what pathologyHemorrhage
An artifact that is caused by an external radio frequency leak is known as:Zipper artifact
In clinical MRI, what method is used to prevent external radio frequency from affecting the MRI image?Copper shielded room
The artifact that is produced by overlapping radio frequency pulses in adjacent slices is known as:Aliasing 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 of the following methods?Increasing interslice gap, using a sine RF pulse, and interleaving
The technique used to eliminate cross excitation artifact requires data in two separate acquisitions from alternating slices is known as:Interleaving
To decrease the chances of cross excitation there should be at least what percentage of interslice gap?30%
Cross excitation artifact is less likely to occur with which pulse sequence?Gradient echo, 15 degree flip angle, 30% interslice gap
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Section 6

Question Answer
The artifact that is produced when many structures with different signal intensities are averaged together within a pixel is known as:Partial volume averaging
Volume averaging artifact can be reduced by which of the following methods?Decreasing slice thickness
The artifact that is characterized by a loss of signal intensity in one area of an image is known as:Shading artifact
Shading artifact can be caused by what factor(s)?Inhomogeneity of the external magnetic field, and 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?Herringbone
An artifact caused by faulty receiver attenuation settings during prescan is known as:Data clipping
Thorough patient preparation should include which of the following?Proper pt screening, complete pt medical history, and adequate pt education.
Proper patient screening should include which of the following?The elimination of any loose metal objects and personal items, the id of any loose metal objects and personal items, and the id of any biomedical implants.
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Section 7

Question Answer
Complete medical history should include which of the following?Pt age, sex, and weight. Current physical symptoms, and previous surgeries and associated medical problems.
Adequate pt education should include which of the following?Through description of the procedure, and the importance of remaining still.
Ancillary equipment that should be excluded from the magnetic room includes which of the following?Ferrous oxygen tanks, battery powered IV pumps, and ferrous scissors, pens and homostats.
Ancillary equipment that should be included in an MRI department includes which of the following?Non-ferrous wheelchair or stretcher, proper monitoring equipment for sedated pt, a crash cart for emergency situations.
Which of the following ancillary staff should be trained in the safety procedures of the MRI department?Janitorial stall, nursing stall, and MRI dept clerical staff.
RF coils should be looped during scanning to improve signal to noise.True
Which of the following is an important environmental consideration necessary to maintain proper computer and gradient function?Barometric pressure
Metal implants within the body, depending on the location, can pose what type of problems during the MRI exam?Torque, heading, and artifacts
70) Which of the following patients should be absolutely excluded from having an MRI exam?Pt with cornea implants
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Section 8

Question Answer
Biological effects associated with exposure to static magnetic fields below 2 tesla include which of the following?Minimal increase in body temperature
Biological effects associated with exposure to static magnetic fields above 2 tesla include which of the followingFatigue, headaches, and hypotension.
Heating that is directly associated with the RF pulse sequence should not increase the core body temperature greater than:1 degree fahrenheit
To minimize MRI contrast agent's toxicity, the agent should be:Excreted intact by the kidneys, and excreted intact by the gallbladder and intestines.
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