What is artifact in an MR Image?
Information in the image that is incorrect or misrepresents true anatomy as a result of the imaging process itself
MR image artifacts may occur when?
-When hardware fails
-if software bugs exist.
-When incorrect parameters are selected.
-Directly from the patient
-The MR system needs maintenance
-the appropriate parameters are not selected.
True/False:
MR artifacts can always be corrected, or at least minimized by you, the technologist.
False
What is the most common artifact?
motion
What is an example of physiological image artifact?
- Cardiac motion
-non-correct patient breathing during abdominal imaging
Motion artifact occurs in which direction?
Phase direction
Motion artifacts are caused by:
spins that change location from one phase encoding step to the next.
Pre-saturation RF pulses are:
RF Pulses Placed spatially over specific areas of anatomy to prevent artifacts originating from the anatomy.
The parameter used by a technologist that uses a frequency or slice-encoding multi-lobed graidnet to “rewind” moving spins such as blood or CSF to prevent or reduce flow artifact is:
Gradient moment nulling
Susceptibility artifact can be caused by:
-Metal in the area of interest
-Tissue-air interfaces
-A tissue-compact bone interfaces
One effective method of reducing metal artifacts is to:
increase the receive bandwidth
Good methods for reducing respiratory ghosting artifacts include:
-Breath-hold the patient
-use respiratory navigators
the default frequency encoding direction for an axial of the brain is:
anterior to posterior
“y” direction
Chemical Shift artifacts occur in the _____ direction
Frequency
the most effective way to decrease chemical shift artifact is to increase ________
receive bandwidth
Chemical Shift Artifacts _________ as field strength increases.
increase
Truncation/Gibbs artifacts appear as a “____________” appearance
ringing
Trunctation/Gibbs can be reduced by:
increasing phase and frequency encoding steps
