Artifacts

Magnetic resonance imaging (MRI) uses ________ separate magnetic fields to perform the task of routine image acquisition.

three

All of the following are potential risk factors for SAR thermal absorption during an MR pulse sequence EXCEPT:

Elderly population

Hypotension

Obesity

Diabetes

Hypotension (Cardiovascular disease, obesity, elderly population, diabetics and hypertensive patients are all at risk for increased SAR thermal absorption)

Motion is seen as a smearing across the image in the:

Phase encoding direction

________ occurs when tissue outside the Field of View is undersampled, causing a misregistration of anatomical location, in the phase direction, but on the opposite side of the anatomical location, also known as wrap-around artifact.

Aliasing artifact

Letter A in Image 101 is pointing to what type of MR artifact?

chemical shift

Image 86 is an example of which kind of artifact?

Magnetic susceptibility

One can correct for the artifact seen in Image 100 by:

Acquiring stacks as complete packages, Increasing interslice gap, Interleaved slice order

Aliasing occurs because tissue outside the selected FOV is:

undersampled

Magnetic susceptibility artifacts are more prominent with:

Gradient echo

A decrease in the voxel volume yields:

A decrease in partial volume averaging

The yellow arrows in Image 201 display what type of MRI artifact?

Dielectric effects

Image 87 displays what kind of artifact?

Motion/ghosting in the phase direction

______________ are caused by local eddy currents due to the increased conductivity of body tissue, and are identified by areas of shading or signal loss

Dielectric effects

To minimize cross talk artifact,

Increase the interslice gap

What is the term used to measure the magnetic field strength in the periphery of the MRI scan room

Gauss (Tesla measures magnetic filed strength in isocenter)

Primarily stemming from active RF coil channels or elements outside the scanning field of view, ______________ artifacts can be corrected by simply de-selecting the element(s) outside the scanning range.

Annefact

The ________ should be _______ to reduce chemical shift artifacts.

reciver bandwidth; increased

The red arrows in Image 172 are indicative of which type of MRI artifact?

Parallel Imaging