• Like
  • Save
Artifacts in MRI
Upcoming SlideShare
Loading in...5
×
 

Artifacts in MRI

on

  • 26,421 views

A short list of mri artifacts

A short list of mri artifacts

Statistics

Views

Total Views
26,421
Views on SlideShare
26,028
Embed Views
393

Actions

Likes
15
Downloads
2
Comments
4

16 Embeds 393

http://www.imagemmedica.com 158
http://imagemmedica.blogspot.com.br 116
http://www.slideshare.net 46
http://arunsradiology.blogspot.com 28
http://imagemmedica.blogspot.pt 10
http://www.slashdocs.com 7
https://clickup.up.ac.za 7
http://www.arunsradiology.blogspot.com 6
http://myradiologyworld.blogspot.com 3
http://myradiologyworld.blogspot.in 3
http://www.imagemmedica.blogspot.com.br 3
http://feeds.feedburner.com 2
http://myradiologyworld.blogspot.ch 1
http://webcache.googleusercontent.com 1
http://www.myradiologyworld.blogspot.com 1
http://imagemmedica.blogspot.se 1
More...

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel

14 of 4 Post a comment

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

    Artifacts in MRI Artifacts in MRI Presentation Transcript

    • Artifacts in MRI BY Arun A Dr.Shaji’s MRI Perinthalmanna
    • Common Artifacts
      • Wrap around
      • Partial volume
      • Chemical shift mis registration
      • Chemical shift edge cancellation
      • Truncation
      • Motion induced ghost
      • Zipper
      • Corduroy appearance
      • Susceptibility
      • Cross excitation
      • Sub optimal fat saturation
      • Magic angle
      • Eddy current
      • Others
    • WRAPAROUND
      • CAUSE
      • FOV too small for body part
      • CORRECTION
      • Sample data sufficient for a larger FOV
      • Use of local coil to reduce sensitivity of tissue outside image
      APPEARANCE Body parts extends beyond one edge of image and is projected at the opposite side Show Images
    • PARTIAL VOLUME
      • CAUSE
      • More than one tissue is included with in a voxel
      • Usually because of thick slices
      • CORRECTION
      • Increase spatial resolution (particularly in the slice direction )
      • APPEARANCE
      • Edge of structure contain tissues from two adjacent slices
      Show Images
    • CHEMICAL SHIFT MISREGISTRATION
      • CAUSE
      • Water and fat are misregistered relative to each other
      • CORRECTION
      • Increase sampling Bandwidth per pixel
      • APPEARANCE
      • Bright band on one slice dark band on other side of water structure surrounded fat along the frequency- encoded axis
      Show Images
    • CHEMICAL SHIFT EDGE CANCELLATION
      • CAUSE
      • Water and lipid signals in a voxel at fat – water interfaces destructively
      • CORRECTION
      • Use spin echo or In phase gradient echo technique
      • Suppress lipid signal intensity
      • APPEARANCE
      • Black line at fat–water interfaces
      Show Images
    • TRUNCATION
      • CAUSE
      • Abrupt ,high contrast boundaries cannot be accurately represented by Fourier Transform
      • CORRECTION
      • Increase spatial resolution
      • APPEARANCE
      • Ring –down artifact at high contrast interfaces
      Show Images
    • MOTION INDUCED GHOST
      • CAUSE
      • Motion causes phases changes during signal sampling
      • Or intensity changes b/w signals Both result in phase encoding errors
      • CORRECTION
      • Average multiple signals
      • Complete image acquisition rapidly
      • Trigger acquisitions so the image anatomy is constant from view to view
      • Balance gradients to eliminate gradient moment
      • Reduce signal of moving tissue
      • APPEARANCE
      • Repetitive patterned noise that resembles the source structure
      • Repeated at regular intervals along phase encoding axis
      Show Images
    • ZIPPER
      • CAUSE
      • Nondecayed transverse magnetization
      • RF feed through
      • Or extraneous noise
      • CORRECTION
      • Improve spoiling of transverse magnetization
      • Alternate polarity of excitation pulses
      • Eliminate source of noise
      • APPEARANCE
      • Band of alternative white and black dots
      Show Images
    • CORDUROY APPEARANCE
      • CAUSE
      • Bad data points
      • CORRECTION
      • Increase sapling of k-space
      • APPEARANCE
      • Corduroy appearance across some images
    • SUSCEPTIBILITY
      • CAUSE
      • Magnetic field altered by heterogeneous magnetic properties in body part
      • CORRECTION
      • Eliminate source of heterogeneous susceptibility
      • Maximize sampling bandwidth
      • Minimize TE
      • Refocus echoes
      • APPEARANCE
      • Signal loss
      • Distortion
      Show Images
    • CROSS EXITATION
      • CAUSE
      • RF pulse targeted to one slice particularly excites an adjacent slice
      • CORRECTION
      • Use gap b/t slices in 2D multislice acquisitions
      • Allow sufficient time for recovery b/w radial overlapping slice acquisitions
      • APPEARANCE
      • Reduced signal intensity
    • SUBOPTIMAL FAT SATURATION
      • CAUSE
      • Magnetic field heterogeneity causes the lipid resonance to vary within the field of view so the fat suppression RF pulse doesn't correspond to all lipid
      • CORRECTION
      • Improve magnetic field shimming
      • Improve tuning of fat suppression pulse
      • APPEARANCE
      • increased signal intensity on lipid
      • Possibly suppression of water signal
    • MAGIC ANGLE
      • CAUSE
      • T2 of oriented fibers depends on angle relative to magnetic field
      • CORRECTION
      • Use sufficiently long TE for structure to have long signal intensity regardless of angle
      • APPEARANCE
      • variable signal intensity on of tendons and other structures
      Show Images
    • EDDY CURRENT
      • CAUSE
      • Electrical currents caused by rapidly switching gradients
      • CORRECTION
      • Improve precision of gradient pulses
      • Use eddy current compensation
      • APPEARANCE
      • Reduced peripheral signal intensity
      Show Images
    • OTHERS
      • In homogeneity on fat sat
      • Annefect
      • Gradient amplifier failure
      • Spike noise
      • Spatial saturation
      • Out of slice contamination
    • Wrap around NEXT IMAGE
    • wraparound
    • Partial volume 3 mm Partial volume 3 mm 10 mm A partial volume artifact is any artifact which is caused by the size of the image voxel.
    • Chemicals shift NEXT IMAGE
    • Chemicals shift
    • Motion NEXT IMAGE
    • Motion
    • Metal object/susceptibility NEXT IMAGE
    • Metal object/susceptibility
    • Eddy current Metal object/susceptibility
    • ZIPPER NEXT IMAGE
    • ZIPPER
    • Truncation NEXT IMAGE
    • Truncation Truncation
    • Magic Angle Truncation
    • In homogeneity on fat sat NEXT IMAGE Truncation
    • Annefect NEXT IMAGE
    • Gradient amplifier failure NEXT IMAGE
    • Spike noise NEXT IMAGE Annefect
    • Spike noise NEXT IMAGE Annefect
    • Spatial saturation NEXT IMAGE Annefect
    • Out of slice contamination