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Common Artifacts in MRI
Vinai Roopchansingh
Functional MRI Facility, National Institute of Mental Health, National Institutes of Health,
Bethesda, MD, USA
June 19, 2015
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 1 / 30
Outline
1 Hardware artifacts, i.e. B0, B1, etc.
2 Reconstruction artifacts
3 Patient/sample artifacts
4 Misc. / grab-bag
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 2 / 30
Outline
1 Hardware artifacts, i.e. B0, B1, etc.
2 Reconstruction artifacts
3 Patient/sample artifacts
4 Misc. / grab-bag
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 3 / 30
Hardware imperfections
Distortions usually come from B0 or gradient issues.
Image shading/intensity problems usually come from B1 issues.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 4 / 30
Hardware imperfections
Distortions usually come from B0 or gradient issues.
Image shading/intensity problems usually come from B1 issues.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 4 / 30
Hardware imperfections
Distortions usually come from B0 or gradient issues.
Image shading/intensity problems usually come from B1 issues.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 4 / 30
Distortion issues
Larmor equation ⇒
ω0 = γB0
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 5 / 30
Distortion issues
Larmor equation ⇒
ω0 = γB0
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 5 / 30
Distortion issues
Larmor equation ⇒
ω0 = γB0
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 5 / 30
Geometric distortion - Extreme example
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 6 / 30
Geometric distortion - Extreme example
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 6 / 30
Geometric distortion - Extreme example
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 6 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
More common, less extreme, distortion examples
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 7 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Even more subtle distortion issues
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 8 / 30
Very exotic, very troublesome, distortion issue
Data provided by J. Sarlls
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 9 / 30
Very exotic, very troublesome, distortion issue
Data provided by J. Sarlls
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 9 / 30
Very exotic, very troublesome, distortion issue
Data provided by J. Sarlls
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 9 / 30
Very exotic, very troublesome, distortion issue
Data provided by J. Sarlls
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 9 / 30
Very exotic, very troublesome, distortion issue
Data provided by J. Sarlls
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 9 / 30
Issues with image intensity, shading, noise
Problems with image intensity variation, noise, etc
⇒ problems along the RF chain
⇒ limitations imposed by physics (geometry, sensitivity).
e.g. RF Coils, RF amplifiers, etc.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 10 / 30
Issues with image intensity, shading, noise
Problems with image intensity variation, noise, etc
⇒ problems along the RF chain
⇒ limitations imposed by physics (geometry, sensitivity).
e.g. RF Coils, RF amplifiers, etc.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 10 / 30
Issues with image intensity, shading, noise
Problems with image intensity variation, noise, etc
⇒ problems along the RF chain
⇒ limitations imposed by physics (geometry, sensitivity).
e.g. RF Coils, RF amplifiers, etc.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 10 / 30
Issues with image intensity, shading, noise
Problems with image intensity variation, noise, etc
⇒ problems along the RF chain
⇒ limitations imposed by physics (geometry, sensitivity).
e.g. RF Coils, RF amplifiers, etc.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 10 / 30
Failing hardware - single-channel coil
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 11 / 30
Failing hardware - single-channel coil
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 11 / 30
Failing hardware - single-channel coil
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 11 / 30
Failing hardware - multi-channel array coils
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 12 / 30
Failing hardware - multi-channel array coils
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 12 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Coil Sensitivity
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 13 / 30
Dielectric Effects / a.k.a. B1 Inhomogeneities
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 14 / 30
Dielectric Effects / a.k.a. B1 Inhomogeneities
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 14 / 30
Dielectric Effects / a.k.a. B1 Inhomogeneities
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 14 / 30
Outline
1 Hardware artifacts, i.e. B0, B1, etc.
2 Reconstruction artifacts
3 Patient/sample artifacts
4 Misc. / grab-bag
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 15 / 30
Accelerated Reconstruction artifacts
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 16 / 30
Accelerated Reconstruction artifacts
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 16 / 30
Accelerated Reconstruction artifacts
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 16 / 30
Accelerated Reconstruction artifacts
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 16 / 30
Accelerated Reconstruction artifacts
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 16 / 30
Error combining data
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 17 / 30
Error combining data
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 17 / 30
Error combining data
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 17 / 30
Outline
1 Hardware artifacts, i.e. B0, B1, etc.
2 Reconstruction artifacts
3 Patient/sample artifacts
4 Misc. / grab-bag
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 18 / 30
Patient/sample artifacts
Probably hardest class of artifacts to deal with.
Ethical responsibility toward your patients, volunteers,
and animals.
Experimental validity - not supposed to change the
state of the thing you are measuring.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 19 / 30
Patient/sample artifacts
Probably hardest class of artifacts to deal with.
Ethical responsibility toward your patients, volunteers,
and animals.
Experimental validity - not supposed to change the
state of the thing you are measuring.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 19 / 30
Patient/sample artifacts
Probably hardest class of artifacts to deal with.
Ethical responsibility toward your patients, volunteers,
and animals.
Experimental validity - not supposed to change the
state of the thing you are measuring.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 19 / 30
Patient/sample artifacts
Probably hardest class of artifacts to deal with.
Ethical responsibility toward your patients, volunteers,
and animals.
Experimental validity - not supposed to change the
state of the thing you are measuring.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 19 / 30
B0 uniformity
Basic premise of MRI - VERY uniform magnetic field,
distorted in a controlled fashion to provide spatial
information.
⇒ Have to revise this assumption when imaging.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 20 / 30
B0 uniformity
Basic premise of MRI - VERY uniform magnetic field,
distorted in a controlled fashion to provide spatial
information.
⇒ Have to revise this assumption when imaging.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 20 / 30
B0 uniformity
Basic premise of MRI - VERY uniform magnetic field,
distorted in a controlled fashion to provide spatial
information.
⇒ Have to revise this assumption when imaging.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 20 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
B0 uniformity in the human brain
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 21 / 30
Different tissue types, namely fat
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 22 / 30
Different tissue types, namely fat
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 22 / 30
Different tissue types, namely fat
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 22 / 30
Physiology
van Gelderen: Magnetic Resonance In Medicine (57:2), 362-368, Feb 2007.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 23 / 30
Physiology
van Gelderen: Magnetic Resonance In Medicine (57:2), 362-368, Feb 2007.
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 23 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Motion
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 24 / 30
Outline
1 Hardware artifacts, i.e. B0, B1, etc.
2 Reconstruction artifacts
3 Patient/sample artifacts
4 Misc. / grab-bag
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 25 / 30
EPI Nyquist Ghosting
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 26 / 30
EPI Nyquist Ghosting
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 26 / 30
EPI Nyquist Ghosting
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 26 / 30
Saturation effects
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 27 / 30
Saturation effects
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 27 / 30
Saturation effects
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 27 / 30
Saturation effects
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 27 / 30
Saturation effects
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 27 / 30
Pop-quiz
How to differentiate fat shift artifact from Nyquist ghost shift ?
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 28 / 30
Pop-quiz
How to differentiate fat shift artifact from Nyquist ghost shift ?
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 28 / 30
Pop-quiz
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 29 / 30
Acknowledgments
J. Sarlls (NMRF-NINDS)
R. M. Birn (MCW/FIM-NIMH/UW)
S. Wei and S. Kippenhan (SIN-NIMH)
J. Gonzalez-Castillo (FIM-NIMH)
D. Handwerker (FIM-NIMH)
Vinai R. (FMRIF/NIMH/NIH/DHHS) MR Artifacts 2015.06.19 30 / 30
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