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MRI: chemical shift artifact
light & dark bands at water/fat interphase d/t difference in Lamour Freq - usually in frequency encoding direction
MRI barrel distortion
Image distortion caused by gradient nonlinearities (the peripheral FOV has a tendency of lower field strength, esp with bigger FOV) causing compression of the anatomy
MRI: center-point artifact
a bright spot in the center of the image for imbalanced amplifiers (from RF quadrature coils - coils that simultaneously measured the signal from orthogonal views, have 2 separate amplifiers and gain controls to compensate for signal dropoff.)
MRI herringbone artifacts
caused by braodband RF noise disrupt the image over a much larger area than zipper artifact. Reduce w proper site planning and FT shielding (i.e. a Faraday cage)
MRI Ringing artifacts/ Gibbs phenomenon/ truncation artifacts
near sharp boundaries/ high contrast transitions, appear as multiple regularly spaced parallel bands; more conspicuous with low frequency.
MRI: wraparound artifacts [AKA aliasing]
- mismapping of anatomy lies outside of the FOV of a gradient (with sampling rate less than twice the maximal frequency in the object) => high freq assigned to a lower frequency value.
- Reduce in freq encode direction: low pass filter
- Reduce in phase encode direction: increase number of phase encode steps.
MRI: partial volume artifacts.
heterogeneous signal in a voxel => loss of detail and spatial resolution.
MRI: Motion ghosts
low intensity "ghosts" in the phase encoding direction d/t motion.
MRI: cross talk ghosts
faint images of bright structures outside of the slice.
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