Artifacts

Ribbons of signal

• Select your coil on the Coils tab.
• Confirm that the selected coil closely matches the FOV prescription.
• Turn on the Annefact suppression User CV.
• Annefact is prevalent in spine imaging. When you scan a spine:
  • Use Freq S-I. (This may increase motion artifacts.)
  • Put SAT bands anterior to the spine.

Anatomy aliases back into center of image

• Cover the entire FOV ( No Phase FOV less than 1).
• Reduce the ASSET factor.
• Remove ASSET.
• Repeat the calibration scan.

Smearing in image

• To avoid gross motion, use immo-bilization techniques, such as straps, sandbags, or pillows.
• To avoid respiratory or cardiac motion, try the following techniques:
  • Increase NEX.
  • Use PROPELLER or PROMO sequences.
  • Use respiratory gating, such as Respiratory Triggering or Navigator.

Poor chemical fat sat uniformity

• Position the patient’s neck as paral-lel as possible to the long axis of the magnet.
• In fat sat sequences, utilize shim volumes.
• Instead of a fat sat sequence, use a STIR or Flex.

Mottled appearance in anatomy

Boundaries between fat and water are either bright or dark

• Out of Phase: 2.2
• In Phase: 4.4
• Out of Phase: 6.6

Inhomogeneity/Shading in the image

• Use intensity correction, such as PURE.
• Use dielectric pads to smooth inho-mogeneities in any sequence.

Ring-like artifact

• Position an angled anterior SAT band to suppress the orbit signal.
• Use Nyquist reduction, CV12, to reduce ghosting caused by hardware delays and Eddy currents.
• If available, use HyperBand to reduce pileup from the orbits.

Areas that should appear fat suppressed are water suppressed, and ar-eas that should appear water suppressed are fat suppressed

This error may occur in regions of high magnetic field variation, in spatially isolated tissue, and/or in images with low signal-to-noise ratios, due to:

• patient or tissue motion
• phase wrap artifacts

• LAVA Flex utilizes high bandwidth to minimize chemical shift effect.
• Due to chemical shift challenges, use the following recommended TE values. These TE limits will limit the maximum resolution (frequency encodings) you can choose:
  • TE = 2 to 2.5 ms(out-of-phase)
  • TE2 = 4 to 5.3 ms (in-phase)
• Decrease FOV.
• Increase NPW factor.
• To offset the time increase in these instances:
  • Reduce your phase matrix.
  • Increase acceleration.
  • Increase slice thickness and reduce the number of slices.

Appears as small, wavy lines throughout the image

• Use an even NEX.
• Turn on the Enhanced Fine Line Suppression User CV.

Signal void, image distortion

• Reduce susceptibility with one of the folllowing techniques:
  • Instead of GRE, use FSE sequence with increased ETL.
  • Use STIR for fat suppression.
  • Increase BW.
  • Obtain thin slices.
  • Increase the matrix.
• If available, use MAVRIC-SL or Hyper-MAVRIC to reduce metal artifacts.

Bright areas closer to the surface of patient’s body where the coil is

• Use the available intensity-correction techniques, such as PURE.
• Put padding between the coil and the patient.
• Do not wrap flexible coils excessively tight.

Slight signal voids, most commonly in superior slices

• Increase ETL, avoid patient motion, and increase FOV to include all intended anatomy.
• Use No Phase Wrap.

Noise in image background

Blurred images

Black holes in DWI PROPELLER images

Rippling in images

• Increase the FOV and/or reposition the slice prescription.
• If available, use No Phase Wrap or Flexible No Phase Wrap.

Zipper artifact criss-crossing in image

Noise in image appearing as streaks, most prevalent in the background

• Use No Phase Wrap, or increase Flexible No Phase Wrap Factor.
• Increase FOV.
• Apply PURE.

Intensity variations across an image

• Ensure that there is no metal on or in the patient.
• If you suspect a faulty coil element, con-tact your service representative.

Corduroy effect across image, or one solid line through image

Area of reduced signal intensity or bands of signal cancellation

• Put the anatomy of interest in the center of the magnetic field, in the center of the coil.
• Use STIR or 2D FLEX for the T2 fat sat sequence.
• Use 3D Vibrant Flex instead of Vibrant with ASPIR or Special.
• Use proper shim or dual shim volume placement on any fat sat sequence.

Appears as reduced signal intensity

• Use ASPIR instead of conventional fat saturation.
• Ensure that the patient does not come in direct contact with the coils. Put a pad between the patient and the coil.

Slight streak artifact through portions of the image

• Change the scan plane.
• Increase the NEX value or the FOV coverage.

Bright spot close to the center of the image

• If your system does not have AIR Touch, ensure that the coil coverage matches the FOV in the prescription.
• Use No Phase Wrap.
• Do not swap phase and frequency.

Appears around bright tissue, enhanced if the brightness changes sharply

• Reduce FOV.
• Increase matrix.
• Change the TE value to MinFull if Minimum is used.
• If available, use AIR Recon DL.

Signal voids in a DWI or EPI image

• Use a lower b-value.
• In the Details tab, select Zero Filling instead of Homodyne.

Image fold onto the opposing side of anatomy

• To minimize time increases, use a fractional amount of phase wrap or Flexible No Phase Wrap.
• Increase your FOV to include all anatomy.