Parallel imaging artifacts in MRI (ASSET, SENSE, GRAPPA)
Noise bands or a ghost in the centre of the image after turning acceleration up. This is what went wrong.
Parallel imaging artifacts
A faint folded ghost in the centre of the image, or a band of grainy noise through the middle.
Acceleration factor too high for the coil geometry; FOV smaller than the anatomy with SENSE-type reconstruction; or the calibration scan no longer matches the patient position (motion or breath-hold mismatch).
- Lower the acceleration factor
- Enlarge the FOV to include all anatomy in the phase direction
- Repeat the calibration scan in the same breath-hold position
- Use autocalibrating methods (ARC / GRAPPA) when wrap is unavoidable
Less acceleration means longer scans or longer breath-holds.
This page is one entry from the MRI Technologist Reference
The full reference has 31 protocols, 9 dynamic study timelines, 19 artifacts, 16 scanner problems and 15 safety topics, as a PDF in English and Arabic plus an interactive tool.
Educational reference. It does not replace your site protocols, the radiologist's instructions, the MR safety officer, or the manufacturer's instructions for any implant, device or contrast agent. Parameter values are typical starting points at 1.5 T and must be adapted to the scanner, coil and patient.