Protocol error artifacts in MRI: Sources and remedies revisited

Abstract 

Purpose

The objective of this article is to review the sources, effects and remedies of the artifacts that are controlled by operator variable parameters. Protocol error artifacts include susceptibility, ferromagnetic, truncation, aliasing, chemical shift, black boundary, cross-talk, partial volume averaging, and saturation artifacts. All these artifacts are simulated/developed in-house along with a few uncommonly seen artifacts. Also, the effectiveness of various remedial measures for all these artifacts has been demonstrated.

Results

Susceptibility, ferromagnetic, and black boundary artifacts can be reduced by using spin echo (SE) pulse sequence. Susceptibility and ferromagnetic artifacts are minimized by altering time-to-echo (TE), though chemical shift artifact (CSA) may turn into black boundary artifact and vice versa when TE is varied. By employing three-dimensional (3D) volume acquisitions susceptibility, ferromagnetic and partial volume averaging (PVA) artifacts can be reduced. Field of view (FOV) has an effect on aliasing, CSA and PVA artifacts, whereas by proper selection of phase encoding and frequency-encoding axes, susceptibility, ferromagnetic, aliasing and CSA can be overcome.

Conclusions

These artifacts can usually be ameliorated or avoided by altering parameters that are under operator control and employing remedial measures, thus maintaining good image quality and avoiding diagnostic errors, thereby enhancing the usefulness of MRI in clinical practice.

Keywords: Artifact, Magnetic Resonance Imaging (MRI), Remedies