RESUMO
The process of creating MR images frequently gives rise to artifacts in the final display. Many artifacts may be corrected or ameliorated through an understanding of their cause. This requires familiarity with scanner design; theory of operation; and image acquisition, generation, and display. Some artifacts are obvious, totally degrading the image; others are regional, leaving much of the scan undisturbed. In some cases, the degradation is permanent; in others, the data can be reprocessed or manipulated to yield artifact-free images. Some artifacts are overt and easily identified. Others, such as those caused by phase-shift or gradient-strength effects, are subtle and require careful observation for detection.
Assuntos
Espectroscopia de Ressonância Magnética , Erros de Diagnóstico , Eletricidade , Humanos , Espectroscopia de Ressonância Magnética/instrumentação , Movimento , Controle de Qualidade , SoftwareRESUMO
Cosmetics can produce severe distortion of the orbital contents in MR imaging. This distortion, typical of compounds that exhibit a permanent magnetic moment, results from iron oxide in the pigments used to produce dark shades of makeup. In general, the artifact created by cosmetics does not interfere with interpreting routine head scans. However, if the orbital contents are the subject of clinical concern, the images may then be rendered nondiagnostic. The artifact created by the makeup is propagated along the frequency-encoding axis of the images.