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| Audio Frequency Artifact |   |
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Quick Overview
DESCRIPTION
Ghosting, lines or spots
REASON
Wrong modulation at audio rate, wrong audio signal
HELP
AC-line synchronization
Two types of audio-frequency problems are possible:
1. Modulation of the MR signal at an audio rate
2. Audio signal component at digitizer input
Problem 1 looks like ghosts, weak copies of the real image, displaced along the phase encoding direction. The number and intensity of the ghosts depends upon the relationship between the period of the audio modulation and the repetition time.
Problem 2 shows up as lines or spots at the appropriate points along the frequency direction. If there is no correlation between the audio period and TR, lines are generated or discrete spots occur.
Image Guidance
Both problems can be lessened by use of AC-line synchronization (line trigger). | |
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