| reverberation | Multiple echoes or reflections; in ultrasonography, an artifactual image caused by delay of an echo which has been reflected back and forward again before returning to the transducer. (05 Mar 2000) |
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| artifact | Something artificial, a distortion that does not reflect normal anatomy or pathology, not usually found in the body. For example: in radiology, the appearance on an X-ray of a surgical metal clip that obscures the clear view of an anatomical structure. (16 Dec 1997) |
| chemical shift artifact | In magnetic resonance imaging, a dark band caused by a biochemical difference in resonant frequency of adjacent regions rather than a true anatomic separation. (05 Mar 2000) |