Fluid-level motion artifact in computed tomography

Ingestion of oral contrast material as a routine part of abdominal computerized tomographic scanning creates numerous gas and fluid interfaces within the gastrointestinal tract. Following deep inspiration or expiration, fluid motion induced by shifting intra-abdominal contents persists for several seconds. This causes radial streak artifacts to arise from air-fluid interfaces, even though respiration is suspended while the scan is made. Such artifacts can be reduced if the beginning of a scan is delayed to allow fluid motion to stop. An alternative is to re-scan an area of interest in the lateral decubitus position so as to shift air-fluid levels and their associated artifacts away from any region in question.