History: intermittent abdominal pain
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As you can see there is abrupt narrowing and upward curving of the proximal celiac trunk.
Answer: Celiac artery compression syndrome (aka median arcuate ligament syndrome). - essentially a low inserting median arcuate ligament (connects the L and R diaphragmatic crura) which compresses the celiax trunk, especially with gastric distention (post-prandial)
Remember this can be a NORMAL findings especially with expiratory imaging. So you need a good history to correlate with (In this case they actually called looking for it!)
Detailed Ref: http://pubs.rsna.org/doi/full/10.1148/rg.255055001