Teenager on an aggressive weight-loss diet who has recently begun vomiting after meals

Upper GI of superior mesenteric artery syndrome
Delayed AP image from an upper GI shows a markedly dilated first and second part of the duodenum to the right of the spine with a marked narrowing and transition in duodenal caliber over the spine and only a small amount of contrast in the third part of the duodenum to the left of the spine. During the exam, marked to and fro peristaltic motion was noted in the first and second parts of the duodenum.

The diagnosis was superior mesenteric artery syndrome.