Figure 5a. Acute mesenteric ischemia in a 59-year-old man who was admitted to the hospital with atrial fibrillation and acute abdominal pain. (a) Coronal 3D multi-detector row CT scan demonstrates segmental thickening of a small bowel loop in the left side of the abdomen (straight arrow). This loop is narrowed compared with the remainder of the small bowel, which is minimally dilated. The small mesenteric vessels feeding the loop are distended (curved arrows). (b) Coronal 3D multi-detector row CT scan obtained 4 days later demonstrates pneumatosis of the small bowel loop (arrow), a finding that is compatible with infarction. Note that the dilated mesenteric vessels are no longer visible.