A large thrombus (blue arrow) is seen filing the right sided branches of the superior mesenteric vein, with a tongue of thrombus extending up almost to the pancreas. The bowel drained by these occluded branches is thick-walled and poorly enhancing (blue dotted line).
Branches draining the more proximal small bowel remain patent (green arrow) and jejunal loops appear to have normal wall thickness (greed dotted line) although enhancement cannot adequately be assessed due to positive luminal contrast.
Some loops of distal ileum have hyperdense walls (yellow dotted line), which would represent enhancement or, more likely in this setting, submucosal red cell extravasation. This is why a non-contrast initial scan is useful.