What are the possible diagnoses in this patient?
Infective colitis is the most likely cause, however inflammatory processes can have a similar picture. Ischaemic colitis should also be considered however since the majority of the bowel is involved, crossing vascular territories, this is less likely. Neutropaenic and radiation-associated colitis are also other causes.
What other sign would usually be more prominent in acute colitis?
Bowel wall thickening is commonly seen, however this patient had a long period of infection and subsequent antibiotic therapy so the acute inflammatory changes may have passed.
Why would the arterial system still be enhancing during the porto-venous phase scan (taken around 65-75 seconds)?
Poor cardiac output can make the transit of contrast sluggish and many have contributed in this situation.
Oral contrast also administered.
Bowel wall oedema with enhancement, featureless sigmoid colon and free fluid in keeping with pancolitis. Concertina sign in transverse colon. Fluid filled enhancing small bowel loops.
No pneumoperitoneum. Upper abdominal viscera unremarkable.
Calcified abdominal aorta but major branches patent.
Small bibasal pleural effusions with atelectasis.