What about the pancreas?

37 yo M presents with abdominal pain of acute onset. A CT angiogram of the aorta was performed. This showed a normal aorta, but a quite abnormal pancreas with enlargement and adjacent edema, interpreted as acute interstitial edematous pancreatitis.

But is it? On conventional imaging, especially a single phase exam as in this case, diagnosis of pancreatic necrosis can be very difficult. On spectral analysis, there is no uptake of iodine in the pancreatic body and tail. This is therefore necrotic pancreatitis, with its substantially higher morbidity.

Lipase returned at >4000. On HD #3, patient developed abdominal compartment syndrome and was taken to the OR. Multiple subsequent surgeries including necrosectomies confirmed sterile pancreatic necrosis. 

Underdiagnosis of pancreatic necrosis on CT is not uncommon. Spectral CT shines in this situation.

Conventional CT: changes of pancreatitis

Iodine map shows complete absence of uptake in pancreatic body and tail. Even in this early phase of enhancement, there should be some uptake in the pancreas.

Oblique axial image with iodine overlay shows some iodine uptake in the head of pancreas, but none in the body and tail consistent with necrosis.