The teardrop superior mesenteric vein sign is one of the important signs of unresectability of adenocarcinoma of the pancreatic head.

The sign refers to the tethered, teardrop appearance of the SMV when encased by pancreatic head carcinoma, which renders the tumour unresectable.

The sign is highly specific (98 %) for unresectability, with a positive predictive value of 95 %.

Transient hepatic attenuation difference (THAD) stands for a perfusional liver parenchymal change detected only on the arterial phase of a bolus-enhanced dynamic CT examination that returns to normal on portal venous phase.