Detecting vascular encasement

Examples of a contrast enhanced CT angiography demonstrating different degrees of vascular encasement by a pancreatic adenocarcinoma; axial images.
(A) Adenocarcinoma of the head of the pancreas with <25 percent of involvement of the superior mesenteric vein (SMV) circumference.
(B) Adenocarcinoma of the head pancreas which is contacting 50 percent of the circumference of the SMV.
(C) Adenocarcinoma of the uncinate process of the pancreas involving >75 percent of the circumference of the SMV as well as narrowing of its lumen.
(D) Adenocarcinoma of the body of the pancreas extending superiorly and encasing the celiac trunk (V-shaped structure containing contrast).