Vascular Involvement

Identification of pathways of tumor spread is important for surgical planning in order to achieve a margin-negative resection, particularly when the tumor spreads beyond the usual extent of pancreaticoduodenectomy or when the tumor is located in the retroperitoneum behind the SMA where direct intraoperative assessment is not possible until the final stage of resection (Figs. 127 and 12-8). However, tumors arising from the pancreas adjacent to the duodenum tend to infiltrate along the anterior SPDA toward the gastroduodenal artery behind the pylorus (Fig. 12-9) and the proper hepatic artery in the hepatoduodenal ligament or along the posterior SPDV toward the inferior surface of the portal vein. Tumors arising in the cranial portion of the pancreatic head near the neck may infiltrate superiorly toward the CHA (Fig. 12-10) or infiltrate inferiorly into the mesentery and transverse mesocolon and along the SMV. Tumors arising from the uncinate process may infiltrate along the IPDA or IPDV toward the posterior surface of the SMA (Fig. 12-8) or into the jejunal mesentery where the IPDA originates from. Tumors arising from the head of the pancreas near the confluence of the gastrocolic trunk where it drains into the SMV may infiltrate into the base of the transverse mesocolon along the middle colic artery or vein (Fig. 12-6). Knowledge of this anatomy and of the potential pathways of local tumor invasion is important for surgical planning when an aggressive surgical approach is planned.

We defined CT criteria of vascular involvement and used these criteria to assess vascular involvement in 56 patients with pancreatic ductal adenocarcinoma who underwent surgical exploration.18,19 When there was a fat plane (type A) or normal pancreatic parenchyma (type B) separating the tumor from adjacent vessels, the tumor was resected without venous resection in 21 of 22 patients (95%). When the tumor was inseparable from the vessels but the points of contact formed a convexity against the vessel (type C), it was not reliable to predict whether the tumor was fixed against the vessel (Fig. 12-11). When the tumor was partially encircling (type D), the tumor was fixed against the vessels in most cases (Figs. 12-8 and 12-12). The resectable rate was 47%, but resection also required venous resection. When the tumor was completely encircling (type E) or

Resectable Pdac Uncinate Process

Fig. 12—8. Tumor (T) involving the uncinate process.

Note hypodense tumor infiltrate along the inferior pancreaticoduodenal artery (small arrow) behind the superior mesenteric artery (large arrow). This lesion is not resectable.

Fig. 12—7. Tumor (T) involving the head of the pancreas.

Note tumor infiltrate (t) along the superior mesenteric artery (arrow). It is not possible to distinguish perivascular or perineural invasion in this case because the nerve plexus also accompanies the artery. The lesion is not resectable.

Fig. 12—8. Tumor (T) involving the uncinate process.

Note hypodense tumor infiltrate along the inferior pancreaticoduodenal artery (small arrow) behind the superior mesenteric artery (large arrow). This lesion is not resectable.

Fig. 12—9. Tumor in cephalad portion of head of pancreas.

Tumor (T) involves the gastroduodenal artery (large arrow) and the replaced right hepatic artery (small arrows) from the SMA.

Fig. 12-10. Tumor (T) at neck of pancreas with direct involvement of the common hepatic artery (arrow).

Fig. 12-10. Tumor (T) at neck of pancreas with direct involvement of the common hepatic artery (arrow).

Vascular Dynamic

Fig. 12-11. Ductal adenocarcinoma of head of pancreas.

Medial extension of tumor (small arrow) just abuts the SMA (large arrow), a type C vascular involvement. Patient did not undergo resection because meta-static disease in liver was found on follow-up study.

Fig. 12-11. Ductal adenocarcinoma of head of pancreas.

Medial extension of tumor (small arrow) just abuts the SMA (large arrow), a type C vascular involvement. Patient did not undergo resection because meta-static disease in liver was found on follow-up study.

occluding (type F) the vessel, all tumors were not resectable with a negative margin. We believe that these improved results are largely due to scanning with thin sections during the bolus phase of intravenous contrast enhancement, when the lesion and its extent along the vessels are easier to identify.

With our scanning technique described earlier, we have shown that CT accurately defines the extent of vascular involvement and correctly predicts resectability in 88% of patients.

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