CT criteria for venous invasion in patients with pancreatic head carcinoma

The purpose of the study was to evaluate CT criteria for venous invasion in patients with potentially resectable carcinoma of the pancreatic head, wit h surgical and histopathological correlation. In 113 patients evaluated wit h spiral CT for suspected pancreatic head carcinoma, several CT criteria fo r venous invasion were scored prospectively for the portal vein (PV) and th e superior mesenteric vein (SMV): length of tumour contact with PV/SMV (0 m m, <5 mm, >5 mm); circumferential involvement of the vein (0 degrees, 0-90 degrees, 90-180 degrees, >180 degrees); degree of stenosis; irregularity of the vessel margin; and tumour convexity towards vessel. 65 patients underw ent surgery. Pancreatic head carcinoma was proven and pathology of the vasc ular margin was obtained in 50 of these patients. CT findings for single an d combined criteria were correlated with pathology in these 50 patients, 30 of whom showed venous ingrowth. Invasion was found in all cases with SMV n arrowing (n=7), PV contour involvement>90 degrees (n=6), PV narrowing (n=5) and PV wall irregularity (n=3). The vascular ingrowth rate was 88% (15/17) for tumour concavity towards the PV or SMV. Poor predictors of ingrowth we re length of tumour contact with PV>5 mm (78% ingrowth, 14/18) and contour involvement of the SMV>90 degrees (83% ingrowth, 10/ 12). Absence of vascul ar ingrowth could not be predicted in 100%. In conclusion, CT criteria can predict a high risk of invasion in potentially resectable tumours. Narrowin g of the SMV and the PV seems the most reliable criterion, as well as circu mferential involvement of the PV,90 degrees. The best combination of criter ia was tumour concavity with circumferential involvement>90 degrees (sensit ivity 60% and positive predictive value 90%).