Table 6.

Grading system proposed by Raptopoulos et al. [23] for predicting vascular invasion by tumor

Category	Description	Comment
Grade 0	Normal, with a fat plane or normal pancreas between the tumor and the vessel	100% resectable
Grade 1	Loss of fat plane between the tumor and the vessel, with or without smooth displacement of the vessel	100% resectable
Grade 2	Flattening or slight irregularity of one side of the vessel	92% resectable
Grade 3	Encased vessel with tumor extending around at least two sides (two-thirds of the perimeter), altering its contour and producing concentric or eccentric narrowing of the lumena	The recommended threshold for predicting vascular invasion. In this study, resection was performed in 1 of 10 patients with grade 3 findings, but tumor along perivascular neural bundles was present at resection margins.
Grade 4	Occluded vessel	No attempted surgery

^aIn a recent article by the same group, encasement was defined as tumor extending around 50% of the perimeter of a vessel [24]