Table 6.

Extramural vascular invasion scoring system by Smith et al. [59]

Score 1	Tumor extension through the muscle layer is not nodular, lack of vessels adjacent to areas of tumor penetration
Score 2	Minimal extramural stranding/nodular extension, but not in the vicinity of any vessels
Score 3	Extramural vessels adjusted to the tumor, but these vessels are of normal caliber, and there is no definite tumor signal within the vessel
Score 4	Intermediate signal intensity apparent within the vessels, although the contour and caliber of these vessels are only slightly expanded
Score 5	Obvious irregular vessel contour or nodular expansion of the vessel by definite tumor signal