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