Fig. 11

Extramural venous invasion in neuroendocrine tumor. A 50-year-old man with poorly differentiated neuroendocrine tumor, large-cell type. On the T2WI a tubular structure with irregular margins and signal intensity similar to the tumor (a arrow) extends from the rectal mass (a asterisk). The primary lesion (b asterisk) and extramural venous invasion (b arrow) are more conspicuous on DWI. Mesorectal lymph nodes which were histopathologically proven to be nodal metastases are depicted on T2WI and DWI (a, b arrowheads)