MRI of a T4b rectal cancer

Axial T2-weighted MRI image of a T4b rectal cancer shows a large, polypoidal, T2 hyperintense mass that fills the low rectum (arrowheads). The mass breaches the bowel wall and the pelvic floor musculature (arrows) with gross extension into the perineal fat. The tumor had mucinous histology that was responsible for the T2 hyperintense appearance.