Fig. 9

Coronal T2-weighted image (a) and axial T2-weighted cross sections at two different levels (b, c) of a 48 year old female patient with a cT4b rectal tumour based on invasion of the left external anal sphincter (white arrow in a; = skeletal muscle invasion), invasion of the pelvic floor (black arrow in a; = skeletal muscle invasion), invasion of the obturator compartment (arrowheads in b; = invasion of compartment outside the mesorectum), and invasion of the vagina (white arrow in b; = organ invasion). There is also a close relation to the sacral nerve plexus (white dotted lines) on the left side (arrowhead in c)