Figure 18. Coronal T2-weighted fast spin-echo (2,500/100) MR image obtained with an endoanal coil in 45-year-old woman with fecal incontinence shows atrophy of the external sphincter (ES). Compare the thickness and signal intensity of the external sphincter with those of the nonatrophied puborectal muscle (PR) and levator ani muscle (LA) and to a normal external sphincter (see Fig 5). The external sphincter muscle is partly replaced by fat.