Role of Recent Advances of Diffusion Weighted MRI in Assessment of Therapeutic Response of Rectal Cancer

Abstract

olorectal cancer is the third most common cancer in males and the second most common cancer in females; around 30-40% of colorectal cancers are located in the rectum. The advance in treatment of rectal cancer raised the need for proper preoperative staging to individualize treatment option according to patient condition without facing unnecessary treatment.

MRI imaging proved to be the modality of choice for accurate staging of rectal cancer. It has high soft tissue contrast resolution providing excellent information regarding the site and size of tumor, the depth of mural and extramural tumor spread, involvement of the circumferential resection margin, the extent of any sphincteral involvement, extramural vascular invasion (EMVI) and lymph nodes.

Recent developments in rectal treatment urge the need for an accurate radiological response evaluation. Reduction in volume and fibrotic transformation are the two main signs of response that can be appreciated on morphological (T2-