Role of Magnetic Resonance Imaging in Primary Rectal Cancer—Standard Protocol and Beyond

New-generation magnetic resonance imaging (MRI) scanners with optimal phased-array body coils have contributed to obtainment of high-resolution T2-weighted turbo spin echo images in which visualization of anatomical details such as the mesorectal fascia and the bowel wall layers is feasible. Preoperative, locoregional staging of rectal cancer with MRI, considered standard of care nowadays, relies on these images for stratification of high-risk patients for local recurrence, patients most likely to benefit from neoadjuvant therapy, as well as patients who exhibit imaging features indicative of a high risk of metastatic disease. Functional imaging, including optimized for rectal cancer diffusion-weighted imaging and more recently use of dynamic contrast-enhanced MRI, combined with radiologists׳ rising level of familiarity regarding the assessment of reactive changes postchemoradiation treatment, have shown to increase MRI staging accuracy after neoadjuvant treatment. Our intention is to review already established standard protocols for primary rectal cancer and go through potential additional promising imaging tools.