Magnetic resonance imaging of rectal cancer.

This article aims to discuss the anatomy of the anorectum, the MRI protocol parameters required to optimize diagnosis of rectal cancer, and the diagnostic MRI criteria essential to stage rectal cancer accurately, using the TNM staging classification. A brief review of more emerging important aspects of rectal cancer staging, such as the circumferential resection margin, extramural vascular invasion, and the staging of low rectal cancers, will also be provided. Finally, the authors will touch upon the evaluation of tumor response to neoadjuvant chemoradiation therapy in the setting of locally advanced rectal cancer.