Abstract: An ideal assessment is an essential aspect for patients with rectal cancer in personal treatment management and prognosis prediction. Magnetic resonance imaging (MRI) plays a central role in this process. Highresolution MRI can be used to accurately measure the depth of extramural rectal cancer spread. Therefore, highresolution MRI can define the tumor category of rectal cancer in accordance with American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC). MRI can detect the extramural venous invasion that has been demonstrated as an independently predicting factor for prognosis and survival of patients. In addition, MRI defines the tumor and relevant anatomy, providing the most detail on treatment choice.