The improvements in outcomes associate with the use of preoperative therapy rather than postoperative treatment means that clinical teams are increasingly reliant on imaging to identify high-risk features of disease to determine treatment plans. For many solid tumours, including rectal cancer, validated techniques have emerged in identifying prognostic factors pre-operatively. In the MERCURY study, a standardised scanning technique and the use of reporting proformas enabled consistently accurate assessment and documentation of the prognostic factors. This is now an essential tool to enable our clinical colleagues to make treatment decisions. In this review, we describe the proforma-based reporting tool that enables a systematic approach to the interpretation of the magnetic resonance images, thereby enabling all the clinically relevant features to be adequately assessed.