Importance and Qualitative Requirements of Magnetic Resonance Imaging for Therapy Planning in Rectal Cancer - Interdisciplinary Recommendations of AIO, ARO, ACO and the German Radiological Society

Due to its excellent intrinsic soft tissue contrast, magnetic resonance imaging allows excellent visualization and anatomical separation of therapy-relevant risk structures such as the mesorectal fascia, local lymph nodes, and vascular structures in patients with rectal carcinoma. This makes magnetic resonance imaging (MRI) a valuable evaluation method for further therapeutic stratification. In particular, MRI is indispensable for the decision to refrain from neoadjuvant therapy and to choose a primary surgical approach. In addition to the oncologically generally relevant T-, N-, and M-criteria, two further parameters are included: the extramural vascular infiltration and the circumferential resection margin. Due to the significant impact of MRI on further therapeutic decision-making, standardized MR image quality is considered essential. Key Points: Magnetic resonance imaging is a valuable evaluation method for further therapeutic stratification. Critical anatomic landmarks for evaluation are circumferential resection margins.