[Local imaging of rectal cancer--update 2015: MRI as imaging biomarker].
The significance of state of the art magnetic resonance imaging (MRI) for rectal cancer goes far beyond the detection and diagnostics of local dispersion and is increasingly focusing on patient prognosis. The identification of prognostic factors, such as tumor (T) and nodal (N) status, involvement of the circumferential resection margin, presence of extramural vascular invasion, tumor response prediction following neoadjuvant therapy, therapy-related changes in microcirculation, permeability and tissue cellularity and structured reporting are important elements of advanced rectal cancer imaging. In this context, multiparametric MRI is progressively evolving into a powerful imaging biomarker.