Multiparametric Imaging for the Locoregional Follow-up of Rectal Cancer

Abstract

To discuss the potential of multiparametric imaging for the locoregional follow-up of rectal cancer by outlining the strengths/weaknesses of anatomical imaging in specific MRI and highlighting the potential of the most relevant functional imaging and novel image post-processing techniques In addition to anatomical imaging, diffusion-weighted imaging (DWI) and PET have been most extensively studied for the locoregional follow-up of rectal cancer. Fewer (and more recent) studies have focused on the use of other functional MRI techniques, advanced post-processing methods such as Radiomics and hybrid imaging (PET-MRI). Anatomical imaging experiences difficulties in the locoregional assessment of rectal cancer after chemoradiotherapy and surgery. Addition of DWI to anatomical MRI has proven its benefit for qualitative response assessment after neoadjuvant chemoradiotherapy. PET mainly has a role for the detection of recurrent disease after surgery and may be valuable for early response prediction. Evidence for multiparametric assessment of PET combined with MRI or hybrid PET-MRI is sparse. More quantitative functional imaging techniques including DCE-MRI and advanced post-processing techniques such as Radiomics have shown potential in research settings to render biomarkers of response but require standardisation and large-scale validation, preferably in trial settings.