MRI's evolving role in rectal cancer in the era of personalized medicine.

Recent decades have seen great advances in the diagnosis and management of rectal cancer, and magnetic resonance imaging (MRI) has become pivotal for decision making. New treatments include total neoadjuvant therapy for locally advanced disease, with neoadjuvant immunotherapy, radiotherapy, or chemotherapy alone offering viable alternatives to conventional chemoradiotherapy. Minimally invasive surgical and endoscopic techniques and organ preservation strategies after neoadjuvant therapy have expanded personalized therapeutic options. In this scenario, where it is crucial to tailor treatment to individual patients, MRI plays a critical role in guiding management, including local staging and risk stratification, restaging, and surveillance. However, variability in assessments and limitations in identifying key clinical features (e.g., early-stage tumors, lymph-node involvement, extramural vascular invasion, and responses to treatment) are challenges that have not yet been overcome. This review provides an overview of the current role of MRI in rectal cancer, emphasizing how imaging can refine tailored treatment strategies to improve patient outcomes. It highlights the prognostic and decision-making implications of MRI-based features of local tumor spread (depth of invasion, mesorectal fascia involvement, lymph-node metastases, and perineural and lymphatic invasion) and risk of systemic dissemination (extramural vascular invasion and tumor deposits). It discusses MRI's role in supporting new therapeutic strategies (total neoadjuvant therapy, organ preservation, etc.), evaluating its limitations in assessing some key histological, molecular, and genetic features of rectal cancer as well as in assessing the response to treatment. Finally, it ponders the potential roles of advanced MRI sequences, artificial intelligence, and radiomics in clinical decision making.