Tumor deposits on MRI in rectal cancer—detection and differentiation from lymph nodes with histopathological correlation

Questions Tumor deposits and lymph node metastasis are important factors for staging rectal cancer, but the ability of pre-operative MRI to detect and differentiate them remains unclear. Findings In low-risk rectal cancer patients treated with primary surgery, tumor deposits and lymph node metastasis are often small (≤ 5 mm) and not detected by MRI. Clinical relevance MRI has a limited ability to identify and differentiate small (≤ 5 mm) tumor deposits and lymph node metastasis in rectal cancer, which must be considered during pre-operative staging and neoadjuvant treatment planning.