Extramural vascular invasion (EMVI) was defined as the presence of tumor cells within an endothelium-lined vessel beyond the muscularis propria. High-resolution MRI had 100% sensitivity and 89% specificity in identification of large (caliber greater than 3 mm) EMVI with histopathology as reference. EMVI detected by both histopathology and MRI was significantly associated with local recurrence, distance metastasis and tumor-related death in rectal cancer, which was also identified as an independent prognostic factor for 3-year tumor-free survival and overall survival. EMVI could be used as one of the risk factors, which would allow stratification of patients with rectal cancer to receive neoadjuvant chemoradiotherapy (neoCRT). Moreover, EMVI detected by high-resolution MRI was identified as an independent predictor for response to neoCRT. Tumor regression grading scale defined by high-resolution MRI could be used to evaluate EMVI regression after neoCRT.

Rectal neoplasms; Extramural vascular invasion; Magnetic Resonance Imaging