Prognostic significance of magnetic resonance imaging-detected extramural vascular invasion in rectal cancer

Abstract Background Extramural vascular invasion (EMVI) is a poor prognostic feature in colorectal cancer. The accuracy of magnetic resonance imaging (MRI) in detecting EMVI and predicting relapse-free survival (RFS) was compared retrospectively with the histological reference standard. Methods Preoperative magnetic resonance images from patients diagnosed with rectal and sigmoid cancer were reviewed and an MRI-EMVI score (range 0 to 4) was assigned. Comparison was made with histology and clinical outcome. Results Some 142 patients with a median follow-up of 3·3 (range 0·9–5·7) years were reviewed. Histological EMVI was reported in a quarter of patients. The sensitivity and specificity of MRI detection of EMVI in 94 patients undergoing primary surgery were 62 and 88 per cent respectively. On univariable analysis, RFS at 3 years was 35 per cent for patients with an MRI-EMVI score of 3–4, compared with 74 per cent for those with a score of 0–2 (P < 0·001), similar to values in patients with positive and negative histological EMVI status respectively (34 versus 73·7 per cent; P < 0·001). Conclusion High MRI-EMVI scores may help in predicting disease relapse.