The Relationship Between MR Demonstration of Extramural Venous Invasion and Nodal Disease in Rectal Cancer

Purpose: To investigate the relationship between extramural venous invasion (EMVI) detected at T2-weighted MRI and nodal disease rectal cancer compared with histopathology. Materials and Methods: The MR imaging of 79 consecutive patients with rectal cancer who underwent primary rectal surgery without neoadjuvant treatment were reviewed. MR images were scored by an expert radiologist for the presence and degree of EMVI using a five point scale blinded to pathological findings. Receiver operating characteristic curve analyses were performed to determine the sensitivity and specificity of MRI scoring in predicting EMVI and nodal disease at histopathology. Results: Compared with histology, an MR score of > 2 was found to have 100% sensitivity (95% CI: 77%-100%) and 89% specificity (95% CI: 79%-96%) in identifying EMVI involving veins > 3 mm in diameter. An EMVI score of > 2 was had a sensitivity of 56% (95% CI: 30%-80%) and specificity of 81% (95% CI: 69%-90%) for identifying patients with stage N2 disease. Conclusions: EMVI score of > 2 on T2-weighted MR imaging has a high sensitivity and specifi city for histopathologically proven extramural venous invasion involving venules > 3 mm in diameter. However, EMVI scores have only moderate sensitivity in the predicting nodal involvement.