Evaluation of Extramural Venous Invasion by Diffusion-Weighted Magnetic Resonance Imaging and Computed Tomography in Rectal Adenocarcinoma

Purpose: The aim of this study is to evaluate the diagnostic contribution of diffusion-weighted magnetic resonance imaging (MRI) and computed tomography (CT) to distinguish extramural venous invasion (EMVI) in rectal adenocarcinoma. Materials and Methods: Fifty-eight patients who had been diagnosed with rectal adenocarcinoma (30 patients with EMVI and 28 patients without EMVI) were enrolled in the study. Apparent diffusion coefficient (ADC) values of the tumour and the EMVI (+) vein, the lengths of the tumours were measured on MRI. The diameters of the superior rectal vein (SRV)-inferior mesenteric vein (IMV) and distant metastatic spread were evaluated on CT. The ability of these findings to detect EMVI was assessed using receiver operating characteristic (ROC) analysis. Pathology was accepted as the reference test for EMVI. Results: Mean diameters of the SRV (4.9 +/- 0.9 mm vs 3.7 +/- 0.8 mm) and IMV (6.9 +/- 0.8 mm vs 5.4 +/- 0.9 mm) were significantly larger (P < .001) and tumour ADC values were significantly lower (0.926 +/- 0.281 x 10(-3)mm(2)/s vs 1.026 +/- 0.246 x 10 -3 mm(2)/s; P = .032) in EMVI (+) patients. Diameters of 3.95 mm for the SRV (area under the curve [AUC] +/- standard error [SE]: 0.851 +/- 0.051, P < .001, sensitivity: 93.3%, specificity: 67.9%) and 5.95 mm for the IMV (AUC + SE: 0.893 +/- 0.040, P < .001, sensitivity: 93.3%, specificity: 71.4%) and an ADC value of 0.929 x 10(-3)mm(2)/s (AUC +/- SE: 0.664 +/- 0.072, P = .032 sensitivity: 76.7%, specificity: 57.1%) were found to be cutoff values, determined by ROC analysis, for detection of EMVI. Distant metastases were significantly more prevalent in EMVI (+) patients (P < .001). Conclusion: The measurement of ADC values and SRV-IMV diameters seems to have contribution for diagnosis of EMVI in rectal adenocarcinoma. EMVI (+) patients appear to have higher risks of distant metastases at diagnosis.