To evaluate the performance of gadolinium contrast-enhanced T1-weighted magnetic resonance imaging (CET1WI) in addition to high-resolution T2-weighted imaging (HRT2WI) for preoperative detection of extramural venous invasion (EMVI) in rectal cancer. Fifty-nine patients with rectal cancer who underwent preoperative MRI were included in this study. The likelihood of EMVI was retrospectively scored by two readers on CET1WI, HRT2WI, and HRT2WI + CET1WI, using a subjective five-point scale ranging from 0 to 4. The pathological status of EMVI was used as a standard reference. Diagnostic parameters, including area under the receiver operating curve (AUC), sensitivity, and specificity, were calculated, and the diagnostic performances of HRT2WI and HRT2WI + CET1WI were compared. Interobserver variance was also evaluated. Eighteen (30.5%) patients showed pathological EMVI. During EMVI detection, reader A obtained an AUC of 0.768, sensitivity of 72.5%, and specificity of 73.2% from HRT2WI alone; after combination with CET1WI, these values improved to 0.864, 83.3%, and 75.6%, respectively. Differences in AUC between these techniques were not significant (p = 0.056). Reader B obtained an AUC of 0.833, sensitivity of 77.8%, and specificity of 73.2% from HRT2WI alone; after combination with CET1W1, these figures were adjusted to 0.720, 50%, and 78%; differences in AUC between techniques were significant (p = 0.027). Interobserver agreement during EMVI scoring was good for HRT2WI (kappa = 0.603) and moderate for HRT2WI + CET1WI (kappa = 0.413). Although interobserver agreement decreased, combination of CET1WI with HRT2WI could improve EMVI detection.