Performance comparison between MRI and CT for local staging of sigmoid and descending colon cancer.

Purpose: To compare the diagnostic performance of MRI and CT for local staging of sigmoid and descending colon cancer, with pathological results as the reference standard.

Method: This retrospective study included 116 patients with sigmoid or descending colon cancer who underwent both MRI and CT before surgery. MRI and CT images were separately reviewed by two independent and blinded radiologists to assess the following features: T-stage, presence of extramural extension (T3-4 disease), lymph node metastases (N+), and extramural vascular invasion (EMVI+). Diagnostic performance with sensitivity and specificity for detecting positive status (T3-4, N+ or EMVI+) were assessed using receiver-operating-characteristic (ROC) curve, and compared between MRI and CT.

Results: MRI achieved correct T-stage in 81 of 116 patients (69.8 %) while CT in 66 (56.9 %). For detecting T3-4 disease, MRI showed better performance than CT with area under the curve (AUC) of 0.888 versus 0.712 (P =  0.002) and specificity of 81.82 % versus 54.6 % (P =  0.011). No significance was found in sensitivity between two modalities (89.2 % versus 83.1 %, P =  0.302). For detecting N+ disease, performance of MRI and CT were similar (AUC, 0.670 versus 0.650, P =  0.412). For detecting EMVI+, MRI showed better performance than CT (AUC, 0.780 versus 0.575, P =  0.012) with significantly higher sensitivity (68.6 % versus 40.0 %, P =  0.031) and similar specificity (both are 84.3 %).

Conclusions: MRI may offer more superior diagnostic performance than CT for detecting T3-4 disease and EMVI, thereby supporting its alternative application to CT in local staging of colon cancer.