Diagnostic Performance of CT, MRI, and ERUS in Preoperative T- and N-Staging of Colorectal Cancer: A Retrospective Single-Center Analysis.

[PURPOSE] This study evaluates the accuracy of computed tomography (CT), magnetic resonance imaging (MRI), and endorectal ultrasound (ERUS) in preoperative staging of colon and rectal cancers, comparing imaging results with histopathological findings. The aim is to identify strengths and limitations of each modality to optimize therapeutic strategies, particularly for neoadjuvant therapy in locally advanced cases.

[METHODS] This retrospective study analyzed 487 patients treated surgically for colon and rectal cancers between 2012 and 2018. Patients with incomplete imaging or histopathological data were excluded. Preoperative staging with CT, MRI, and ERUS was assessed against histopathological findings, focusing on sensitivity, specificity, and predictive accuracy (PAC). Statistical analyses were conducted to evaluate the performance of each modality for tumor (T) and nodal (N) staging, as well as risk stratification for low-risk (T1/T2) and high-risk (T3/T4) tumors.

[RESULTS] MRI showed the highest PAC for rectal cancer (89% for T-staging, 82% for N-staging), particularly for advanced tumors. CT achieved robust results for colon cancer, with PACs of 82% for T-staging and 73% for N-staging. ERUS demonstrated high accuracy for early rectal cancer, achieving an 85% PAC for low-risk tumors but performed weaker for advanced cases. MRI and CT outperformed ERUS in detecting advanced-stage tumors and nodal involvement. Risk stratification analysis confirmed MRI's superiority in rectal cancer and CT's consistency in colon cancer staging.

[CONCLUSION] MRI is the modality of choice for rectal cancer staging, while CT remains the cornerstone for colon cancer staging. ERUS is best suited for early rectal tumors. These findings highlight the complementary roles of these imaging modalities and underline the need for advanced techniques to enhance diagnostic accuracy in colorectal cancer management.