Diagnostic Performance of Diffusion-Weighted and Conventional MR Imaging in Staging of Rectal Cancer

Abstract

Aim: To determine the diagnostic accuracy of preoperative T2-weighted (T2W) and diffusion-weighted (DWI) magnetic resonance imaging (MRI) in tumor/node (T/N) staging of rectal cancer and impact of MRI in clinical decision-making. Method: This retrospective study included 43 patients with rectal cancer who were admitted to our institution between January 2019 and December 2020. MRI was performed within 2 weeks before surgery. The diagnostic accuracy of MRI was assessed using the postoperative histopathologic results as a reference. Accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and Kappa values were determined. The impact of preoperative MRI for appropriate treatment decision-making was also assessed. Results: Overall, the diagnostic accuracy and Kappa value of T2W-MRI for T staging were 62.8% and 0.266, respectively. The diagnostic accuracy and Kappa value of combined use of T2W and DWI for T staging were 65.1% and 0.251 and 41.9% and 0.011 for N staging, respectively. The diagnostic accuracy of MRI for treatment decision-making was 72.5% and 74.5% for T2W and T2W+DWI, respectively. Conclusion: In rectal cancer, T2W-MRI enables a highly accurate preoperative assessment for the T stage but has moderate accuracy for the N stage.