Value of 3Tesla MRI in the preoperative staging of mid-low rectal cancer and its impact on clinical strategies

Background: To determine the diagnostic accuracy of preoperative T/N stage with magnetic resonance imaging (MRI) in lower and middle rectal cancer patients and the impacts on clinical decision-making.

Patients and methods: A total of 211 patients were recruited from October 2015 to March 2017 in this retrospective study. High-resolution MRI was performed within 2 weeks before surgery. Histopathologic results were evaluated for the postoperative T/N stage and the diagnostic accuracy of MRI was assessed according to the postoperative histopathologic results. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value were evaluated for T/N staging and κ values were used to evaluate MRI consistent analysis compared with postoperative histopathologic staging.

Results: The overall MRI diagnostic accuracy was 79.62% for T1-4 staging and 54.50% for N0-2 staging. The κ values were 0.619 and 0.255 for T1-4 and N0-2 staging, respectively. The diagnostic accuracy of MRI for treatment decision-making was 80.57%.

Conclusion: MRI allows a highly accurate preoperative assessment of T stage but only a fairly accurate preoperative assessment of N stage for rectal cancer. The diagnostic accuracy of MRI for treatment decision-making is promising, but additional studies are needed to validate these findings in a larger sample size from multiple centers.

Keywords: diagnostic accuracy; histopathology; magnetic resonance imaging staging; rectal cancer.