Accuracy of pelvic MRI in measuring tumor height in rectal cancer patients with or without preoperative chemoradiotherapy.

INTRODUCTION

In measuring tumor height for rectal cancer, rigid sigmoidoscopy (RS) is a standard modality, and the accuracy of magnetic resonance imaging(MRI) in patients with/without preoperative chemoradiotherapy (CRT) has not been fully investigated. The aim of this study was to investigate the accuracy of MRI for measuring tumor height.

MATERIALS AND METHODS

Among rectal cancer patients seen between July 2006 and May 2012, the initial group (RS and MRI available at initial diagnosis) and the post-CRT group (RS and MRI available after the completion of preoperative CRT) were selected. Intra-class correlation coefficient (ICC) comparison tests were performed between RS and MRI results for each group.

RESULTS

Ninety-nine and 29 patients were allocated into the initial group and the post-CRT group, respectively. The tumor heights measured by RS and MRI demonstrated a positive relationship in the scatter plot (linear regression; R = 0.898; p < 0.001 in the initial group, R = 0.696; p < 0.001 in the post-CRT group). With respect to difference of absolute value (DAV) between RS and MRI, the overall mean and standard deviation of DAV were 10.9 ± 10 mm in the initial group and 8 ± 6 mm in the post-CRT group. ICC comparison analysis revealed that inter-rater agreement of RS and MRI in the initial group was significantly better than that of the post-CRT group [ICC (95% CI) 0.946 (0.919-0.963) vs. 0.823 (0.621-0.917); p = 0.004)].

CONCLUSIONS

MRI can be used as a viable option to measure tumor height in rectal cancer even in patients who have undergone preoperative CRT.