MRI interobserver reliability in rectal tumor angulation

Background: When rectal tumors are examined using magnetic resonance imaging (MRI) the perpendicular angulation of the axial T2-weighted image to the tumor axis is essential for a correct measure of the shortest distance between tumor and mesorectal facia. Purpose: The purpose of this study was to determine the interobserver variability in rectal tumor angulation between a radiologist and a radiographer. Material and Methods: Two observers performed the angulation independently. All MRI examinations were performed using an MRI 1.5 Tesla unit. A Bland-Altman plot was used to assess the interobserver variance and Intraclass correlation coefficient (ICC) statistic was used to assess the interobserver reliability. Results: MRI was performed in 55 patients with rectal cancer during a one-year period (25 (45.5%) women and 30 (54.5%) men). The median age was 71 years (range 46-87 years). The rectal tumor mean length was 3.9 cm. The interobserver reliability was good (ICC = 0.83, 95% confidence interval 0.72-0.90). Conclusion: Radiographers receiving training will be able to perform MRI rectal tumor angulation.