27 Pearls and pitfalls of structured staging and reporting of rectal cancer on MRI 2 Level of sphincter involvement IOA to assess the presence of sphincter involvement (yes/ no) were high but results to assess the level of sphincter involvement were considerably poorer with an agreement of only 51% compared to the expert reference. This was probably (partly) related to suboptimal image angulation: when re-reviewing all the cases with suspected sphincter involvement, a dedicated coronal sequence angled parallel to the anal canal was only available in 38% of these cases (see Figure 4). Figure 4 Example of a case with suspect sphincter involvement. The coronal sequence is angled parallel to the distal rectum (rather than to the anal canal), making it more difficult to assess the level of sphincter involvement. The two experts assessed this case as suspicious for intersphincteric involvement, mainly based on the transverse sequence (arrow). Results of the study readers were highly variable; 19% considered it as no sphincter invasion, 19% as internal sphincter invasion only, 19% as extending into the intersphincteric space, and 43% as extending into the external sphincter.
RkJQdWJsaXNoZXIy MjY0ODMw