Dr. Ferdinand Bauer is a member of the rectal MRI study group and co-author
Objectives: To investigate uniformity and pitfalls in structured radiological staging of rectal cancer.
Method: Twenty-one radiologists (12 countries) staged 75 rectal cancers on MRI using a structured reporting template. Interobserver agreement (IOA) was calculated as the percentage agreement between readers (categorical variables) and Krippendorff’s α (continuous variables). Agreement with an expert consensus served as a surrogate standard of reference to estimate diagnostic accuracy. Polychoric correlation coefficients were used to assess correlations between diagnostic confidence and accuracy (=agreement with expert consensus).
Results: Uniformity to diagnose high-risk (≥cT3 ab) versus low-risk (≤cT3 cd) cT-stage, cN0 versus cN+, lateral nodes and tumour deposits, MRF and sphincter involvement, and solid versus mucinous tumours was high with IOA > 80% in the majority of cases (and >80% agreement with expert consensus). Results for assessing extramural vascular invasion, cT-stage (cT1-2/cT3/cT4a/cT4b), cN-stage (cN0/N1/N2), relation to the peritoneal reflection, extent of sphincter involvement (internal/intersphincteric/external) and morphology (solid/annular/semi-annular) were considerably poorer. IOA was high (α = 0.72–0.84) for tumour height/length and extramural invasion depth, but low for tumour-MRF distance and number of (suspicious) nodes (α = 0.05–0.55). There was a significant positive correlation between diagnostic confidence and accuracy (=agreement with expert consensus) (p < 0.001-p = 0.003).
Conclusions:– Several staging items lacked sufficient
– Results for cT- and N-staging g improved when using a dichotomized stratification.
– Considering the significant correlation between diagnostic confidence and accuracy, a confidence level may be incorporated into structured reporting for specific items with low reproducibility.
Advances in knowledge: Although structured reporting aims to achieve uniformity in reporting, several items lack sufficient reproducibility and might benefit from dichotomized assessment and incorporating confidence levels.
This medical abstract is published in the following media:
el Khababi N, Beets-Tan RG.H, Curvo-Semedo L, Tissier R, Nederend J, Lahaye MJ, et al. Pearls and pitfalls of structured staging and reporting of rectal cancer on MRI: an international multireader study. Br J Radiol (2023) 10.1259/bjr.20230091.
© 2023 The Authors. Published by the British Institute of Radiology under the terms of the Creative Commons Attribution-NonCommercial
The full-length publication in English can be found at the following link:
English version: “Pearls and pitfalls of structured staging and reporting of rectal cancer on MRI: an international multireader study”