The sigmoid take-off as a landmark to distinguish rectal from sigmoid tumours on MRI: Reproducibility, pitfalls and potential impact on treatment stratification

Nino Bogveradze*, Doenja M J Lambregts, Najim El Khababi, Raphaëla C Dresen, Monique Maas, Miranda Kusters, Pieter J Tanis, Regina G H Beets-Tan, rectal MRI study group, Frans Bakers, Geerard Beets

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

11 Citations (Web of Science)


PURPOSE: The sigmoid take-off (STO) was recently introduced as a preferred landmark, agreed upon by expert consensus recommendation, to discern rectal from sigmoid cancer on imaging. Aim of this study was to assess the reproducibility of the STO, explore its potential treatment impact and identify its main interpretation pitfalls.

METHODS: Eleven international radiologists (with varying expertise) retrospectively assessed n = 155 patients with previously clinically staged upper rectal/rectosigmoid tumours and re-classified them using the STO as completely below (rectum), straddling the STO (rectosigmoid) or completely above (sigmoid), after which scores were dichotomized as rectum (below/straddling STO) and sigmoid (above STO), being the clinically most relevant distinction. A random subset of n = 48 was assessed likewise by 6 colorectal surgeons. .

RESULTS: Interobserver agreement (IOA) for the 3-category score ranged from κ0.19-0.82 (radiologists) and κ0.32-0.72 (surgeons), with highest scores for the most experienced radiologists (κ0.69-0.76). Of the 155 cases, 44 (28%) were re-classified by ≥ 80% of radiologists as sigmoid cancers; 36 of these originally received neoadjuvant treatment which in retrospect might have been omitted if the STO had been applied. Main interpretation pitfalls were related to anatomical variations, borderline cases near the STO and angulation of axial imaging planes.

CONCLUSIONS: Good agreement was reached for experienced radiologists. Despite considerable variation among less-expert readers, use of the STO could have changed treatment in ±1/4 of patients in our cohort. Identified interpretation pitfalls may serve as a basis for teaching and to further optimize MR protocols.

Original languageEnglish
Pages (from-to)237-244
Number of pages8
JournalEuropean Journal of Surgical Oncology
Issue number1
Publication statusPublished - Jan 2022


  • Adult
  • Aged
  • Aged, 80 and over
  • Anatomic Landmarks
  • Anatomic Variation
  • Carcinoma/diagnostic imaging
  • Chemoradiotherapy
  • Colectomy
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neoadjuvant Therapy
  • Observer Variation
  • Proctectomy
  • Rectal Neoplasms/diagnostic imaging
  • Reproducibility of Results
  • Sigmoid Neoplasms/diagnostic imaging
  • MRI
  • Sigmoid cancer
  • Rectal cancer
  • Sigmoid take-off

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