title: Interobserver agreement of radiologists assessing the response of rectal cancers to preoperative chemoradiation using the MRI tumour regression grading (mrTRG).
abstract: OBJECTIVE
  To investigate whether the magnetic resonance imaging (MRI) tumour regression grading (mrTRG) scale can be taught effectively resulting in a clinically reasonable interobserver agreement (>0.4; moderate to near perfect agreement).
  
  
  METHODS
  This study examines the interobserver agreement of mrTRG, between 35 radiologists and a central reviewer. Two workshops were organised for radiologists to assess regression of rectal cancers on MRI staging scans. A range of mrTRGs on 12 patient scans were used for assessment.
  
  
  RESULTS
  Kappa agreement ranged from 0.14-0.82 with a median value of 0.57 (95% CI: 0.37-0.77) indicating good overall agreement. Eight (26%) radiologists had very good/near perfect agreement (κ>0.8). Six (19%) radiologists had good agreement (0.8≥κ>0.6) and a further 12 (39%) had moderate agreement (0.6≥κ>0.4). Five (16%) radiologists had a fair agreement (0.4≥κ>0.2) and two had poor agreement (0.2>κ). There was a tendency towards good agreement (skewness: 0.92). In 65.9% and 90% of cases the radiologists were able to correctly highlight good and poor responders, respectively.
  
  
  CONCLUSIONS
  The assessment of the response of rectal cancers to chemoradiation therapy may be performed effectively using mrTRG. Radiologists can be taught the mrTRG scale. Even with minimal training, good agreement with the central reviewer along with effective differentiation between good and intermediate/poor responders can be achieved. Focus should be on facilitating the identification of good responders. It is predicted that with more intensive interactive case-based learning a κ>0.8 is likely to be achieved. Testing and retesting is recommended.
authors.affiliation: Department of Colorectal Surgery, Croydon University Hospital, Croydon CR7 7YE, UK; Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK; Imperial College London, London, UK.
authors.forename: M R S
authors.initials: MR
authors.lastname: Siddiqui
authors.affiliation: Dr Jones and Partners, Adelaide, South Australia, Australia.
authors.forename: K L
authors.initials: KL
authors.lastname: Gormly
authors.affiliation: Department of Colorectal Surgery, Croydon University Hospital, Croydon CR7 7YE, UK; Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK; Imperial College London, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Bhoday
authors.affiliation: Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK.
authors.forename: S
authors.initials: S
authors.lastname: Balyansikova
authors.affiliation: Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Battersby
authors.affiliation: Department of Surgery, University College London, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Chand
authors.affiliation: Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK.
authors.forename: S
authors.initials: S
authors.lastname: Rao
authors.affiliation: Department of Surgery, Royal Marsden Hospital, Fulham Rd, London SW3 6JJ, UK; Imperial College London, London, UK.
authors.forename: P
authors.initials: P
authors.lastname: Tekkis
authors.affiliation: Department of Colorectal Surgery, Croydon University Hospital, Croydon CR7 7YE, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Abulafi
authors.affiliation: Department of Radiology, Royal Marsden Hospital, Sutton, Surrey SM2 5PT, UK; Imperial College London, London, UK. Electronic address: gina.brown@rmh.nhs.uk.
authors.forename: G
authors.initials: G
authors.lastname: Brown
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D002983:Clinical Competence; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D060787:Neoplasm Grading; D015588:Observer Variation; D011300:Preoperative Care / Q000379:methods; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents