title: Strain Elastography Evaluation of Rectal Tumors: Inter- and Intraobserver Reproducibility.
abstract: OBJECTIVE
  Elastography is a promising method for the identification and differentiation of malignant tissue in several organ systems. The primary aim was to evaluate the inter- and intraobserver reproducibility of endorectal strain elastography differentiation of adenomas and adenocarcinomas. The secondary aim was to compare the performance of strain elastography to endorectal ultrasonography (ERUS) examinations.
  
  
  METHODS
  Consecutive inclusion of 95 ERUS examinations and 110 elastography video loops with ERUS overlay mode. Video loops were randomized and evaluated by eight observers on two separate occasions. Observers were blinded to all clinical information except the circumferential location of the tumor. A continuous visual analog scale (VAS) and a categorical scale (W-score) were used for elastography evaluation. ERUS loops were T-staged according to the TNM classification system. Histopathological evaluation of surgical resection specimen was used as the reference standard.
  
  
  RESULTS
  Strain elastography visual evaluation yielded intraobserver variability from 0.86 to 0.97 and interobserver variability of 0.99. VAS strain elastography differentiation of adenomas (pT0) and adenocarcinomas (pT1 - 4) yielded sensitivity, specificity, accuracy, positive and negative predictive values of 0.94, 0.71, 0.89, 0.92 and 0.78, respectively. The corresponding ERUS values were 0.83, 0.64, 0.79, 0.88 and 0.54, respectively.
  
  
  CONCLUSIONS
  Visual evaluation of elastography loops is highly reproducible in an offline setting with blinded observers, and correlates significantly with pT-stages. Strain elastography performs better than ERUS and might consequently improve staging.
authors: Department of Clinical Medicine, University of Bergen, Norway.
authors: J E R
authors: JE
authors: Waage
authors: Department of Radiology, DCCG South Vejle Hospital, Vejle, Denmark.
authors: S R
authors: SR
authors: Rafaelsen
authors: Department of Gastrointestinal Surgery, Cheltenham General Hospital, Cheltenham, UK.
authors: N R
authors: NR
authors: Borley
authors: Department of Clinical Medicine, University of Bergen, Norway.
authors: R F
authors: RF
authors: Havre
authors: Department of Surgery, Haukeland University Hospital, Bergen, Norway.
authors: E T
authors: ET
authors: Gubberud
authors: Department of Pathology, Haukeland University Hospital, Bergen, Norway.
authors: S
authors: S
authors: Leh
authors: Department of Surgery A, OUH Svendborg Hospital, Svendborg, Denmark.
authors: T
authors: T
authors: Kolbro
authors: Department of Surgery, Bispebjerg University Hospital, Copenhagen, Denmark.
authors: K K
authors: KK
authors: Hagen
authors: Department of Global Public Health and Primary Care, University of Bergen, Norway.
authors: G E
authors: GE
authors: Eide
authors: Department of Clinical Medicine, University of Bergen, Norway.
authors: F
authors: F
authors: Pfeffer
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D054459:Elasticity Imaging Techniques / Q000379:methods*; D019160:Endosonography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D015588:Observer Variation; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D012007:Rectum / Q000000981:diagnostic imaging / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method