title: Locally advanced rectal cancer: is diffusion weighted MRI helpful for the identification of complete responders (ypT0N0) after neoadjuvant chemoradiation therapy?
abstract: OBJECTIVE
  To determine retrospectively the additional value of DWI-MRI toT2-MRI for predicting complete response (ypT0N0 = CR) after chemoradiation-therapy (CRT) in locally advanced rectal cancer.
  
  
  METHODS
  Seventy locally advanced rectal cancer patients underwent CRT followed by restaging MRI and resection. Two readers with different experience levels independently scored T2 images for CR and, in a second reading, combined T2 and DWI. A 5-point confidence-level score was used to generate ROC curves. Areas under the ROC curves (AUC) and interobserver agreement were compared for both readings. Histology served as reference standard.
  
  
  RESULTS
  The interobserver agreement increased after addition of DWI from 0.35 to 0.58 but the AUC improved only for the experienced reader (0.77 to 0.89, p = 0.005 vs. 0.74 to 0.70, p > 0.05). Sensitivity and NPV improved from 20-30 % to 40-70 %, respectively 88 % to 91-95 %. Specificity and PPV improved only for the experienced reader (87 to 93 % respectively 27 to 63 %).
  
  
  CONCLUSIONS
  Adding DWI to T2-MRI improves consistency between readers and has potential to improve readers' accuracy dependent on his/her experience. DWI could be of additional value, particularly in ruling out CR (high NPV), but considering the sub-optimal PPV one should be cautious about relying solely on MRI for the clinical decision to offer a wait-and-see strategy.
authors.affiliation: Department of Radiology, Atrium Medical Center Parkstad, P.O. Box 4446, 6401 CX, Heerlen, The Netherlands, sandersassen@yahoo.com.
authors.forename: S
authors.initials: S
authors.lastname: Sassen
authors.forename: M
authors.initials: M
authors.lastname: de Booij
authors.forename: M
authors.initials: M
authors.lastname: Sosef
authors.forename: R
authors.initials: R
authors.lastname: Berendsen
authors.forename: G
authors.initials: G
authors.lastname: Lammering
authors.forename: R
authors.initials: R
authors.lastname: Clarijs
authors.forename: M
authors.initials: M
authors.lastname: Bakker
authors.forename: R
authors.initials: R
authors.lastname: Beets-Tan
authors.forename: F
authors.initials: F
authors.lastname: Warmerdam
authors.forename: R
authors.initials: R
authors.lastname: Vliegen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D059248:Chemoradiotherapy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000473:pathology; D011237:Predictive Value of Tests; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy*; D012074:Remission Induction; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome