title: Locally advanced rectal cancer: Qualitative and quantitative evaluation of diffusion-weighted MR imaging in the response assessment after neoadjuvant chemo-radiotherapy.
abstract: OBJECTIVE
  to investigate the added value of qualitative and quantitative evaluation of diffusion weighted (DW) magnetic resonance (MR) imaging in response assessment after neoadjuvant chemo-radiotherapy (CRT) in patients with locally advanced rectal cancer (LARC).
  
  
  METHODS
  31 patients with LARC (stage ≥ T3) were enrolled in the study. All patients underwent conventional MRI and DWI before starting therapy and after neoadjuvant CRT. All patients underwent surgery; pathologic staging represented the reference standard. For qualitative analysis, two radiologists retrospectively reviewed conventional MR images and the combined set of conventional and DW MR images and recorded their confidence level with respect to complete response (ypCR). For quantitative analysis, tumor's apparent diffusion coefficient (ADC) values were measured at each examination. ADC pre-CRT, ADC post-CRT and Δ ADC post-ADC pre of the three groups of response (ypCR, partial response ypPR, stable disease ypSD) were compared. Receiver-operating characteristics (ROC) curve analysis was employed to investigate the discriminatory capability for ypCR, responders (ypCR, ypPR) and ypSD of each measure.
  
  
  RESULTS
  addition of DWI to conventional T2-weighted sequences improved diagnostic performance of MRI in the evaluation of ypCR. A low tumor ADC value in the pre-CRT examination, a high ADC value in the post-CRT examination, a high Δ ADC post-ADC pre [>0.3 (×10(-3) mm(2)/s)] were predictive of ypCR.
  
  
  CONCLUSIONS
  DW sequences improve MR capability to evaluate tumor response to CRT. Nevertheless, no functional MR technique alone seems accurate enough to safely select patients with ypCR.
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Pietro Valerio
authors.initials: PV
authors.lastname: Foti
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Privitera
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Piana
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Palmucci
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Spatola
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Bevilacqua
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Raffaele
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Salamone
authors.affiliation: Department G.F. Ingrassia-Institute of Pathology, University of Catania, Catania, Italy.
authors.forename: Rosario
authors.initials: R
authors.lastname: Caltabiano
authors.affiliation: Department G.F. Ingrassia-Institute of Pathology, University of Catania, Catania, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Magro
authors.affiliation: Department G.F. Ingrassia-Unità Operativa Chirurgia Digerente Colorettale, University of Catania, Catania, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Li Destri
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Milone
authors.affiliation: Radiodiagnostic and Radiotherapy Unit, University Hospital "Policlinico-Vittorio Emanuele", Catania, Italy.
authors.forename: Giovanni Carlo
authors.initials: GC
authors.lastname: Ettorre
keywords: Chemoradiation; Diffusion-weighted imaging; Magnetic resonance imaging; Rectal cancer; Staging; Treatment response