title: Assessment of response to chemoradiation therapy in rectal cancer using MR volumetry based on diffusion-weighted data sets: a preliminary report.
abstract: OBJECTIVE
  This study evaluated the feasibility of magnetic resonance (MR) volumetry using a diffusion-weighted data set (V(DWI)) and compared it with conventional T2-weighted volumetry (V(C)) in patients affected by rectal cancer treated with chemoradiation therapy (CHRT).
  
  
  METHODS
  Fourteen patients with a biopsy diagnosis of rectal cancer underwent MR examination before and after CHRT. T2-weighted images were used to extrapolate V(C). A diffusion-weighted (DW) sequence was acquired [spin-echo diffusion-weighted echo-planar imaging (SE-DW-EPI)] with a b-value of 800 s/mm(2) and volume (V(DWI)) was calculated by semiautomatic segmentation of tumour hyperintensity. Two radiologists independently assessed volumes and analysed data in order to establish interobserver agreement and compare and correlate volumes to tumour regression grade (TRG), as evaluable at pathological examination of the surgical specimen.
  
  
  RESULTS
  Interobserver agreement was 0.977 [(95% confidence interval (CI) 0.954-0.989) and 0.956 (95% CI 0.905-0.980) for V(C) and V(DWI) and 0.964 (95% CI 0.896-0.988) and 0.271 (95% CI-0.267 to 0.686) between V(C) and V(DWI) before and after CHRT. The correlation between TRG and V(C) and V(DWI) was, respectively, rho = 0.597 (p<0.05) and r(2)=0.156 (p=0.162) and rho=0.847 (p<0.001).
  
  
  CONCLUSIONS
  V(DWI) seems to be a promising tool for assessing response to CHRT in rectal cancer. Further studies on large series of patients are needed to refine the technique and evaluate its potential predictive value.
authors.affiliation: UOC di Radiologia Universitaria, Istituto Toscano Tumori, Azienda Ospedaliera Universitaria Senese, Università degli Studi di Siena, Viale Bracci, 53100, Siena, Italy. fracarb@gmail.com
authors.forename: S F
authors.initials: SF
authors.lastname: Carbone
authors.forename: L
authors.initials: L
authors.lastname: Pirtoli
authors.forename: V
authors.initials: V
authors.lastname: Ricci
authors.forename: D
authors.initials: D
authors.lastname: Venezia
authors.forename: T
authors.initials: T
authors.lastname: Carfagno
authors.forename: S
authors.initials: S
authors.lastname: Lazzi
authors.forename: V
authors.initials: V
authors.lastname: Mourmouras
authors.forename: B
authors.initials: B
authors.lastname: Lorenzi
authors.forename: L
authors.initials: L
authors.lastname: Volterrani
mesh_terms: D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001706:Biopsy; D059248:Chemoradiotherapy / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D000077150:Oxaliplatin; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin