title: Rectal cancer: assessment of response to neoadjuvant chemoradiation by dynamic contrast-enhanced MRI.
abstract: OBJECTIVE
  To assess pretreatment functional and morphological tumor characteristics with magnetic resonance imaging (MRI) in advanced rectal carcinoma and to identify factors predicting response to neoadjuvant chemoradiation.
  
  
  METHODS
  In a prospective study, 95 patients with rectal carcinoma underwent dynamic contrast-enhanced MRI before and after chemoradiation. Quantitative parameters were derived from a pharmacokinetic two-compartment model. Tumors were also characterized with regard to mucinous status at pretreatment high-resolution MRI as nonmucinous or mucinous. Response to treatment was defined as a downshift in the local tumor stage.
  
  
  RESULTS
  The parameter k21 (contrast medium exchange rate) was higher at pretreatment MRI in nonmucinous compared with mucinous carcinomas (P < 0.001). The effect of chemoradiation on dynamic MR parameters was higher in nonmucinous carcinomas than in the mucinous subtype (P < 0.001). A higher rate of response to treatment was linked with nonmucinous morphology (P < 0.001). Multivariate analysis revealed an association between mucinous tumor morphology and poor response (odds ratio [95% confidence interval]: 0.113 [0.032-0.395], P < 0.001) as well as an association between a high 75th percentile of k21 and a higher response rate (odds ratio: 1.043 [1.001-1.086], P = 0.019).
  
  
  CONCLUSIONS
  Functional and morphological parameters of pretreatment MRI can assess tumor characteristics associated with the effectiveness of chemoradiation before treatment initiation.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University, Mainz, Germany. oberholz@radiologie.klinik.uni-mainz.de
authors.forename: Katja
authors.initials: K
authors.lastname: Oberholzer
authors.forename: Matthias
authors.initials: M
authors.lastname: Menig
authors.forename: Andreas
authors.initials: A
authors.lastname: Pohlmann
authors.forename: Theodor
authors.initials: T
authors.lastname: Junginger
authors.forename: Achim
authors.initials: A
authors.lastname: Heintz
authors.forename: Andreas
authors.initials: A
authors.lastname: Kreft
authors.forename: Torsten
authors.initials: T
authors.lastname: Hansen
authors.forename: Astrid
authors.initials: A
authors.lastname: Schneider
authors.forename: André
authors.initials: A
authors.lastname: Lollert
authors.forename: Heinz
authors.initials: H
authors.lastname: Schmidberger
authors.forename: Düber
authors.initials: D
authors.lastname: Christoph
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000453:epidemiology / Q000473:pathology* / Q000628:therapy*; D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant / Q000706:statistics & numerical data*; D003287:Contrast Media; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000706:statistics & numerical data; D015995:Prevalence; D011379:Prognosis; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000628:therapy*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media