title: Dynamic contrast-enhanced MRI to evaluate the therapeutic response to neoadjuvant chemoradiation therapy in locally advanced rectal cancer.
abstract: OBJECTIVE
  To evaluate the usefulness of perfusion parameters derived from dynamic contrast-enhanced MR imaging (DCE-MRI) for assessing the therapeutic response to neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer (LARC).
  
  
  METHODS
  Fifty patients with LARC (≥T3 or lymph-node metastasis) who underwent CRT and subsequent surgery, were included in this study. All patients underwent pre- and post-CRT DCE-MRI on a 1.5 Tesla unit. By using a postprocessing software, the following perfusion parameters (K(trans) , kep , ve ) were measured for tumor. Those perfusion parameters were compared not only between the T-downstaged group and the nondownstaged group, but also before and after CRT in each group.
  
  
  RESULTS
  After CRT, the mean K(trans) (min(-1) ) significantly decreased from 1.24 ± 0.53 to 0.76 ± 0.45 in the T-downstaged group (n = 24) (P = 0.0007), whereas it did not significantly decrease in the nondownstaged group (n = 26) (from 1.02 ± 0.53 to 0.87 ± 0.48, P = 0.24). The percentage difference between pre- and post-CRT K(trans) in the T-downstaged group was significantly higher than that in the nondownstaged group (43%, 16%, respectively, P = 0.0092). However, none of the other parameters showed significant differences.
  
  
  CONCLUSIONS
  A large decrease in the mean K(trans) after CRT was associated with a good therapeutic response to CRT for LARC.
authors.affiliation: Department of Radiology, Inje University Haeundae Paik Hospital, Inje University College of Medicine, Haeundae-gu, Busan, Korea.
authors.forename: Seung Ho
authors.initials: SH
authors.lastname: Kim
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Sandeep N
authors.initials: SN
authors.lastname: Gupta
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000368:Aged; D059248:Chemoradiotherapy; D003131:Combined Modality Therapy; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020360:Neoadjuvant Therapy / Q000379:methods*; D009367:Neoplasm Staging; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: chemoradiation; dynamic contrast-enhanced magnetic resonance imaging; neoplasms; perfusion; rectum; therapeutic response