title: Predicting response to neoadjuvant chemoradiation therapy in locally advanced rectal cancer: diffusion-weighted 3 Tesla MR imaging.
abstract: OBJECTIVE
  To evaluate the efficacy of diffusion-weighted imaging (DWI) on 3 Tesla (T) MR imaging to predict the tumor response to neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.
  
  
  METHODS
  Thirty-five patients who underwent neoadjuvant CRT and subsequent surgical resection were included. Tumor volume was measured on T2-weighted MR images before and after neoadjuvant CRT and the percentage of tumor volume reduction was calculated. The apparent diffusion coefficient (ADC) value was measured on the DWI before and after neoadjuvant CRT, and the change of ADC (Δ ADC) was calculated. The histopathologic response was categorized either as a responder to CRT or as a nonresponder. The relationship between the ADC parameters and the percentage of tumor volume reduction or histopathologic response was then evaluated.
  
  
  RESULTS
  There was a significant correlation between tumor volume reduction and pre-CRT ADC and Δ ADC, respectively (r = -0.352, r = 0.615). Pre-CRT ADC of the histopathologic responders was significantly lower than that of the histopathologic nonresponders (P = 0.034). Δ ADC of the histopathologic responders was significantly higher than that of the histopathologic nonresponders (P < 0.005).
  
  
  CONCLUSIONS
  DWI on 3T MR imaging may be a promising technique for helping to predict and monitor the treatment response to neoadjuvant CRT in patients with locally advanced rectal cancer.
authors: Department of Radiology, Chonnam National University Hospital, Dong-gu, Gwangju, South Korea.
authors: Se Hee
authors: SH
authors: Jung
authors: Suk Hee
authors: SH
authors: Heo
authors: Jin Woong
authors: JW
authors: Kim
authors: Yong Yeon
authors: YY
authors: Jeong
authors: Sang Soo
authors: SS
authors: Shin
authors: Min-Gyu
authors: MG
authors: Soung
authors: Heong Rok
authors: HR
authors: Kim
authors: Heoung Keun
authors: HK
authors: Kang
mesh_terms: D000368:Aged; D059248:Chemoradiotherapy; D003952:Diagnostic Imaging / Q000379:methods; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D009362:Neoplasm Metastasis; D011379:Prognosis; D012004:Rectal Neoplasms / Q000188:drug therapy* / Q000473:pathology* / Q000532:radiotherapy*; D015203:Reproducibility of Results; D016896:Treatment Outcome