title: Diffusion-weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer.
abstract: To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI).
  
  
  
  We enrolled a total of 86 consecutive patients who had undergone surgery for rectal cancer after neoadjuvant chemoradiotherapy (CRT) at our institution between July 2012 and November 2014. Two radiologists who were blinded to the final pathological results reviewed post-CRT MRI to evaluate tumor stage. Quantitative image analysis was performed using T2 -weighted and diffusion-weighted images independently by two radiologists using dedicated software that performed histogram analysis to assess the distribution of ADC in the whole tumor.
  
  
  
  After surgery, 16 patients were confirmed to have achieved pCR (18.6%). All parameters from pre- and post-CRT ADC histogram showed good or excellent agreement between two readers. The minimum, 10th, 25th, 50th, and 75th percentile and mean ADC from post-CRT ADC histogram were significantly higher in the pCR group than in the non-pCR group for both readers. The 25th percentile value from ADC histogram in post-CRT MRI had the best diagnostic performance for detecting pCR, with an area under the receiver operating characteristic curve of 0.796.
  
  
  
  Low percentile values derived from the ADC histogram analysis of rectal cancer on MRI after CRT showed a significant difference between pCR and non-pCR groups, demonstrating the utility of the ADC value as a quantitative and objective marker to evaluate complete pathologic response to preoperative CRT in rectal cancer. J. Magn. Reson. Imaging 2016;44:212-220.
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Moon Hyung
authors.initials: MH
authors.lastname: Choi
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Soon Nam
authors.initials: SN
authors.lastname: Oh
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Sung Eun
authors.initials: SE
authors.lastname: Rha
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Joon-Il
authors.initials: JI
authors.lastname: Choi
authors.affiliation: Department of Hospital Pathology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Sung Hak
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Hong Seok
authors.initials: HS
authors.lastname: Jang
authors.affiliation: Department of Surgery, Seoul St. Mary's Hospital, Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Jun-Gi
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Grimm
authors.affiliation: Siemens Healthcare, Seoul, Republic of Korea.
authors.forename: Yohan
authors.initials: Y
authors.lastname: Son
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000970:Antineoplastic Agents / Q000627:therapeutic use; D059248:Chemoradiotherapy / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015588:Observer Variation; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents
keywords: apparent diffusion coefficient (ADC); chemoradiotherapy; histogram; rectal cancer