title: Diffusion-weighted MR imaging in liver metastases of colorectal cancer: reproducibility and biological validation.
abstract: OBJECTIVE
  Before diffusion-weighted imaging (DWI) can be implemented in standard clinical practice for response monitoring, data on reproducibility are needed to assess which differences outside the range of normal variation can be detected in an individual patient. In this study we assessed the reproducibility of the apparent diffusion coefficient (ADC) values in colorectal liver metastases. To provide a biological basis for these values, their relation with histopathology was assessed.
  
  
  METHODS
  DWI was performed twice in 1 week in patients scheduled for metastasectomy of colorectal liver metastases. Correlation between ADC values and apoptosis marker p53, anti-apoptotic protein BCL-2, proliferation marker Ki67 and serum vascular endothelial growth factor (VEGF) concentration were assessed.
  
  
  RESULTS
  A good reproducibility coefficient of the mean ADC (coefficient of reproducibility 0.20 × 10(-3) mm(2)/s) was observed in colorectal liver metastases (n = 21). The ADC value was related to the proliferation index and BCL-2 expression of the metastases. Furthermore, in metastases recently treated with systemic therapy, the ADC was significantly higher (1.27 × 10(-3) mm(2)/s vs 1.05 × 10(-3) mm(2)/s, P = 0.02).
  
  
  CONCLUSIONS
  The good reproducibility, correlation with histopathology and implied sensitivity for systemic treatment-induced anti-tumour effects suggest that DWI might be an excellent tool to monitor response in metastatic colorectal cancer.
authors.affiliation: Department of Medical Oncology 452, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands. L.Heijmen@onco.umcn.nl
authors.forename: Linda
authors.initials: L
authors.lastname: Heijmen
authors.forename: Edwin E G W
authors.initials: EE
authors.lastname: Ter Voert
authors.forename: Iris D
authors.initials: ID
authors.lastname: Nagtegaal
authors.forename: Paul
authors.initials: P
authors.lastname: Span
authors.forename: Johan
authors.initials: J
authors.lastname: Bussink
authors.forename: Cornelis J A
authors.initials: CJ
authors.lastname: Punt
authors.forename: Johannes H W
authors.initials: JH
authors.lastname: de Wilt
authors.forename: Fred C G J
authors.initials: FC
authors.lastname: Sweep
authors.forename: Arend
authors.initials: A
authors.lastname: Heerschap
authors.forename: Hanneke W M
authors.initials: HW
authors.lastname: van Laarhoven
mesh_terms: D000368:Aged; D002277:Carcinoma / Q000473:pathology* / Q000556:secondary*; D015179:Colorectal Neoplasms / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity