title: Magnetic resonance based texture parameters as potential imaging biomarkers for predicting long-term survival in locally advanced rectal cancer treated by chemoradiotherapy.
abstract: OBJECTIVE
  The study aimed to investigate whether textural features of rectal cancer on MRI can predict long-term survival in patients treated with long-course chemoradiotherapy.
  
  
  METHODS
  Textural analysis (TA) using a filtration-histogram technique of T2-weighted pre- and 6-week post-chemoradiotherapy MRI was undertaken using TexRAD, a proprietary software algorithm. Regions of interest enclosing the largest cross-sectional area of the tumour were manually delineated on the axial images and the filtration step extracted features at different anatomical scales (fine, medium and coarse) followed by quantification of statistical features [mean intensity, standard deviation, entropy, skewness, kurtosis and mean of positive pixels (MPP)] using histogram analysis. Cox multiple regression analysis determined which univariate features including textural, radiological and histological independently predicted overall survival (OS), disease-free survival (DFS) and recurrence-free survival (RFS).
  
  
  RESULTS
  MPP [fine texture, hazard ratio (HR) 6.9, 95% CI: 2.43-19.55, P < 0.001], mean (medium texture, HR 5.6, 95% CI: 1.4-21.7, P = 0.007) and extramural venous invasion (EMVI) on MRI (HR 2.96, 95% CI: 1.04-8.37, P = 0.041) independently predicted OS while mean (medium texture, HR 4.53, 95% CI: 1.58-12.94, P = 0.003), MPP (fine texture, HR 3.36, 95% CI: 1.36-8.31, P = 0.008) and threatened circumferential resection margin (CRM) on MRI (HR 3.1, 95% CI: 1.01-9.46, P = 0.046) predicted DFS. For OS, EMVI on MRI (HR 4.23, 95% CI: 1.41-12.69, P = 0.01) and for DFS kurtosis (medium texture, HR 3.97, 95% CI: 1.44-10.94, P = 0.007) and CRM involvement on MRI (HR 3.36, 95% CI: 1.21-9.32, P = 0.02) were the independent post-treatment factors. Only TA independently predicted RFS on pre- or post-treatment analyses.
  
  
  CONCLUSIONS
  MR based TA of rectal cancers can predict outcome before undergoing surgery and could potentially select patients for individualized therapy.
authors.affiliation: Colchester University Hospital, Colchester, UK.
authors.forename: O
authors.initials: O
authors.lastname: Jalil
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Afaq
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: B
authors.initials: B
authors.lastname: Ganeshan
authors.affiliation: London North-West NHS Trust, London, UK.
authors.forename: U B
authors.initials: UB
authors.lastname: Patel
authors.affiliation: Colchester University Hospital, Colchester, UK.
authors.forename: D
authors.initials: D
authors.lastname: Boone
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Endozo
authors.affiliation: Institute of Nuclear Medicine, University College London, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Groves
authors.affiliation: Colchester University Hospital, Colchester, UK.
authors.forename: B
authors.initials: B
authors.lastname: Sizer
authors.affiliation: Colchester University Hospital, Colchester, UK.
authors.forename: T
authors.initials: T
authors.lastname: Arulampalam
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D059248:Chemoradiotherapy / Q000379:methods / Q000401:mortality*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000628:therapy; D012007:Rectum / Q000473:pathology*; D012044:Regression Analysis; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor
keywords: MRI; Textural analysis; imaging biomarker; neoadjuvant chemoradiotherapy; rectal cancer