title: Prognostic value and reproducibility of pretreatment CT texture features in stage III non-small cell lung cancer.
abstract: OBJECTIVE
  To determine whether pretreatment CT texture features can improve patient risk stratification beyond conventional prognostic factors (CPFs) in stage III non-small cell lung cancer (NSCLC).
  
  
  METHODS
  We retrospectively reviewed 91 cases with stage III NSCLC treated with definitive chemoradiation therapy. All patients underwent pretreatment diagnostic contrast enhanced computed tomography (CE-CT) followed by 4-dimensional CT (4D-CT) for treatment simulation. We used the average-CT and expiratory (T50-CT) images from the 4D-CT along with the CE-CT for texture extraction. Histogram, gradient, co-occurrence, gray tone difference, and filtration-based techniques were used for texture feature extraction. Penalized Cox regression implementing cross-validation was used for covariate selection and modeling. Models incorporating texture features from the 33 image types and CPFs were compared to those with models incorporating CPFs alone for overall survival (OS), local-regional control (LRC), and freedom from distant metastases (FFDM). Predictive Kaplan-Meier curves were generated using leave-one-out cross-validation. Patients were stratified based on whether their predicted outcome was above or below the median. Reproducibility of texture features was evaluated using test-retest scans from independent patients and quantified using concordance correlation coefficients (CCC). We compared models incorporating the reproducibility seen on test-retest scans to our original models and determined the classification reproducibility.
  
  
  RESULTS
  Models incorporating both texture features and CPFs demonstrated a significant improvement in risk stratification compared to models using CPFs alone for OS (P=.046), LRC (P=.01), and FFDM (P=.005). The average CCCs were 0.89, 0.91, and 0.67 for texture features extracted from the average-CT, T50-CT, and CE-CT, respectively. Incorporating reproducibility within our models yielded 80.4% (±3.7% SD), 78.3% (±4.0% SD), and 78.8% (±3.9% SD) classification reproducibility in terms of OS, LRC, and FFDM, respectively.
  
  
  CONCLUSIONS
  Pretreatment tumor texture may provide prognostic information beyond that obtained from CPFs. Models incorporating feature reproducibility achieved classification rates of ∼80%. External validation would be required to establish texture as a prognostic factor.
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas; Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: David V
authors.initials: DV
authors.lastname: Fried
authors.affiliation: Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Tucker
authors.affiliation: Division of Quantitative Sciences, Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Shouhao
authors.initials: S
authors.lastname: Zhou
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Liao
authors.affiliation: Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Osama
authors.initials: O
authors.lastname: Mawlawi
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas; Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Ibbott
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas; Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas. Electronic address: LECourt@mdanderson.org.
authors.forename: Laurence E
authors.initials: LE
authors.lastname: Court
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy; D059248:Chemoradiotherapy; D003287:Contrast Media; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D060828:Induction Chemotherapy / Q000379:methods; D017567:Karnofsky Performance Status; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009068:Movement; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D011880:Radiotherapy Planning, Computer-Assisted; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media