title: Comparison of the quantitative CT imaging biomarkers of idiopathic pulmonary fibrosis at baseline and early change with an interval of 7 months.
abstract: OBJECTIVE
  Median survival of patients with idiopathic pulmonary fibrosis (IPF) is 2-5 years. Sensitive imaging metrics can play a role in detecting early changes in therapeutic development. The aim of the present study was to compare known computed tomography (CT) histogram kurtosis and a classifier-based quantitative score to assess baseline severity and change over time in patients with IPF.
  
  
  METHODS
  A total of 57 patients with at least baseline and paired follow-up scans were selected from an imaging database of standardized CT scans obtained from patients with IPF. CT histogram measurement of kurtosis and quantitative lung fibrosis (QLF) and quantitative interstitial lung disease (QILD) scores from a classification algorithm were calculated. Spearman rank correlations were used to assess associations between baseline severity and changes for all CT-derived measures compared to forced vital capacity (FVC) and carbon monoxide diffusion capacity (DLCO) (percent predicted).
  
  
  RESULTS
  At baseline, mean (±SD) of kurtosis was 2.43 (±1.83). Mean (±SD) values of QLF and QILD scores were 20.7% (±13.4) and 43.3% (±20.0), respectively. All baseline histogram indices and QLF and QILD scores were correlated well with baseline FVC and DLCO. When assessing associations with changes in FVC and DLCO over time, only QLF score was statistically significant (ρ = -0.57; P < .0001 for FVC and ρ = -0.34; P = .025 for DLCO), whereas kurtosis was not.
  
  
  CONCLUSIONS
  Classifier-model-derived scores (QLF and QILD), based on a set of texture features, are associated with baseline disease extent and are also a sensitive measure of change over time. A QLF score can be used for measuring the extent of disease severity and longitudinal changes.
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California; Department of Biostatistics, Fielding School of Public Health, UCLA, Los Angeles, CA 90024. Electronic address: gracekim@mednet.ucla.edu.
authors.forename: Hyun J
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Brown
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Daniel
authors.initials: D
authors.lastname: Chong
authors.affiliation: Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California; Department of Biostatistics, Fielding School of Public Health, UCLA, Los Angeles, CA 90024; Department of Pathology, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: David W
authors.initials: DW
authors.lastname: Gjertson
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Peiyun
authors.initials: P
authors.lastname: Lu
authors.affiliation: Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Hak J
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Heidi
authors.initials: H
authors.lastname: Coy
authors.affiliation: Center for Computer Vision and Imaging Biomarkers; Department of Radiological Science, David Geffen School of Medicine, UCLA, Los Angeles, California.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Goldin
mesh_terms: D018450:Disease Progression; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000000981:diagnostic imaging*; D008137:Longitudinal Studies; D008297:Male; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CAD; ILD; IPF; Texture; imaging biomarkers; quantitative lung fibrosis