title: Second-order Texture Measurements of (3)He Ventilation MRI: Proof-of-concept Evaluation of Asthma Bronchodilator Response.
abstract: OBJECTIVE
  (3)He magnetic resonance imaging (MRI) can be used to quantify functional responses to asthma therapy and provocation. Ventilation imaging offers quantitative information beyond ventilation defects that have not yet been exploited. Therefore, our objective was to evaluate hyperpolarized (3)He MRI ventilation defect percent (VDP) and compare this and pulmonary function measurements to ventilation image texture features and their changes post-bronchodilator administration in patients with asthma.
  
  
  METHODS
  Volunteers with a diagnosis of asthma provided written informed consent to an ethics board-approved protocol and underwent pulmonary function tests and MRI before and after salbutamol inhalation. MR images were analyzed using VDP, and their texture was evaluated via gray-level run-length matrices. These texture classifiers were compared to VDP in responders to bronchodilation based on VDP (VDP responders) and forced expiratory volume in 1 s (FEV1) (FEV1 responders).
  
  
  RESULTS
  In total, 47 patients with asthma (18 males 39 ± 13 years, FEV1 = 79 ± 21%) reported significantly improved FEV1, FEV1/forced vital capacity (FVC), residual volume (RV)/total lung capacity (TLC) (all P = .0001) and VDP (P = .01) post-salbutamol. Post-salbutamol, VDP responders and nonresponders to salbutamol were significantly different for coarse-texture features including long-run emphasis (LRE) and long-run, low gray-level emphasis (LRLGE, both P < .05) and for FEV1 responders to salbutamol, there was significantly different long-run, high gray-level emphasis (LRHGE, P = .04). There were significant relationships for VDP with LRE (R = .50, P = .0003), LRLGE (R = .34, P = .02), and LRHGE (R = .56, P = .0001). Receiver operating characteristic curves showed VDP with the strongest performance (AUC = .92), followed by coarse-texture classifier LRHGE (AUC = .83), FEV1 (AUC = .80), LRE (AUC = .66), FVC (AUC = .58), and LRLGE (AUC = .42).
  
  
  CONCLUSIONS
  In patients with asthma, differences in ventilation patchiness post-salbutamol can be quantified using coarse-texture classifiers that are significantly different in bronchodilator responders.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada.
authors.forename: Nanxi
authors.initials: N
authors.lastname: Zha
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada.
authors.forename: Damien
authors.initials: D
authors.lastname: Pike
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Svenningsen
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada.
authors.forename: Dante P I
authors.initials: DP
authors.lastname: Capaldi
authors.affiliation: Division of Respirology, Department of Medicine, The University of Western Ontario, London, Canada.
authors.forename: David G
authors.initials: DG
authors.lastname: McCormack
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 1151 Richmond Street North, London, ON N6A 5B7, Canada; Department of Medical Biophysics, The University of Western Ontario, London, Canada. Electronic address: gparraga@robarts.ca.
authors.forename: Grace
authors.initials: G
authors.lastname: Parraga
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage*; D019540:Area Under Curve; D001249:Asthma / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006371:Helium; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007554:Isotopes; D008168:Lung / Q000000981:diagnostic imaging / Q000187:drug effects; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008450:Maximal Midexpiratory Flow Rate / Q000187:drug effects; D008875:Middle Aged; D012372:ROC Curve; D012115:Residual Volume / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D012129:Respiratory Function Tests / Q000379:methods; D059629:Signal-To-Noise Ratio; D013147:Spirometry / Q000379:methods; D014109:Total Lung Capacity / Q000187:drug effects; D014797:Vital Capacity / Q000187:drug effects
chemical_list: D001993:Bronchodilator Agents; D007554:Isotopes; D006371:Helium; D000420:Albuterol
keywords: (3)He MRI; Texture analysis; asthma; bronchodilator response