title: Comparison of 4-dimensional computed tomography ventilation with nuclear medicine ventilation-perfusion imaging: a clinical validation study.
abstract: OBJECTIVE
  Four-dimensional computed tomography (4DCT) ventilation imaging provides lung function information for lung cancer patients undergoing radiation therapy. Before 4DCT-ventilation can be implemented clinically it needs to be validated against an established imaging modality. The purpose of this work was to compare 4DCT-ventilation to nuclear medicine ventilation, using clinically relevant global metrics and radiologist observations.
  
  
  METHODS
  Fifteen lung cancer patients with 16 sets of 4DCT and nuclear medicine ventilation-perfusion (VQ) images were used for the study. The VQ-ventilation images were acquired in planar mode using Tc-99m-labeled diethylenetriamine-pentaacetic acid aerosol inhalation. 4DCT data, spatial registration, and a density-change-based model were used to compute a 4DCT-based ventilation map for each patient. The percent ventilation was calculated in each lung and each lung third for both the 4DCT and VQ-ventilation scans. A nuclear medicine radiologist assessed the VQ and 4DCT scans for the presence of ventilation defects. The VQ and 4DCT-based images were compared using regional percent ventilation and radiologist clinical observations.
  
  
  RESULTS
  Individual patient examples demonstrate good qualitative agreement between the 4DCT and VQ-ventilation scans. The correlation coefficients were 0.68 and 0.45, using the percent ventilation in each individual lung and lung third, respectively. Using radiologist-noted presence of ventilation defects and receiver operating characteristic analysis, the sensitivity, specificity, and accuracy of the 4DCT-ventilation were 90%, 64%, and 81%, respectively.
  
  
  CONCLUSIONS
  The current work compared 4DCT with VQ-based ventilation using clinically relevant global metrics and radiologist observations. We found good agreement between the radiologist's assessment of the 4DCT and VQ-ventilation images as well as the percent ventilation in each lung. The agreement lessened when the data were analyzed on a regional level. Our study presents an important step for the integration of 4DCT-ventilation into thoracic clinical practice.
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado. Electronic address: yevgeniy.vinogradskiy@ucdenver.edu.
authors.forename: Yevgeniy
authors.initials: Y
authors.lastname: Vinogradskiy
authors.affiliation: Department of Radiology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Koo
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Richard
authors.initials: R
authors.lastname: Castillo
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Computational and Applied Mathematics, Rice University, Houston, Texas.
authors.forename: Edward
authors.initials: E
authors.lastname: Castillo
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; Department of Computational and Applied Mathematics, Rice University, Houston, Texas.
authors.forename: Thomas
authors.initials: T
authors.lastname: Guerrero
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Laurie E
authors.initials: LE
authors.lastname: Gaspar
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Moyed
authors.initials: M
authors.lastname: Miften
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Kavanagh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000532:radiotherapy; D008297:Male; D008875:Middle Aged; D009683:Nuclear Medicine; D015588:Observer Variation; D055420:Perfusion Imaging / Q000379:methods*; D012123:Pulmonary Ventilation / Q000502:physiology*; D011871:Radiology; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate; D014692:Ventilation-Perfusion Ratio / Q000502:physiology
chemical_list: D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate
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