title: Clinical validation of 4-dimensional computed tomography ventilation with pulmonary function test data.
abstract: OBJECTIVE
  A new form of functional imaging has been proposed in the form of 4-dimensional computed tomography (4DCT) ventilation. Because 4DCTs are acquired as part of routine care for lung cancer patients, calculating ventilation maps from 4DCTs provides spatial lung function information without added dosimetric or monetary cost to the patient. Before 4DCT-ventilation is implemented it needs to be clinically validated. Pulmonary function tests (PFTs) provide a clinically established way of evaluating lung function. The purpose of our work was to perform a clinical validation by comparing 4DCT-ventilation metrics with PFT data.
  
  
  METHODS
  Ninety-eight lung cancer patients with pretreatment 4DCT and PFT data were included in the study. Pulmonary function test metrics used to diagnose obstructive lung disease were recorded: forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity. Four-dimensional CT data sets and spatial registration were used to compute 4DCT-ventilation images using a density change-based and a Jacobian-based model. The ventilation maps were reduced to single metrics intended to reflect the degree of ventilation obstruction. Specifically, we computed the coefficient of variation (SD/mean), ventilation V20 (volume of lung ≤20% ventilation), and correlated the ventilation metrics with PFT data. Regression analysis was used to determine whether 4DCT ventilation data could predict for normal versus abnormal lung function using PFT thresholds.
  
  
  RESULTS
  Correlation coefficients comparing 4DCT-ventilation with PFT data ranged from 0.63 to 0.72, with the best agreement between FEV1 and coefficient of variation. Four-dimensional CT ventilation metrics were able to significantly delineate between clinically normal versus abnormal PFT results.
  
  
  CONCLUSIONS
  Validation of 4DCT ventilation with clinically relevant metrics is essential. We demonstrate good global agreement between PFTs and 4DCT-ventilation, indicating that 4DCT-ventilation provides a reliable assessment of lung function. Four-dimensional CT ventilation enables exciting opportunities to assess lung function and create functional avoidance radiation therapy plans. The present work provides supporting evidence for the integration of 4DCT-ventilation into clinical trials.
authors: University of Colorado School of Medicine, Aurora, Colorado.
authors: Douglas
authors: D
authors: Brennan
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Leah
authors: L
authors: Schubert
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Quentin
authors: Q
authors: Diot
authors: Department of Radiation Oncology, The University of Texas Medical Branch, Galveston, Texas.
authors: Richard
authors: R
authors: Castillo
authors: Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan.
authors: Edward
authors: E
authors: Castillo
authors: Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan.
authors: Thomas
authors: T
authors: Guerrero
authors: Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, Houston, Texas.
authors: Mary K
authors: MK
authors: Martel
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Derek
authors: D
authors: Linderman
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Laurie E
authors: LE
authors: Gaspar
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Moyed
authors: M
authors: Miften
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors: Brian D
authors: BD
authors: Kavanagh
authors: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado. Electronic address: yevgeniy.vinogradskiy@ucdenver.edu.
authors: Yevgeniy
authors: Y
authors: Vinogradskiy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005541:Forced Expiratory Volume; D056973:Four-Dimensional Computed Tomography; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D012044:Regression Analysis; D012129:Respiratory Function Tests; D014797:Vital Capacity