title: Hyperpolarized (3)He magnetic resonance imaging: comparison with four-dimensional x-ray computed tomography imaging in lung cancer.
abstract: OBJECTIVE
  Pulmonary functional imaging using four-dimensional x-ray computed tomographic (4DCT) imaging and hyperpolarized (3)He magnetic resonance imaging (MRI) provides regional lung function estimates in patients with lung cancer in whom pulmonary function measurements are typically dominated by tumor burden. The aim of this study was to evaluate the quantitative spatial relationship between 4DCT and hyperpolarized (3)He MRI ventilation maps.
  
  
  METHODS
  Eleven patients with lung cancer provided written informed consent to 4DCT imaging and MRI performed within 11 ± 14 days. Hyperpolarized (3)He MRI was acquired in breath-hold after inhalation from functional residual capacity of 1 L hyperpolarized (3)He, whereas 4DCT imaging was acquired over a single tidal breath of room air. For hyperpolarized (3)He MRI, the percentage ventilated volume was generated using semiautomated segmentation; for 4DCT imaging, pulmonary function maps were generated using the correspondence between identical tissue elements at inspiratory and expiratory phases to generate percentage ventilated volume.
  
  
  RESULTS
  After accounting for differences in image acquisition lung volumes ((3)He MRI: 1.9 ± 0.5 L ipsilateral, 2.3 ± 0.7 L contralateral; 4DCT imaging: 1.2 ± 0.3 L ipsilateral, 1.3 ± 0.4 L contralateral), there was no significant difference in percentage ventilated volume between hyperpolarized (3)He MRI (72 ± 11% ipsilateral, 79 ± 12% contralateral) and 4DCT imaging (74 ± 3% ipsilateral, 75 ± 4% contralateral). Spatial correspondence between 4DCT and (3)He MRI ventilation was evaluated using the Dice similarity coefficient index (ipsilateral, 86 ± 12%; contralateral, 88 ± 12%).
  
  
  CONCLUSIONS
  Despite rather large differences in image acquisition breathing maneuvers, good spatial and significant quantitative agreement was observed for ventilation maps on hyperpolarized (3)He MRI and 4DCT imaging, suggesting that pulmonary regions with good lung function are similar between modalities in this small group of patients with lung cancer.
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, London, ON N6A 5K8, Canada.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Mathew
authors.forename: Andrew
authors.initials: A
authors.lastname: Wheatley
authors.forename: Richard
authors.initials: R
authors.lastname: Castillo
authors.forename: Edward
authors.initials: E
authors.lastname: Castillo
authors.forename: George
authors.initials: G
authors.lastname: Rodrigues
authors.forename: Thomas
authors.initials: T
authors.lastname: Guerrero
authors.forename: Grace
authors.initials: G
authors.lastname: Parraga
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D005541:Forced Expiratory Volume; D056973:Four-Dimensional Computed Tomography; D006371:Helium; D006801:Humans; D007554:Isotopes; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008176:Lung Volume Measurements; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012123:Pulmonary Ventilation
chemical_list: D007554:Isotopes; D006371:Helium