title: Evaluation of four-dimensional computed tomography (4D-CT)-based pulmonary ventilation: The high correlation between 4D-CT ventilation and (81m)Kr-planar images was found.
abstract: To evaluate four-dimensional computed tomography (4D-CT)-derived pulmonary ventilation by comparing with (81m)Kr-gas ventilation (VRI). We also proposed two methods to improve the functional accuracy of 4D-CT ventilation images and evaluated these methods.
  
  
  
  Eleven lung cancer patients with 4D-CT and VRI were analyzed. Hounsfield unit-based (VHU) and a Jacobian-based (VJac) 4D-CT ventilation images were calculated. They were evaluated by voxel-by-voxel spearman's rank correlation coefficient (r) between 4D-CT ventilation and VRI images. After applying an averaging ventilation method and a slope calculating method, correlations were also calculated.
  
  
  
  4D-CT ventilation showed the high correlation to VRI (r=0.875 with VHU). An averaging method brought significantly higher (p=0.012) correlations to nuclear medicine images with VHU. The improvement was not significant (p=0.619) with VJac. Slope calculating method improved the correlation with VHU and slightly worsened the correlation with VJac.
  
  
  
  The averaging method we proposed might be useful to improve 4D-CT ventilation images. We found good agreement between 4D-CT ventilation and nuclear medicine ventilation, indicating the high physiologic accuracy of 4D-CT ventilation.
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kanai
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. Electronic address: kadoya.n@rad.med.tohoku.ac.jp.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kadoya
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.affiliation: Radiation Technology, Tohoku University Hospital, Sendai, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Kishi
authors.affiliation: Department of Radiological Technology, School of Health Sciences, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Dobashi
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Takaya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Umezawa
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Department of Radiological Technology, School of Health Sciences, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Jingu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D056973:Four-Dimensional Computed Tomography / Q000379:methods*; D006801:Humans; D007727:Krypton Radioisotopes; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D012123:Pulmonary Ventilation
chemical_list: D007727:Krypton Radioisotopes
keywords: (81m)Kr-gas ventilation; 4D-CT ventilation; Functional imaging