Takayuki Kanai1, Noriyuki Kadoya2, Kengo Ito1, Kazuma Kishi3, Suguru Dobashi4, Takaya Yamamoto1, Rei Umezawa1, Haruo Matsushita1, Ken Takeda4, Keiichi Jingu1. 1. Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. 2. Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan. Electronic address: kadoya.n@rad.med.tohoku.ac.jp. 3. Radiation Technology, Tohoku University Hospital, Sendai, Japan. 4. Department of Radiological Technology, School of Health Sciences, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract
PURPOSE: 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. METHODS AND MATERIALS: 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. RESULTS: 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. CONCLUSIONS: 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.
PURPOSE: 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. METHODS AND MATERIALS: Eleven lung cancerpatients 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. RESULTS: 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. CONCLUSIONS: 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: Tokihiro Yamamoto; Sven Kabus; Matthieu Bal; Karl Bzdusek; Paul J Keall; Cari Wright; Stanley H Benedict; Megan E Daly Journal: Int J Radiat Oncol Biol Phys Date: 2018-05-04 Impact factor: 7.038