2.2. CT and PFTs
Before CT scanning, all patients received instructed training to achieve
full-inspiratory and end expiratory breath hold. CT scans during full
inspiration and end expiration were obtained craniocaudally in the
supine position throughout the entire thorax without intravenous
contrast material. All CT examinations were performed using a helical CT
scanner (Somatom Force, Siemens Medical Systems, Erlangen, Germany)
using a 250–350 mm field of view, a 512×512 reconstruction matrix,
80~100 kVp, effective mAs (CARE Dose 4D), and a tube
rotation time of 0.25 ms. For lung parenchymal analysis, images were
reconstructed using the following parameters: 1 mm thickness, no
interval, and Br36 kernel. CT attenuation measurements were taken using
the CT Pulmo 3D application in a 3D solution program (Syngovia;
Siemens). The application calculated the attenuation coefficient for
each voxel in the lung and a frequency distribution of voxels with
specific attenuation numbers.
All PFTs were performed with a Vmax instrument (Sensor Medics, VIASYS
Healthcare, Yorba Linda, CA) according to guidelines from the American
Thoracic Society and European Respiratory Society.