Some of these 133 patients were preliminarily assessed in our previous research for a different purpose.13 After the CT scans of all subjects were reviewed by a board-certified radiologist of the Japan Radiological Society (TY, with
13 years’ experience in thoracic radiology), 22 patients with visible pulmonary emphysema on chest CT were selected for this quantitative investigation. We did not include patients with sub-pleural bullae who did not have pulmonary emphysema. The enrolled patients included four women and 18 men. Their mean age was 67±11 years and mean body weight was 60.6±12.3 kg.