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Automatic Tracking of the Respiratory Motion of Lung Parenchyma on Dynamic Magnetic Resonance Imaging: Comparison With Pulmonary Function Tests in Patients With Chronic Obstructive Pulmonary Disease

Purpose This study evaluated the respiratory motion of the lung parenchyma using dynamic magnetic resonance imaging and clarified differences between healthy individuals and patients with chronic obstructive pulmonary disease (COPD). Materials and Methods The study comprised 6 healthy volunteers and 42 patients diagnosed with smoking-related COPD. We captured 80 sequential frames from the mid-sagittal portion of the right lung while repeating forced deep breathing using a balanced fast-field echo sequence (repetition time, 2.2 ms; echo time, 1.1 ms; slice thickness, 10 mm; field of view, 450 mm; matrix size, 128×256; and acquisition time, 0.28 s/frame). We traced 15 points on pulmonary vessels using a computer-aided system and measured the maximal motion distance of each tracked point. Movement of these points was then compared with spirometric data using the Pearson correlation coefficient. Results Patients with COPD showed reduced respiratory motion compared with healthy volunteers. Respiratory motion and spirometric data such as forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity showed highly significant positive correlations (correlation between normalized motion distance for the whole lung and FEV1, r=0.75; P<0.01). Conclusions The respiratory motion of the pulmonary vessels reflects expansion and deflation of the lung parenchyma, and such motion is restricted in patients with COPD due to airflow limitation.