Abstract
When defining a complexity as the number of dominant movement patterns of the lung internal structures movement, a variety of different situations are found in COPD (chronic obstructive pulmonary disease) patients. Furthermore, there is no clear correspondence among the complexity and the disease severity. On the other hand, the LAA% (ratio of low attenuation area to total lung area) is reported to correlate with respiratory function parameters, such as FEV1/FVC (ratio of forced expiratory volume in 1 second to forced vital capacity) to some degree. This study attempts to explain this diversity by combining dynamic parameters derived from the internal lung structures movement with the LAA%. Time sequential MR sagittal images with balanced FFE sequences are taken at the mid portion of the right lung during deep breathing for 5 healthy volunteers and 24 patients with COPD (4 in Grade I; 10 in Grade II, 8 in Grade III and 2 in Grade IV).CT images were also taken during breath holding. The movement of the lung is extracted from MR images by tracking sample points on arterial and venous blood vessels up to subsegmental branches. Main motion patterns are obtained for each lobe as well the whole lung. Dynamic parameters such as variance of displacement and swept area are obtained for each lobe from the sample points movement. LAA% is obtained from CT images. The correlations between FEV1/FVC and parameters derived from the lung motion as well as LAA% are performed using multi-regression analysis. The conclusions are that LAA% contribution to FEV1/FVC is practically equal to the lung movement dispersions and that a high correlation is obtained from the combination of LAA% and dynamic parameters.
