Clinical studies of chronic pulmonary emphysema on computed tomography

In order to assess the usefulness of CT for the evaluation of chronic pulmonary emphysema (CPE), three studies were made as follows. Correlation between CT findings and pulmonary function tests (PFT's) was studied by a scoring method in 41 patients with clinically diagnosed CPE. CT visual score was best correlated with DLCO (r=-0.68) and %DLCO (r=-0.74). The coexistence of bronchial lesion was considered to be responsible for the discrepancy between CT findings and PFT's in patients with low visual score. Alteration ratios of lung field CT numbers in different respiratory phases were studied in 30 cases with CPE, 15 cases with s/o CPE, 7 cases with bronchial asthma and 20 cases with normal lung. Among three parameters we employed, %(I-E)/W, i.e., the alteration ratio of whole lung fields CT numbers between fully inspired and entirely expired state, was proved to be best parameter to separate the disease groups from each other. %(I-E)/W had good correlation with FEV1.0% (r=0.79), V25/H (r=0.80) and RV/TLC (r=-0.75), and this parameter was considered to be useful for the diagnosis of CPE. CT-functional images (CT-FI's) were created from Xe-dynamic CT data of 10 patients with CPE and 6 volunteers with normal lung. For each case, the distribution of ventilation dynamics was compared between outer and inner zone of lung fields. In CT-FI's of normal lungs, the values of washin and washout parameter of outer zone were larger than those of inner zone. In CT-FL's of CPE, the values of washin parameter of inner zone were larger than those of outer zone and the values of washout parameter of outer zone were larger than those of inner zone. CT-FI proved to be helpful in evaluating the distribution of ventilation dynamics in axial planes of the lung with CPE. (author) 83 refs