Original InvestigationAirflow Limitation in Chronic Obstructive Pulmonary Disease: Ratio and Difference of Percentage of Low-attenuation Lung Regions in Paired Inspiratory/Expiratory Computed Tomography
Section snippets
Materials and methods
The institutional review board of our hospital approved this study. Written informed consent was obtained from all patients for the use of their data.
Results
The pulmonary function test results and CT measurements are summarized in Table 1, Table 2. The correlation coefficients between LAA% and FEV1 in inspiratory and expiratory CT are shown in Table 3. The correlation coefficients of LAA% in inspiratory CT ranged from −0.517 to −0.193, and the corresponding P values ranged from .00344 to .307. In expiratory CT, the correlation coefficients of LAA% ranged from −0.644 to −0.370, and the corresponding P values ranged from 1.24 × 10−4 to .0443. In
Discussion
In the present study, we observed that the LAA% E/I ratio and E/I difference significantly correlated with airflow limitation measured by the pulmonary function test and that the LAA% E/I difference showed stronger correlation with the pulmonary function test results than the other types of CT measurements.
Airflow limitation in COPD is caused by lung parenchymal destruction and small airway disease. According to previous reports, LAA% in inspiratory CT reflected airflow limitation in the
Conclusion
The LAA% E/I ratio and E/I difference were significantly correlated with airflow limitation in patients with COPD. The LAA% thresholds in paired inspiratory/expiratory CT caused a large variability in the correlation with airflow limitation. Although it is necessary to confirm these results in a larger patient cohort, the LAA% E/I ratio and E/I difference are expected to be useful for assessing airflow limitation in COPD.
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