Quantifying the Changes Observed Throughout Respiration Using Dynamic Chest Radiography

Abstract

RATIONALE Dynamic Chest radiography (DCR) involves taking sequential x-ray images throughout the patients breathing cycle. This allows for quantifiable measurements of diaphragmatic movement, cardiac motion, pulmonary ventilation and circulation. Recent studies have begun to correlate DCR obtained values with conventional measures of pulmonary physiology, such as spirometry. This technique therefore has the potential to become a rapid means of assessing both pulmonary anatomy and physiology. Two key DCR measurements, 'maximal distance from lung apex to the diaphragm' and 'total lung area' can used to calculate the change in area occurring between inspiration and expiration, or 'DCR equivalent Forced Vital Capacity' (DCR FVC). The aim of this study is to investigate the use of DCR FVC and assess the level of agreement between the two key measurements. METHODS The DCR images for 50 individual patients were obtained. The values for 'maximal distance from lung apex to the diaphragm' and 'total lung area' were calculated for both lungs during maximal inspiration and expiration. The difference between inspiration and expiration was used to generate DCR FVC and data was collated in a spreadsheet. Summary statistics were calculated, and Pearson's correlation coefficients were used to compare 'maximal distance from lung apex to the diaphragm' and 'total lung area' values. RESULTS Values were obtained for all 50 patients. The