QUANTITATIVE ASSESSMENT OF PULMONARY EMPHYSEMA, USING DENSITY MASK PROGRAM, IN CORRELATION TO PULMONARY FUNCTIONS
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The purpose of this study is to assess the value of high resolution computed tomography (HRCT) in quantitative assessment of pulmonary emphysema in correlation with pulmonary functions. Our study included 50 patients with emphysema diagnosed using clinical, functional and radiological examination, and "10" healthy male volunteers as a control group. Patients subjected to both pulmonary function testing and HRCT with quantification of emphysema using density mask program to calculate Low Attenuation Areas (LAA)% in three zones of lungs (upper, middle and lower). We used a CT program "density mask" outlining areas with attenuation values less than -960 HI), to indicate areas of emphysema on a chest CT and to provide an overall percentage of lung involvement by emphysema. Data collected subjected to statistical analysis revealing that, emphysema is associated with increased total lung capacity and residual volume both absolute and percent of predicted. Emphysema is associated with decreased expiratory flow rates and diffusing capacity for carbon monoxide. There is highly significant positive correlation between LAA% and expiratory flow rates and diffusing capacity of carbon monoxide. There is highly significant negative correlation between LAA% and expiratory flow rates and diffusing capacity of carbon monoxide. LAA% in upper and middle lung zones are more correlated with DLCO% and DLCONA than the lower lung zone. Small airway function PEP 25-75% is mostly correlated with LAA% in the middle and lower lung zones than in upper lung zone. Conclusion: Determination of the percentage of lung with areas of low attenuation by HRCT provides a useful method for quantitating emphysema in life and correlates significantly with pulmonary function tests. The capability of HRCT to quantify pulmonary emphysema accurately, based on subjective visual grading and on objective measurements of attenuation values, contributing unique software, which provided numerical data, and comparing CT data with pulmonary function tests.